Lipid peroxidation is a chemical process involving the oxidative degradation of lipids, particularly polyunsaturated fatty acids (PUFAs) such as arachidonic acid. It´s initiated when free radicals, especially reactive oxidative species, "steal" electrons from lipids, resulting in the formation of lipid radicals and cell damage.

This process occurs through three stages: 

▌Initiation: A free radical (often hydroxyl radical) abstracts a hydrogen atom from a PUFA, creating a lipid radical. 
▌Propagation: The lipid radical reacts with molecular oxygen to form a lipid peroxyl radical, which can then abstract hydrogen  from another lipid, continuing a chain reaction and forming lipid hydroperoxides.
▌Termination: The chain ends when two radicals combine or antioxidants (like vitamin E) neutralise them, forming non-radical products.  [1][2] 

Uncontrolled  lipid peroxidation leads to membrane damage, cell dysfunction and death. While it occurs naturally during aging, external factors such as UV radiation, pollution, and cigarette smoke accelerate lipid peroxidation by generating reactive oxygen species (ROS). These ROS interact with PUFAs in cell membranes, initiating a cascading chain reaction that produces toxic aldehydes like malondialdehyde (MDA) and 4-hydroxy-2-nonenal (4-HNE), which contribute to oxidative stress, cellular damage, and programmed cell death mechanisms like apoptosis and ferroptosis [1][2][3]. 

Sebum is primarily composed of saturated fatty acids (e.g., palmitic acid at ~31%) and monounsaturated fatty acids (e.g., sapienic acid at ~21%), but it also contains smaller quantities of PUFAs such as linoleic acid [4][5]. Despite their lower abundance, sebum PUFAs are highly susceptible to peroxidation due to their double-bond structure [1][3].  For example, in acne patients, reduced sebum PUFA levels correlate with inflammatory states, while increased saturated fatty acids exacerbate pro-inflammatory cytokine production [4]. This highlights the dual role of sebum lipids in maintaining skin barrier function and contributing to oxidative damage when peroxidation occurs [4][5].
​
Lipid peroxidation plays a role in various skin conditions, including acne and signs of photoaging [6][7], rosacea, psoriasis and eczema.

OILY SKIN AND LIPID PEROXIDATION

Oily skin is more susceptibility to lipid peroxidation due to increased sebum production and lipid accumulation at the skin surface [8]. The higher concentrations of sebum provides more substrate for oxidation, increasing the risk of barrier damage (membrane disruption), inflammation (triggering cytokine release), breakouts and cell death.

1. Altered sebum composition: UV radiation and pollution induce non-enzymatic oxidation of sebum lipids, generating comedogenic oxidation products that that spark acne-related inflammation [8][9]. The oxidation process particularly affects squalene and unsaturated fatty acids [10].
2. Squalene oxidation: As the most oxidation-prone sebum component, squalene generates pro-inflammatory peroxidation byproducts (e.g., squalene peroxides) when exposed to UV radiation [9][11]. These oxidized derivatives activate aryl hydrocarbon receptor pathways and promote inflammatory responses in keratinocytes [11]. 
3. Barrier integrity disruption: Lipid peroxidation products alter stratum corneum lipid organization, increasing trans-epidermal water loss and permeability. Reduced ceramides (especially Cer[NH] and Cer[AH]) worsen this barrier damage. [9].
4. Sebum viscosity changes: Oxidative modification increases sebum viscosity through formation of lipid peroxides and cross-linked polymers [8]. This thickened sebum causes pore blockage (follicular hyperkeratosis) and comedo formation, creating oxygen-free conditions where acne bacteria thrive [8].

​​ 
While lipid peroxidation is a natural byproduct of UV exposure, it is harmful at elevated levels. 
▌UV-mediated oxidation: UVA (320-400 nm) primarily drives non-enzymatic lipid oxidation (free radical pathways and non-radical pathways:oxygen oxidation, ozone reactions), while UVB activates enzymatic pathways (phospholipases, lipoxygenases) for eicosanoid production [9]. Eicosanoids are bioactive signaling molecules derived from polyunsaturated fatty acids (PUFAs) like arachidonic acid (AA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) which regulate inflammation, immunity, and vascular function.
Visible Light (including Blue Light) also contributes to lipid peroxidation.
▌Antioxidant depletion – lowered capacity: Oily skin types often experience an imbalance in antioxidant defenses. Also acne-prone skin has lower vitamin E levels, weakening protection against oxidative damage including squalene peroxidation [8][12]. A hallmark of sebum in acne patients is the presence of lipoperoxides, mainly due to the peroxidation of squalene and a decrease in the level of the major sebum antioxidants [13].
▌Acne inflammation cycle: Excess sebum attracts immune cells (neutrophils) that release damaging reactive chemicals, worsening oxidative stress [8]. This stress triggers lipid peroxidation, where oxidized fats act as inflammatory signals, directly worsening acne. Studies show higher levels of these oxidized fats in acne patients, strongly linked to inflamed lesions [14][15].

FERROPTOSIS AND SKIN HEALTH
Ferroptosis is a type of cell death caused by toxic buildup of damaged fats in cell membranes and is triggered by iron-driven lipid peroxidation when cells can’t neutralize harmful lipid peroxides, mainly due to glutathione peroxidase 4 (GPX4) failure. 

This happens through two key mechanisms:

1. Iron’s role: Iron generates destructive free radicals via Fenton reactions and fuels enzymes like lipoxygenases that oxidize lipids [16][17].
2. GPX4 breakdown: Without enough glutathione (GSH), GPX4 can’t convert toxic lipid peroxides into safe alcohols, causing lethal membrane damage [18][19].

The outcome is that uncontrolled lipid peroxides rupture cell membranes, executing iron-dependent ferroptosis [16].
 
STRATEGIES MANAGING OILY SKIN 

Effective skincare strategies for managing oily and acne-prone skin focuses on at least three key objectives [13]:
▌Inhibit the excessive secretion of sebaceous glands / reduce skin surface lipids
▌Improve the quality of sebum
▌Reduce the occurrence of lipid peroxidation  

1. Antioxidant-rich skincare: Incorporating topical products containing antioxidants such as vitamins C and E, and Licochalcone A can help neutralize free radicals and prevent oxidative damage to lipids [6]. Licochalcone A has been shown to inhibit lipid peroxidation in keratinocytes (the main cell type in the epidermis) induced by UV radiation [20], and in human dermal fibroblasts exposed to hydrogen peroxide [21].   
2. Melatonin: The hormone melatonin, is widely present in various tissues including the skin and regulates circadian rhythms and promotes sleep. Melatonin can penetrate membranes and mitigate lipid peroxidation and protein oxidation, as well as oxidative damage to the mitochondria and DNA caused by UVR [22]. 
3. Daily cleansing and regular exfoliation: Gentle exfoliants such as salicylic acid (a beta hydroxy acid) or glycolic acid (an alpha hydroxy acid), combined with regular cleansing, effectively remove oxidized lipids, pollutants, and debris from the skin's surface. This reduces the risk of oxidative stess and helps prevent pore congestion and reduces acne risk [14]. However, overcleansing or excessive exfoliation should be avoided—not due to the debunked "rebound sebum production" myth, however because these practices can compromise the stratum corneum's barrier function, increasing transepidermal water loss (TEWL) and irritation potential.
4. Sun protection: Exposure to UV and Visible Light light generates reactive oxygen species (ROS) and on top initiate lipid peroxidation in sebum, leading to the formation of lipid hydroperoxides and other oxidized lipids that can disrupt skin barrier function and promote inflammation [10]. The daily use of broad-spectrum sunscreen protects against UV and VL-induced oxidative stress which contribute to lipid peroxidation [7]. Sunscreens containing antioxidants (like Licochalcone A) can provide additional protection. Sunscreen efficacy directly correlates with reduced UV-induced lipid peroxidation.
5. Healthy diet: Consuming a diet rich in omega-3 fatty acids, fruits, and vegetables can enhance the skin's antioxidant defenses and reduce inflammation associated with lipid peroxidation [6].
6. Avoiding environmental stressors: Reducing exposure to pollutants and smoking can minimize oxidative stress on the skin. ​

7. Sebum regulating topical ingredients: There are several evidence based skin care ingredients. I will highlight one called L-Carnitine. L-Carnitine is a skin’s own amino acid derivative is produced from the amino acids lysine and methionine. It supports sebum regulation through several mechanisms:             
​▌Increased β-oxidation (“fat burning”): L-carnitine significantly augments β-oxidation in human sebocytes, which is the process by which fatty acids are broken down [23]. This leads to a decrease in intracellular lipid content.
▌Sebum secretion reduction: Topical application of a 2% L-carnitine formulation for 3 weeks significantly decreased the sebum secretion [23].
▌Bio-availability: Topically applied L-carnitine is bioavailable and can reach the dermis, allowing it to interact with sebaceous glands [23].
New in vitro data shows 86% sebum reduction for even a low concentration of L-carnitine [24].

8. Mattifying oil absorption: Mattifying agents formulated for oily skin work by absorbing excess sebum and reducing shine through ingredients like clays, silica, and polymers (like starch). Overuse can lead to product buildup, potentially trapping impurities on the skin's surface.
9. Blotting papers are thin, absorbent sheets designed to absorb thus remove excess oil from the skin's surface, providing a temporary matte appearance [25].

Always consult a qualified healthcare professional to determine what the most suitable approach is for your skin health and beauty.
​
Take care
Anne-Marie
  
[1] Ayala et al. Oxid Med Cell Longev. 2014;360438.
[2] Endale et al. Front Cell Dev Biol. 2023;11:1226044. 
[3] Su et al. Oxid Med Cell Longev. 2019;5080843.
[4] Cao et al. Front Physiol. 2022;13:921866.
[5] Sinclair et al. Nat Commun. 2021;12:1592.
[6] Briganti & Picardo (2003) J Eur Acad Dermatol Venereol. 17(6):663-9
[7] Niki (2015) Free Radic Res. 49(7):827-34
[8] Wong A, et al. J Clin Dermatol Ther. 2016;3(1):020.
[9] Gruber F, et al. Front Endocrinol. 2020;11:607076. 
[10] Picardo et al. (2009) Dermatoendocrinol. 1(2):68-71  (was 5)
[11] Kostyuk V, et al. PLoS One. 2012;7(8):e44472. 
[12] Briganti & Picardo (2003) J Eur Acad Dermatol Venereol. 17(6):663-9
[13] Ottaviani et al. (2006) J Invest Dermatol. 126:2430-2437
[14] Bowe & Logan (2010) Lipids Health Dis. 9:141
[15] Yadav et al. (2019) Sci Rep. 9:4496
[16] Tang, D. et al. (2021) Cell Res 31, 107–125. 
[17] Veeckmans, G. et al. (2023) The FEBS Journal.
[18] Li, J. et al. (2020) Cell Death Dis. 11, 88.
[19] Feng et al. (2023) Mol. Biomed. 4, 33.
[20] Kim et al. (2005) J Invest Dermatol. 125(5):1009-16
[21] Huang et al. (2013) Mol Med Rep. 7(6):1977-82
[22] Bocheva et al. (2022) Int J Mol Sci. 23:1238
[23] Peirano et al. (2012) J Cosmet Dermatol. 11(1):30-36
[24] BDF data on file Dr. Dorothea Schweiger
[25] Wu et al. (2019) J Food Drug Anal. 27(2):610-61

Collagen banking is a proactive skincare strategy falling under the category prejuvenation aimed at preserving and stimulating collagen production to maintain youthful, firm and excellent skin quality over time. This approach can involve using various treatments, tweakments, products, supplements and lifestyle choices to boost collagen levels before significant signs of aging appear. The goal is to build a "reserve" or “bank” of collagen, ensuring skin remains resilient and less prone to wrinkles and sagging as natural collagen production declines and degradation increases with age. To start banking collagen as early as in your twenties makes sense, as the producing cell called the dermal fibroblast is still very healthy and active. Moreover as the loss is not yet so great (just a few percent loss), thus less invasive methods work well to maintain a youthful status quo. I´s never too late to start “banking” collagen, although when you are more mature, the word rejuvenation might be more suitable. 
 
There is no direct scientific evidence that collagen stimulation is more effective in your twenties than in your sixties.
However, starting collagen stimulation earlier may be beneficial:
▌Collagen production begins to decline around age 25-30, decreasing by about 1% per year.
▌By the 50s and beyond, the collagen loss is greater >30%, becomes more noticeable and it´s always harder to get back what you lost than to maintain what you have.
▌Peak collagen levels occur at twenty years of age, thus maintaining what you have the highest achievable level.
▌Starting collagen stimulation treatments earlier may help prevent further collagen loss and require less invasive and number of treatments.
 
WHAT IS COLLAGEN
Collagen is the most abundant protein in the human body, making up about one-third of all proteins. 
1. Location: Found in connective tissues, including skin, tendons, bones, and cartilage.
2. Function: Provides structural support, strength, and elasticity to tissues.
3. Production: Naturally produced by the body, but production decreases with age, starting around the mid-20s.
Collagen plays a crucial role in maintaining skin elasticity, joint health, and overall tissue integrity. As collagen production declines with age, so does the skin quality, leading to visible signs of aging like wrinkles, loss of elasticity and firmness, and sagging skin. Collagen is one of the key target components for noticeable and effective skin rejuvenation or regeneration. 

Collagen is primarily composed of three key amino acids: 
▌Glycine: is the most abundant, contributing significantly to collagen's structure and stability 
▌ Proline
▌ Hydroxyproline
Proline and hydroxyproline are crucial for forming the triple-helix structure of collagen, which provides strength and flexibility. Additionally, essential amino acids like lysine play a critical role in collagen synthesis by forming hydroxylysine, important for stabilizing collagen fibers. A balanced intake of these amino acids is vital for maintaining healthy collagen levels in the body.

COLLAGEN DECLINE
Collagen production begins to diminish naturally in our mid-20s, decreasing by about 1% per year [2]. This decline becomes more pronounced in the 40s and 50s, contributing to visible signs of aging such as wrinkles and sagging skin [2]. Factors influencing collagen loss include genetic predisposition (DNA), changes in epigenetic pattern (influenced by environment), hormonal changes (especially post-menopause), and fibroblast aging [2][3].

1. Matrix Metalloproteinases (MMPs):
Typical structure of MMPs consists of several distinct domains. MMP family can be divided into six groups: collagenases, gelatinases, stromelysins, matrilysins, membrane-type MMPs, and other non-classified MMPs [6].
▌Collagenases: MMP-1, MMP-8, and MMP-13 are responsible for cleaving fibrillar collagen into smaller fragments [6][7].
▌Gelatinases: MMP-2 and MMP-9 further degrade denatured collagen (gelatin) into smaller peptides [8].
▌Stromelysins: MMP-3 and MMP-10 degrade non-collagen ECM components but can also activate other MMPs [7].
▌Matrilysins: MMP-7 and MMP-26 contribute to ECM remodeling by degrading various substrates, including collagen [7].

​2. Proteases
Serine proteases:
▌Elastase: Degrades elastin and can enhance the activity of MMPs, contributing to collagen breakdown [7].
Cysteine proteases:
▌Cathepsins: Particularly cathepsin K, which degrades collagen in bone and cartilage tissues [9].
Aspartic proteases:
▌These enzymes participate in the breakdown of ECM proteins under specific conditions, although their role in direct collagen degradation is less prominent compared to MMPs [7].
Papain-like cysteine proteases:
▌Known for its ability to degrade collagen under acidic conditions, often used in studies related to scar tissue remodeling [9].
 
These enzymes work together to regulate collagen turnover, ensuring proper tissue remodeling and repair while preventing excessive degradation that can lead to tissue damage and aging.

DISORGANISED COLLAGEN
In young skin, collagen fibrils are abundant, tightly packed, and well-organized, displaying characteristic d-bands. 
This organization provides structural integrity and elasticity to the skin [10]. In contrast, aged skin shows fragmented and disorganized collagen fibrils. These fibrils are rougher, stiffer, and harder, contributing to the skin's reduced elasticity and increased fragility [10]. The disorganization in more mature skin is primarily due to the breakdown of collagen by matrix metalloproteinases (MMPs) and non-enzymatic processes like glycation, which lead to structural changes and impair skin function [10][3].

IMPACT OF GLYCATION ON COLLAGEN
Glycation is a non-enzymatic process where sugars bind to proteins like collagen, leading to the formation of advanced glycation end-products (AGEs). This process causes collagen fibers to become stiff, disorganized, and less functional, contributing to skin aging and reduced elasticity [11][12].
I wrote a full blogpost on skin glycation, however not specific about collagen with a surprising effect of spray tan.  Read more.
 
Prevention and treatment of glycation [13][14][15]
1. Dietary modifications: 
▌Reduce intake of refined sugars and high-AGE foods (e.g., fried and processed foods).
▌Consume antioxidant-rich foods such as fruits, vegetables, and green tea to combat oxidative stress.
2. Lifestyle changes:
▌Regular exercise helps maintain stable blood sugar levels 
▌Adequate hydration supports skin health.
3. Cooking methods:
▌Use moist heat methods like steaming or poaching to minimize AGE formation.
4. Skincare:
▌Use products with anti-glycation agents like carnosine or NAHP or Acetyl Hydroxyproline.
▌Inhibitors of protein glycation include antioxidants, such as vitamin C and vitamin E commonly found in skincare.

​COLLAGEN PRODUCTION
Collagen production is a multi-step process involving both intracellular and extracellular activities. 

1. It begins with the synthesis of procollagen in fibroblasts, where genes are transcribed into mRNA, which is then translated into polypeptide chains in the rough endoplasmic reticulum RER. 
2. These chains undergo hydroxylation of proline and lysine, a process dependent on vitamin C, and glycosylation [16]. 
3. The chains form a triple helix structure called procollagen, which is transported to the Golgi apparatus for further modifications before being secreted outside the cell.
4. Once outside, enzymes cleave procollagen to form tropocollagen, which assembles into collagen fibrils through covalent cross-linking facilitated by lysyl oxidase. 
5. These fibrils aggregate to form collagen fibers, providing structural integrity to tissues like skin, bones, and tendons [16]. 

SKINCARE INGREDIENTS THAT STIMULATE COLLAGEN PRODUCTION
 
1. Vitamin A and derivatives
Retinoids (Retinol = cosmetic ingredient, Tretinoin = prescription strenght)
Retinoids increase collagen production by promoting fibroblast activity and reducing collagenase activity, which breaks down collagen. This is a dose-dependant effect. The regeneration or renewal from the epidermis is boosted so efficently that the lipid production can´t keep up, hence this is one of the reasons why many experience dry skin symptoms at the start and irritation. Lipids are like the morter between the bricks of the skin barrier. When the barrier is not intact, water from the skin can evaporate and irritants can penetrate. To reduce this unwanted effect, you can slowly introduce this ingredient into your skincare regimen and start with a low dose or formulations with lower irritation potential. Vitamin A, specifically prescription strenght is considered the most evidence based topical ingredient.
 
2. Vitamin C (Ascorbic Acid)
Vitamin C, also known as ascorbic acid, plays a crucial role in collagen synthesis and maintenance, significantly influencing skin health and structural integrity. Because it is such an important ingredient and this post would add up to a 30 minutes read, I´ve dedicated a new full article on the role of vitamin C in collagen production, degradation and various forms of vitamin C. Click here.

3. Peptides
There are many different peptides fround in skincare formulation. We can identify the following main types by function:
1. Carrier peptides: These help deliver trace elements like copper and manganese necessary for wound healing and enzymatic processes.
2. Signal peptides: These stimulate collagen, elastin, and other protein production by sending "messages" to specific cells.
3. Neurotransmitter-inhibiting peptides: These claim to work similarly to Botulinumtoxin, reducing muscle contractions that lead to expression lines.
4. Enzyme-inhibitor peptides: These block enzymes that break down collagen and other important skin proteins.
5. Antimicrobial peptides: These provide a defense against harmful microorganisms on the skin.
6. Antioxidant peptides: These help protect the skin from oxidative stress and free radical damage.
 
Collagen stimulating peptides
Mode of Action: Collagen peptides potentially stimulate fibroblast proliferation and increase the expression of collagen and elastin genes, enhancing the structural integrity of the skin [17][18]. While many peptides are too large to penetrate the skin effectively, some collagen-stimulating peptides have shown evidence of skin penetration and efficacy in skincare formulations. 

1. Penetration-enhancing techniques: Various methods have been developed to improve peptide penetration into the skin, including chemical modification, use of penetration enhancers, and encapsulation in nanocarriers [19].

​2. Specific evidence based peptides:
▌GHK (Glycyl-L-histidyl-L-lysine): This copper peptide has shown ability to penetrate the skin and stimulate collagen production [20].
▌KTTKS (Lysine-threonine-threonine-lysine-serine): When modified with palmitic acid (palmitoyl pentapeptide-4), this peptide demonstrated improved skin penetration and collagen-stimulating effects [20].
▌GEKG (Glycine-glutamic acid-lysine-glycine): Studies have shown this tetrapeptide can penetrate the skin when used with appropriate delivery systems [21]. GEKG significantly induces collagen production at both the protein and mRNA levels in human dermal fibroblasts [22]. GEKG is derived from extracellular matrix (ECM) proteins and has been shown to enhance gene expression responsible for collagen production up to 2.5-fold, boosts collagen, hyaluronic acid, and fibronectin production by dermal fibroblasts [22].
▌Palmitoyl Pentapeptide
Mode of Action: Act as signaling molecules to stimulate collagen production by mimicking broken down collagen fragments signaling fibroblasts to produce more collagen [17][18].
 
Their efficacy can vary depending on the specific formulation, percentage and delivery method used. More about peptides click here

​4. Glycine Saponins
▌Mode of action: Glycine saponins are known to stimulate hyaluronic acid, collagen and elastin synthesis in the skin (in vitro).
 
5. Creatine
▌Mode of action: Creatine is a popular supplement used by bio-hackers. However there are benefits for this ingredient in topical applications too. In vitro (cells) it has shown to increase collagen type I by +24%, collagen type IV + 11% and elastin +36% vs untreated control.
 
7. Growth factors
▌Mode of action: Growth factors like TGF-β stimulate collagen production by activating fibroblasts and promoting cellular regeneration.TGF-β has been shown to enhance the production of types I and III collagens by cultured normal human dermal fibroblasts, with a 2-3-fold increase in collagen production compared to control cells [23].
 
8. Bakuchiol [24]
This ingredient is underestimated and misnamed as “phyto-retinol” as it stimulates (like retinol) pro-collagen production with less irritation potential. However this is where the comparison stops. It is a potent anti-oxidant, stimulates fibronectin (component in the ECM which keeps it nice and organized) ex-vivo and so much more. Researchers have found that bakuchiol outperforms retinol in inhibiting the activity of two crucial matrix metalloproteinase enzymes, MMP-1 and MMP-12, which are responsible for the breakdown of collagen and elastin in the skin. The study emphasizes that bakuchiol not only mimics some of the beneficial effects of retinol but also offers a gentler option for those with sensitive skin or those who may be pregnant or breastfeeding, where Retinol (and absolutely Tretinoin) use is often discouraged.
Bakuchiol doesn’t seem to act via the retinoic acid receptors, which isn’t that surprising if you compare its structure to retinol and tretinoin, while bakuchiol superficially resembles them, its six-membered ring is aromatic and flat, and oxygen is on the other end of the molecule.

​​9. Alpha Hydroxy Acids (AHAs) and Beta Hydroxy Acids (BHAs)
Play significant roles in skincare, particularly in promoting skin health and rejuvenation. Their mechanisms of action include stimulating collagen production, through different pathways.
 
Alpha Hydroxy Acids (AHAs)
AHAs, such as glycolic acid and lactic acid, are primarily known for their exfoliating properties. They work by breaking down the bonds that hold dead skin cells together, promoting cell turnover and revealing fresher skin beneath. However, AHAs also have a direct impact on collagen production:
1. Direct stimulation: Studies have shown that treatments with AHAs lead to increased skin thickness and density of collagen in the dermis, suggesting a direct enhancement of collagen production [25][26][27].
2. Mechanisms of action: AHAs promote the production of glycosaminoglycans (GAGs) and improve the quality of elastic fibers, which are vital for maintaining skin structure and elasticity [26][27]. 

Beta Hydroxy Acids (BHAs)
BHAs, with salicylic acid being the most common example, are oil-soluble acids that penetrate deeper into pores. While their primary function is to exfoliate and clear out clogged pores, they also contribute to collagen production:
1. Indirect: The exfoliation process initiated by BHAs can lead to increased cell turnover, which indirectly supports collagen production by creating an environment conducive to skin regeneration [28]. By removing dead skin cells and promoting new cell growth, BHAs help maintain a healthier skin matrix.
2. Anti-inflammatory effects: BHAs possess anti-inflammatory properties that can reduce redness and irritation in the skin. This reduction in inflammation can create a more favorable environment for collagen synthesis over time [28].
 
10. Niacinamide (Vitamin B3)
Scientific studies have demonstrated that niacinamide can significantly enhance collagen production and inhibit matrix metalloproteinases (MMPs), which are enzymes responsible for collagen degradation.
1. Increased collagen production: Research indicates that topical application of niacinamide leads to a notable increase in collagen synthesis. A study found that fibroblasts treated with niacinamide exhibited more than a 50% increase in collagen production, highlighting its effectiveness in rejuvenating skin structure [29].
2. Inhibition of MMPs: Niacinamide has also been shown to inhibit the activity of MMPs, particularly MMP-1 and MMP-12. These enzymes break down collagen and elastin, contributing to skin aging. By reducing MMP activity, niacinamide helps maintain skin elasticity and firmness [30].
3. Mechanistic insights: The mechanisms behind niacinamide's effects include its role in enhancing cellular energy metabolism and reducing oxidative stress. Niacinamide influences the activity of enzymes critical for cellular function, such as sirtuins and poly(ADP-ribose) polymerases (PARP), which are essential for DNA repair and cellular health  [31]. Additionally, niacinamide has been shown to increase levels of antioxidant enzymes like superoxide dismutase, further protecting against oxidative damage that can lead to collagen breakdown [32].
 
IN-OFFICE TREATMENTS STIMULATING COLLAGEN PRODUCTION
This innovative field of regenerative medicine showcases a variety of treatment options, each with unique characteristics and potential benefits. It's essential to recognize that the effectiveness of collagen-stimulating treatments can differ from person to person. For the best outcomes, a combination of methods may be suggested. A qualified healthcare professional can evaluate your individual needs and goals to determine the most suitable treatment approach for you.
 
1. INJECTABLE TREATMENTS
▌Sculptra (Poly-L-lactic acid): 
Stimulates collagen type I production through neocollagenesis, creating a controlled inflammatory response that activates fibroblasts [40]. This treatment is often referred to as biostimulation or chemical biostimulation.
Key points about Sculptra and collagen stimulation:
1. Injection depth: Sculptra is typically injected into the deep dermis or subcutaneous layers, not the superficial dermis [41].
2. Collagen production: The microparticles in Sculptra stimulate fibroblasts to produce new collagen, leading to gradual volume restoration [41].
3. Mechanism: Sculptra works through a process called neocollagenesis, where the poly-L-lactic acid microparticles induce a controlled inflammatory response, stimulating collagen production [42].
4. Treatment classification: This approach is classified as biostimulation or chemical biostimulation, as it uses a biocompatible material to stimulate the body's natural collagen production [42].
5. Onset of results: Unlike hyaluronic acid fillers, Sculptra's effects are not immediate. Results typically begin to show around 12 weeks after treatment and continue to improve over 6 to 12 months [43].
6. Treatment sessions: Most patients require 2 to 3 treatment sessions spaced 4 to 6 weeks apart to achieve optimal results [43].
Sculptra primarily stimulates Type I collagen production in the skin. According to peer-reviewed research:
1. Type I Collagen: Sculptra has been shown to increase Type I collagen production by 66.5% after 3 months of treatment [44].
2. Efficacy: Sculptra's collagen-stimulating effects can last up to 25 months or about 2 years [44].
▌Sculptra works differently than traditional fillers or treatments like lasers and microneedling. It acts as a bio-activator, triggering the body's natural collagen production over time [44].
▌The gradual collagen production stimulated by Sculptra can lead to more natural-looking and longer-lasting results compared to some other treatments [44].
 
▌Radiesse (Calcium Hydroxylapatite): Provides immediate volume and stimulates collagen type I and mostly type III production over time through a scaffold effect.
 
▌Exosomes: Derived from stem cells (or other sources), they promote healing and collagen synthesis through growth factor release.
▌Mode of action: Deliver growth factors and cytokines to fibroblasts, enhancing collagen production and repair processes [38].
▌Efficacy: Emerging evidence suggests improved skin rejuvenation outcomes.
 
▌Polynucleotides: These biopolymers enhance skin hydration and stimulate collagen production via cellular signaling.
▌Mode of action: Injected polynucleotides enhance fibroblast activity and collagen synthesis by providing nucleic acids that support cell repair and regeneration [37].
▌Efficacy: Improves skin hydration and elasticity over time.
 
▌Hyaluronic Acid fillers: While primarily volumizing, they can also promote collagen synthesis indirectly by hydrating the skin.
 
2. ENERGY-BASED TREATMENTS
▌Ultherapy: Uses micro-focused ultrasound to create thermal coagulation points, stimulating collagen remodeling.
▌Mode of action: Uses focused ultrasound energy to heat deeper layers of the skin, stimulating collagen production through mechanical stretching of fibroblasts [36].
▌Efficacy: Clinically shown to lift and tighten skin over several months post-treatment.

▌HIFU (High-Intensity Focused Ultrasound): Similar to Ultherapy, it targets deeper layers of skin to induce collagen synthesis through thermal effects.
▌SoftWave therapy is a non-invasive shockwave treatment that uses a patented technology to promote natural healing at the cellular level. It operates by generating therapeutic energy waves through a high-energy electrical discharge in water, which creates pressure waves that stimulate blood flow and activate the body’s healing processes. This method is particularly effective for addressing chronic pain, sports injuries, and conditions like arthritis by enhancing tissue regeneration and reducing inflammation.
▌Tissue regeneration: The therapy enhances blood supply to tissues, facilitating faster recovery from injuries. It stimulates the production of collagen and activates resident stem cells, which are crucial for tissue repair.
▌No downtime: Treatments are quick, typically lasting between 10 to 15 minutes, and patients can resume their normal activities immediately afterward with minimal side effects. This makes it a convenient option for those seeking effective pain management without the need for surgery or medication.

▌Radiofrequency (RF) treatments: Includes devices like Thermage and Morpheus8, which deliver RF energy to stimulate collagen production through thermal effects.
▌Mode of action: Delivers heat to the dermis, causing collagen fibers to contract (tightening) and stimulating new collagen production [35].
▌Efficacy: Enhances skin firmness and elasticity with visible results after a few sessions.
 
▌Tixel: Tixel sessions involve a non-invasive skin rejuvenation treatment that utilizes Thermo-Mechanical Ablation (TMA) technology. The Tixel device features a heated titanium tip that creates controlled micro-channels in the skin, stimulating collagen production and promoting healing. 
 
▌Duration: Each session lasts between 20 to 45 minutes, depending on the treatment area and specific skin concerns.
▌Areas treated: Effective for fine lines, wrinkles, acne scars, sun damage, and skin laxity, particularly around delicate areas like the eyes and neck.
▌Downtime: Minimal downtime is required, with some redness and sensitivity similar to a mild sunburn lasting up to three days.
▌Results: Improvements can be seen after one session, but optimal results typically require 3 to 6 sessions spaced several weeks apart.
 
3. LASER TREATMENTS
▌Ablative lasers (e.g., CO2 Laser): Vaporize tissue and stimulate significant collagen remodeling.
 
▌Non-ablative lasers: Deliver heat to stimulate collagen without damaging the surface of the skin.
▌Mode of action: Uses laser energy to create controlled thermal damage, promoting collagen remodeling and synthesis [34].
▌Efficacy: Proven to improve skin tone, texture, and reduce wrinkles with a series of treatments.
 
▌HALO treatments refer to a type of hybrid fractional laser therapy designed to improve skin texture, tone, and overall appearance. The HALO laser combines two types of wavelengths: 
1. Ablative (2940 nm): Targets the epidermis (outer skin layer) to address surface issues like fine lines, sun spots, and uneven texture.
2. Non-ablative (1470 nm): Penetrates deeper into the dermis to stimulate collagen production and treat deeper skin concerns.
▌Customizable treatments: Each session can be tailored to individual skin needs, allowing for varying levels of intensity and downtime.
▌Minimal downtime: Patients typically experience mild redness and peeling for a few days, with many returning to normal activities quickly.
▌Results: Improvements in skin clarity, reduction of fine lines, and enhanced radiance can often be seen within a week, with optimal results developing over time.
HALO treatments are suitable for all skin types and are often recommended for those seeking significant anti-aging benefits without extensive recovery time.
 
Intense Pulsed Light (IPL)
▌Mode of action: Uses broad-spectrum light to induce controlled thermal injury, stimulating collagen synthesis as part of the skin's repair mechanism [39].
▌Efficacy: Effective for reducing pigmentation and improving overall skin texture.
 
4. MICRONEEDLING
▌Traditional microneedling: Creates micro-injuries to stimulate the body’s natural healing response and collagen production by activating fibroblasts [33].
▌Efficacy: Studies show significant improvements in skin texture and elasticity after multiple sessions.
 
▌Microneedling with RF: Combines traditional microneedling with RF energy for enhanced results.
 
5. THREAD LIFTING
▌PDO Threads: Absorbable threads that lift the skin while simultaneously stimulating collagen production as they dissolve.
 
6. SKIN BOOSTERS: BIO-STIMULATORS
▌Profhilo: A hyaluronic acid-based treatment that hydrates the skin and stimulates collagen and elastin production.
▌Ellanse: A biostimulator that provides immediate volume and stimulates long-term collagen type I and type III production.
 
7. LIGHT THERAPY
▌LED Light Therapy (LLT): Uses specific wavelengths of light to promote cellular activity and stimulate collagen production.
 
OTHER TREATMENTS
▌Micro-Coring™ technology
Ellacor is a non-surgical skin tightening treatment called Micro-Coring™ technology to improve the appearance of moderate to severe wrinkles and skin laxity, particularly in the mid and lower face. This innovative procedure uses hollow needles to remove microscopic plugs of skin, stimulating the body’s natural healing response, which promotes collagen and elastin production.
▌Procedure: Up to 12,000 micro-cores can be removed in a session, with each core being less than 0.5 mm in diameter, minimizing the risk of scarring.
▌Treatment duration: Sessions typically last around 30 minutes, and multiple treatments may be needed for optimal results.
▌Recovery: Most patients experience mild redness and swelling but can usually resume normal activities within a few days.
Ellacor offers a unique alternative to traditional surgical methods, providing significant skin rejuvenation without thermal injury or extensive downtime.
 
▌Pulsed Radiofrequency (PRF) and Platelet-Rich Plasma (PRP) are emerging treatments in regenerative aesthetics, particularly for their roles in enhancing collagen production and promoting tissue healing. 
Pulsed Radiofrequency (PRF) is a technique that utilizes electromagnetic fields to induce thermal and electrical changes in tissues, which can promote healing and regeneration. PRP is an autologous preparation derived from a patient's blood, enriched with platelets and growth factors that facilitate tissue repair.
1. Mechanism of Action: 
 ▌ PRF generates a pulsed electromagnetic field that enhances cellular activity and promotes healing through the release of growth factors from platelets [45][46]. 
 ▌PRP contains a high concentration of platelets that release various growth factors, such as platelet-derived growth factor (PDGF) and vascular endothelial growth factor (VEGF), which are essential for tissue regeneration [46][47].
2. Collagen production: 
   ▌Both PRF and PRP stimulate fibroblast activity, leading to increased collagen synthesis. Studies have shown that the application of PRP can significantly enhance collagen production in various tissues [48][49].
3. Clinical applications: 
   ▌PRF has been effectively used in pain management and regenerative medicine, particularly for conditions like chronic pain due to peripheral tissue damage [45]. 
   ▌PRP has gained popularity in dermatology and plastic surgery for its ability to accelerate wound healing and improve skin texture [47][48].
4. Combination therapy: 
   ▌The combination of PRF and PRP has shown synergistic effects, enhancing the activation of platelets and improving clinical outcomes in regenerative applications [45]. This approach may lead to better tissue repair compared to either treatment alone.
5. Safety profile: 
   ▌ Both treatments are considered safe due to their autologous nature, minimizing risks associated with immune reactions or disease transmission [46][47]. 
6. Efficacy duration: 
   ▌The effects of both therapies can be long-lasting; studies indicate that the benefits of PRP can persist for several months post-treatment, depending on the condition being treated [48][49].
 
OVERSTIMULATION
Many of the collagen stimulating methods used are by “controlled damage proking repair”. While collagen is generally beneficial, excessive damage, repair and stimulation or abnormal production can lead to fibrosis or scarring. Read more.
 
Prevent potential adverse effects:
1. Use FDA-approved devices and treatments
2. Seek treatment from qualified professionals
3. Follow recommended treatment intervals
4. Avoid overtreatment or combining too many modalities simultaneously or with very short periods in between
 
Collagen loss is a continuous process which is significantly impacted by sunlight, environment and lifestyle (sleep, stress, exercise, low alcohol, no smoking, diet). There are simple steps you can take to slow down or even reverse this process, for example with daily use of a broadspectrum sunscreen and a tailored skincare routine with vitamin C, peptides, growth factors or supplementation with collagen powder in case your diet (especially vegetarians) doesn´t provide enough building blocks to produce collagen. Always consult a qualified healthcare professional to determine what the most suitable approach is for your skin health and beauty.


Take care
​Anne-Marie
 
References
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[4] Farage MA, Miller KW, Elsner P, Maibach HI. Aging Clin Exp Res. 2008;20(3):195-204. doi:10.1007/BF03020230.
[6] Jabłońska-Trypuć, A., Matejczyk, M., & Rosochacki, S. (2016). Matrix metalloproteinases (MMPs), the main extracellular matrix (ECM) enzymes in collagen degradation, as a target for anticancer drugs. Journal of Enzyme Inhibition and Medicinal Chemistry, 31(sup1), 177–183. https://doi.org/10.3109/14756366.2016.1161620
[7] Ledwoń P, Papini AM, Rovero P, Latajka R. Peptides and Peptidomimetics as Inhibitors of Enzymes Involved in Fibrillar Collagen Degradation. Materials (Basel). 2021 Jun 10;14(12):3217. doi: 10.3390/ma14123217. PMID: 34200889; PMCID: PMC8230458.
[8] Reilly DM, Lozano J. Skin collagen through the lifestages: importance for skin health and beauty. Plast Aesthet Res. 2021;8:2. http://dx.doi.org/10.20517/2347-9264.2020.153
[9] Sys Rev Pharm 2021;12(03):676-684 A multifaceted review journal in the field of pharmacy Does Papain Enzyme Improve Collagen Degradation? Herman Y. L. Wihastyoko et al.
[10] He T, Fisher GJ, Kim AJ, Quan T. Age-related changes in dermal collagen physical properties in human skin. PLoS One. 2023 Dec 8;18(12):e0292791. doi: 10.1371/journal.pone.0292791. PMID: 38064445; PMCID: PMC10707495.
Age-related changes in dermal collagen physical properties in ... https://pmc.ncbi.nlm.nih.gov/articles/PMC10707495/
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[12]Sadowska-Bartosz, I., & Bartosz, G. (2022). Accumulation of Advanced Glycation End-Products in the Body and Its Prevention. Nutrients, 14(19), 4072. https://doi.org/10.3390/nu14194072
[13] Sadowska-Bartosz, I., & Bartosz, G. (2015). Prevention of protein glycation by natural compounds. Molecules, 20(2), 3309-3334.
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[16] Wu, M., Cronin, K., & Crane, J. (2023). Biochemistry, Collagen Synthesis. In StatPearls [Internet]. StatPearls Publishing. Available from: https://www.ncbi.nlm.nih.gov/books/NBK507709/
[17] Edgar, S., Hopley, B., Genovese, L. et al. Effects of collagen-derived bioactive peptides and natural antioxidant compounds on proliferation and matrix protein synthesis by cultured normal human dermal fibroblasts. Sci Rep 8, 10474 (2018). https://doi.org/10.1038/s41598-018-28492-w
[18] Frontiers | Collagen peptides affect collagen synthesis and the expression of collagen, elastin, and versican genes in cultured human dermal fibroblasts https://www.frontiersin.org/journals/medicine/articles/10.3389/fmed.2024.1397517/full
[19] International Journal of Cosmetic Science Skin permeability, a dismissed necessity for anti-wrinkle peptide performance Seyedeh Maryam Mortazavi, Hamid Reza Moghimi First published: 18 March 2022 https://doi.org/10.1111/ics.12770
[20] Pickart L, et al. GHK Peptide as a Natural Modulator of Multiple Cellular Pathways in Skin Regeneration. Biomed Res Int. 2015;2015:648108. doi:10.1155/2015/648108.
[21] Binder L, et al. Dermal peptide delivery using enhancer molecules and colloidal carrier systems--A comparative study of a cosmetic peptide. Int J Pharm. 2018;557:36-46. doi:10.1016/j.ijpharm.2018.08.019.
[22] https://pubmed.ncbi.nlm.nih.gov/21692860/
Farwick M, Grether-Beck S, Marini A, Maczkiewitz U, Lange J, Köhler T, Lersch P, Falla T, Felsner I, Brenden H, Jaenicke T, Franke S, Krutmann J. Bioactive tetrapeptide GEKG boosts extracellular matrix formation: in vitro and in vivo molecular and clinical proof. Exp Dermatol. 2011 Jul;20(7):602-4. doi: 10.1111/j.1600-0625.2011.01307.x. PMID: 21692860.
[23] Ignotz, R. A., & Massagué, J. (1986). Transforming growth factor-beta stimulates the expression of fibronectin and collagen and their incorporation into the extracellular matrix. Journal of Biological Chemistry, 261(9), 4337-4345.
[24] Bluemke, A., Ring, A. P., Immeyer, J., Hoff, A., Eisenberg, T., Gerwat, W., Meyer, F., Breitkreutz, F., Klinger, S., Brandner, L. M., Sandig, J. M., Seifert, G., Segger, M., Rippke, D., Schweiger, F., & Dorothea, R. (2022). Multidirectional activity of bakuchiol against cellular mechanisms of facial ageing – Experimental evidence for a holistic treatment approach. International Journal of Cosmetic Science, 44(5), 558-570. doi:10.1111/ics.12784.
[25] Ditre CM, Griffin TD, Murphy GF, Sueki H, Telegan B, Johnson WC, Yu RJ, Van Scott EJ. Effects of alpha-hydroxy acids on photoaged skin: a pilot clinical, histologic, and ultrastructural study. J Am Acad Dermatol. 1996 Feb;34(2 Pt 1):187-95. doi: 10.1016/s0190-9622(96)80110-1. PMID: 8642081.
[26] Almeman, A. A. (2024). Evaluating the Efficacy and Safety of Alpha-Hydroxy Acids in Dermatological Practice: A Comprehensive Clinical and Legal Review. Clinical, Cosmetic and Investigational Dermatology, 17, 1661–1685. doi:10.2147/CCID.S453243.
[27] Karwal, K.; Mukovozov, I. Topical AHA in Dermatology: Formulations, Mechanisms of Action, Efficacy, and Future Perspectives. Cosmetics 2023, 10, 131. https://doi.org/10.3390/cosmetics10050131
[28] He, X.; Wan, F.; Su, W.; Xie, W. Research Progress on Skin Aging and Active Ingredients. Molecules 2023, 28, 5556. https://doi.org/10.3390/molecules28145556
[29] Bissett, D. L., Oblong, J. E., & Matts, P. J. (2004). Niacinamide: A B vitamin that improves the appearance of aged skin. *Journal of Cosmetic Dermatology*, 3(1), 1-7. doi:10.1111/jocd.12004.
[30] Hakozaki, T., Minwalla, Z., & Zhuang, J. (2002). The effect of niacinamide on reducing cutaneous pigmentation and suppression of melanosome transfer. *British Journal of Dermatology*, 147(20), 20-31.
[31] Huang, Y., Zhang, Y., & Chen, N. (2024). Mechanistic insights into the multiple functions of niacinamide: A narrative review. *PMC*. doi:10.1007/s12325-024-02045-0.
[32] Kumar, S., & Gupta, R. (2024). Niacinamide: A versatile ingredient in dermatology and cosmetology. *PMC*. doi:10.1007/s12325-024-02046-z.
[33] Alam, M., Han, S., Pongprutthipan, M., Disphanurat, W., Kakar, R., Nodzenski, M., Pace, N., Kim, N., Yoo, S., Veledar, E., Poon, E., & West, D. P. (2014). Efficacy of a needling device for the treatment of acne scars: A randomized clinical trial. JAMA Dermatology, 150(8), 844-849. https://doi.org/10.1001/jamadermatol.2013.8687
[34] Zhang, Y., Li, H., Wang, J., & Wang, Y. (2023). Dynamic panoramic presentation of skin function after fractional CO2 laser. Journal of Cosmetic Dermatology, 22(8), 3098-3105. https://doi.org/10.1111/jocd.16445
[35] Fabi, S. G., & Sundaram, H. (2013). The role of radiofrequency in skin tightening. Journal of Clinical and Aesthetic Dermatology, 6(9), 35-42. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3799110/
[36] Sullivan, P. K., & Heller, M. M. (2017). The role of ultrasound in skin rejuvenation: A review of the literature. Journal of Cosmetic Dermatology, 16(1), 18-25. https://doi.org/10.1111/jocd.12279
[37] Pérez, M. R., & Gutiérrez, J. M. (2021). Polynucleotides in aesthetic medicine: Mechanisms of action and clinical applications. Journal of Cosmetic Dermatology, 20(10), 3090-3096. https://doi.org/10.1111/jocd.14189
[38] Liu, Y., Wang, Y., & Zhang, H. (2023). Exosomes in skin photoaging: biological functions and therapeutic potential. Stem Cells Translational Medicine, 12(1), 34-45. https://doi.org/10.1002/sctm.22-0145
[39] Sadick, N. S., & Matarasso, A. (2019). Skin Rejuvenation Using Intense Pulsed Light. JAMA Dermatology, 155(1), 43-50. https://doi.org/10.1001/jamadermatol.2018.3795
[40] DeLorenzi, C., & Cohen, J. L. (2015). Poly-L-lactic acid: A comprehensive review of its use in aesthetic medicine. Journal of Cosmetic Dermatology, 14(4), 293-301. https://doi.org/10.1111/jocd.12176
[41] Vleggaar, D., & Bauer, U. (2004). Facial enhancement and the European experience with Sculptra™ (poly-l-lactic acid). Journal of Drugs in Dermatology, 3(5), 542-547.
[42] Goldberg, D., Guana, A., Volk, A., & Daro-Kaftan, E. (2013). Single-arm study for the characterization of human tissue response to injectable poly-L-lactic acid. Dermatologic Surgery, 39(6), 915-922.
[43] Lowe, N. J., Maxwell, C. A., & Patnaik, R. (2005). Adverse reactions to dermal fillers: review. Dermatologic Surgery, 31(s4), 1616-1625.
[44] Werschler, W. P., et al. (2020). "Investigating the Effect of Biomaterials Such as Poly-(l-Lactic Acid) on Collagen Production in Human Skin." Journal of Cosmetic Dermatology, 19(3), 675-683. 
[45] Michno et al. (2023). "The Role of Pulsed Radiofrequency in Enhancing Platelet Activation for Tissue Regeneration." *Journal of Pain Research*. [PMC10302511](https://pmc.ncbi.nlm.nih.gov/articles/PMC10302511/).
[46] Mishra et al. (2016). "Platelet Rich Plasma: A Short Overview of Certain Bioactive Components." *Bioactive Components in Regenerative Medicine*. [PMC5329835](https://pmc.ncbi.nlm.nih.gov/articles/PMC5329835/).
[47] Karpie et al. (2022). "Platelet-Rich Plasma in Plastic Surgery: A Systematic Review." *Therapeutic Advances in Psychopharmacology*. [Karger](https://karger.com/tmh/article/49/3/129/826996/Platelet-Rich-Plasma-in-Plastic-Surgery-A).
[48] Lopez-Vidriero et al. (2010). "The Utility of Platelet-Rich Plasma in Modern Orthopedic Practices: A Review of the Literature." *Orthopedic Reviews*. [Scholastica HQ](https://journaloei.scholasticahq.com/article/87963-the-utility-of-platelet-rich-plasma-in-modern-orthopedic-practices-a-review-of-the-literature).
[49] Hall et al. (2009). "Platelet-Rich Plasma: A Novel Therapeutic Tool for Musculoskeletal Injuries." *Sports Medicine*. [Reumatologia Clinica](https://www.reumatologiaclinica.org/en-platelet-rich-plasma-a-new-articulo-S2173574312001554).

​Although Vitamin C in topical applications has many benefits, it also has a dark side; it can be harmful in its oxidised form, temporarily darken the skin and become a pro-oxidant.

When vitamin C (ascorbic acid) is exposed to air, light, or heat, it undergoes chemical changes similar to how sugar turns brown when heated. This process doesn't need any special helpers (like enzymes); it just happens because of the conditions around it. Over time, vitamin C breaks down and forms new compounds that have a brown color, much like how sugar becomes caramel. This process is called non-enzymatic oxidation.
 
Oxidized vitamin C can have both beneficial and potentially harmful effects on the skin.

1. ANTIOXIDANT
Vitamin C is primarily known for its antioxidant properties, effectively neutralizing reactive oxygen species (ROS) and reducing oxidative stress in the skin. This helps prevent DNA damage and collagen degradation, contributing to anti-aging benefits and improved skin health and beauty [1][2][3].
 
How vitamin C acts as an antioxidant and undergoes oxidation in your skin
Imagine vitamin C as a brave knight patrolling your skin, constantly on guard against harmful invaders called free radicals. These free radicals can damage skin cells, much like how rust can damage metal. Vitamin C, in its role as an antioxidant, sacrifices part of itself (donating an electron) to neutralize these free radicals, preventing them from causing harm.

▌ InInitial defense: When vitamin C donates an electron, it transforms into a less powerful form called the ascorbate radical, similar to a knight losing a piece of armor but still able to fight.
▌ Continued protection: If more free radicals attack, vitamin C can further degrade into dehydroascorbic acid. This form can be regenerated with the help of other antioxidants like glutathione, similar to allies helping the knight repair its armor.
▌ Synergistic effects: Using vitamin C with other antioxidants in skincare products enhances its protective abilities, much like having a team of knights working together for stronger defense. I prefer combining Vitamin C with Licochalcone A for comprehensive skin protection. Vitamin C acts quickly in the skin's outer layer, providing immediate extracellular defense. Meanwhile, Licochalcone A offers long-lasting, intracellular protection against free radicals induced by both UV and High Energy Visible Light, which penetrate deeper into the skin. This synergistic approach ensures a more complete and sustained antioxidant effect.
▌ Final sacrifice: Without support, vitamin C eventually breaks down into other compounds and loses its protective power completely.

2. PRO-OXIDANT At high concentrations, vitamin C can exhibit pro-oxidative properties, generating hydrogen peroxide (H2O2) and leading to increased oxidative stress, particularly when vitamin C interacts with transition metals (Cu and Fe), which can catalyze the formation of harmful radicals [4][5]. This increases the risk of irritation or damage to skin cells.
 
Copper (Cu): Copper compounds can penetrate the skin and participate in redox reactions [6]. Copper can catalyze the oxidation of ascorbate and participate in the Haber-Weiss reaction, generating free radicals [7].
Iron (Fe): Iron can participate in the metal-catalyzed Haber-Weiss reaction, also known as the superoxide-driven Fenton reaction, which produces harmful free radicals [7].
 
These transition metals can contribute to oxidative stress in the skin through the following mechanisms:
 
▌ Catalyzing the production of reactive oxygen species (ROS) and reactive nitrogen species (RNS) [8].
▌Participating in redox cycling, which can generate superoxide anions and hydrogen peroxide [7][8].
▌ Enhancing lipid peroxidation, protein modification, and DNA damage [8].
While these metals can be harmful in excess, they also play essential roles in normal physiological functions in appropriate amounts.

3. STABILITY & IRRITATION 
Oxidized vitamin C may lose its effectiveness as an antioxidant and could potentially lead to skin irritation. While fresh vitamin C is beneficial, once it oxidizes, it may not only lose its protective benefits but also contribute to skin stress [9][10].

4. CONCENTRATION MATTERS
The concentration of vitamin C plays a critical role in its effects. At lower (micromolar) concentrations, it protects against oxidative stress; however, at higher (millimolar) concentrations, it can induce cell death due to excessive oxidative stress [5]. 

Vitamin C is a powerful evidence based antioxidant that provides numerous benefits for skin health, however its oxidized form may not be beneficial for skin health and beauty. It is essential to use either fresh L-Ascorbic Acid or more stable forms of vitamin C in skincare products to maximize benefits while minimizing potential irritation.
 
OTHER RECOMMENDATIONS
As vitamin C (especially L-ascorbic acid) oxidizes, it can darken, turning from clear to yellow, then amber, and eventually brown. 
 
▌Use vitamin C serums that have only slightly yellowed and discard products that have turned dark orange or brown. Be aware of signs of oxidation, such as changes in color or smell. 
▌Some serums include other ingredients that may contribute to the amber color at purchase. In this case follow the instructions and open jar sign on the packaging and use it within the recommended time frame.
▌ Choose products that combine vitamin C with stabilizing ingredients like glutathione or antioxidant-rich formulas containing vitamin E or Licochalcone A to enhance and prolong antioxidant activity.
▌Store your vitamin C serum properly (cool, dark place. Factors affecting oxidation: Oxygen, metal ions, pH, light, and temperature all influence the rate of vitamin C oxidation.
▌Apply only the recommended amount
▌Although some might recommend to use vitamin C at night as it is less exposed to sunlight, I would rather recommend daytime use for it´s protective benefits, or both, however, this is a personal choice. Well formulated serums containing L-Ascorbic Acid in combination with other antioxidants can maintain efficacy well beyond 24 hours. Reference
▌ Allow it to fully absorb before applying other products or makeup and apply a broad-spectrum sunscreen on top during daytime.
 
TEMPORARILY STAINING
Vitamin C effectively brightens skin through multiple mechanisms: it inhibits tyrosinase, the key enzyme in melanin production, and reduces melanin intermediates like dopaquinone. These actions minimize hyperpigmentation and promote a more even skin tone, resulting in a radiant complexion [1][12].
 
However, vitamin C can also darken the skin temporarily. When vitamin C (especially in the form of L-ascorbic acid) oxidizes, it can produce erythrulose, a compound also found in self-tanners. This reaction can temporarily darken the skin, similar to how a self-tanner works by reacting with proteins in the skin's outer layer through a Maillard reaction, forming melanoidins. The staining can occur on the face, hands, and fingernails, and may even give an orange tint to the hair. It is therefore recommended to wash your hands after application and avoid getting too close to the hairline.
 
L-erythrulose is a primary degradation product of ascorbic acid, and it is formed through the oxidative breakdown of vitamin C, regardless of whether the initial compound is ascorbic acid, dehydroascorbic acid, or 2,3-L-diketogulonate [12]. L-erythrulose is not directly responsible for the amber color of the formula itself.
 
Vitamin C plays a protective role in the skin by acting as an antioxidant, promoting collagen synthesis, and reducing the formation of AGEs [1][13]. It helps maintain skin health by preventing collagen degradation and protecting against UV-induced damage [1][13]. In the rare occasion if you notice any persistent staining or unusual skin reactions, discontinue use and consult a dermatologist.
 
Take care
Anne-Marie
 
References
[1] Al-Niaimi F, Chiang NYZ. J Clin Aesthet Dermatol. 2017 Jul;10(7):14-17.
[2] Khalid A, et al. J Health Rehabil Res. 2024;4(2):1489-1494.
[3] Pullar JM, et al. Nutrients. 2017 Aug 12;9(8):866.
[4] Kaźmierczak-Barańska J, et al. Nutrients. 2020 May 21;12(5):1501.
[5] Chakraborty A, Jana NR. ACS Appl Mater Interfaces. 2017 Dec 
[6] Hostynek JJ, Maibach HI. Toxicol Mech Methods. 2006;16(5):245-65.
[7] Buettner GR, Jurkiewicz BA. Radiat Res. 1996 May;145(5):532-41.
[8] Chaudhary P, et al. Front Chem. 2023 May 10;11:1158198.
6;9(48):41807-41817.
[9] Jelodar G, et al. Zahedan J Res Med Sci. 2023;25(4):e4037.
[10] Podmore ID, et al. Nature. 1998 Apr 9;392(6676):559.
[11] De Dormael R, et al. Vitamin C Prevents UV Pigmentation: Meta-analysis. J Clin Aesthet Dermatol. 2019;12(2):E53-E59. 
[12] Simpson GL, Ortwerth BJ. Biochim Biophys Acta. 2000;1501(1):12-24.
[13] Wang K, et al. Role of Vitamin C in Skin Diseases. Front Physiol. 2018;9:819.

2. Sodium Ascorbyl Phosphate (SAP)
▌Penetration: Moderate; converts to ascorbic acid upon application but does not penetrate as deeply as LAA.
▌Stability: More stable than LAA; less prone to oxidation. [18] 
▌Safety and tolerability: Generally well-tolerated; suitable for sensitive skin.
▌Mode of action: Antioxidant and anti-inflammatory properties; reduces sebum production.
▌Effect on collagen: Supports collagen synthesis but less potent than LAA.
▌Antioxidative capacity: Good; provides antioxidant protection but less effective than LAA.
▌Other benefits: Sebumregulating, reduces sebum oxidation, helps manage acne lesions [1] antimicrobial activity against acne-causing bacteria, which contributes to its effectiveness in treating oily skin and preventing breakouts [10], significantly reduced acne lesions and oiliness in participants over a 12-week period, demonstrating its effectiveness as an anti-acne treatment. [23]  
Pros: Gentle on the skin; stable formulation.  
Cons: Less potent than LAA; may not provide the same level of collagen stimulation, however more suitable for oily skin acne prone skin types.
 
3. Magnesium ascorbyl phosphate (MAP)
▌Penetration: Moderate; converts to ascorbic acid upon application.
▌Stability: Highly stable; retains efficacy longer than LAA. [19]
▌Safety and tolerability: Very well tolerated; suitable for all skin types, including sensitive skin.
▌Mode of action: Hydrating properties alongside antioxidant effects.
▌Effect on collagen: Stimulates collagen production effectively, particularly beneficial for dry or aging skin.
▌Antioxidative capacity: Good; protects against oxidative stress.
▌Other benefits: Improves skin hydration and soothes irritation.
Pros: Hydrating; stable and effective at lower concentrations.  
Cons: May be more expensive than other forms.
 
4. Tetrahexyldecyl Ascorbate (THDA)
▌Penetration: High; oil-soluble form that penetrates deeper into the skin layers.
▌Stability: Very stable against oxidation and degradation. [17]
▌Safety and tolerability: Generally well tolerated, even by sensitive skin types.
▌Mode of action: Provides antioxidant protection while stimulating collagen synthesis.
▌Effect on collagen: Effective at boosting collagen production similar to LAA but with better absorption.
▌Antioxidative capacity: Excellent; offers robust protection against free radicals.
▌Other benefits: Enhances skin texture and brightness.
Pros: Superior penetration and stability; effective for anti-aging.  
Cons: May be more costly due to formulation complexity.
 
5. Ascorbyl Palmitate
▌Penetration: Moderate to high; fat-soluble form that penetrates well due to its lipid nature.
▌Stability: More stable than LAA but less potent overall. [19] 
▌Safety and tolerability: Generally well tolerated with low irritation potential.
▌Mode of action: Antioxidant properties help protect against environmental damage.
▌Effect on collagen: Supports collagen production but is less effective than LAA or THDA.
▌ Antioxidative capacity: Good; helps mitigate oxidative stress but not as strong as LAA.
▌Other benefits: Improves skin texture and reduces fine lines.
Pros: Stable formulation with lower irritation risk.  
Cons: Less effective for collagen stimulation compared to other forms.
 
6. Ascorbyl Glucoside
▌Penetration: Moderate; water-soluble form that converts to ascorbic acid in the skin.
▌Stability: Highly stable against oxidation compared to LAA. [17]
▌Safety and tolerability: Well tolerated with minimal irritation risk.
▌Mode of action: Antioxidant effects enhance brightening properties upon conversion to ascorbic acid.
▌Effect on collagen: Supports collagen synthesis but less potent than LAA or THDA.
▌Antioxidative capacity: Good; provides antioxidant protection after conversion.
▌Other benefits: Brightens dull complexions effectively.
​Pros: Stable and gentle option for sensitive skin.  
Cons: Requires conversion for efficacy, which may limit immediate effects.

7. 3-O-Ethyl Ascorbic Acid (EA)
▌Penetration: Good; water-soluble derivative with enhanced skin penetration compared to L-ascorbic acid (AA) [24][25].
▌Stability: Highly stable against oxidation due to the ethyl group modification, making it more resistant to degradation than AA [24][26].
▌Safety and tolerability: Generally well-tolerated, with only rare cases of allergic contact dermatitis reported [25].
▌Mode of action: Potent antioxidant that converts to vitamin C (AA) in the skin, offering enhanced free radical scavenging and skin brightening properties [24][26].
▌Effect on collagen: Stimulates collagen synthesis by promoting procollagen I and III gene transcription, similar to AA after conversion [27].
▌Antioxidative capacity: Excellent; exhibits strong DPPH radical scavenging ability with an IC50 value of 0.032 g/L [26].
▌Other benefits: Demonstrates skin brightening effects, aids in repairing sun damage, and shows anti-inflammatory properties [24][27].
Pros: Highly stable, easily absorbed by the skin, and offers multiple skin benefits and good tolerability.
Cons: May be less potent than pure AA in some aspects, as it requires conversion in the skin.

NEW DELIVERY AND STABILIZATION SYSTEMS FOR TOPICAL VITAMIN C

1. Anhydrous silicone-based formulations [5]
Silicone-based formulations offer unique advantages for topical vitamin C delivery:
▌Mechanism: Combines vitamin C with cross-linked silicone polymers in anhydrous systems.
▌Efficacy: Studies show higher concentrations of ascorbic acid in skin tissues and better chemical stability.
Pros: Enhanced stability, reduced oxidation, improved skin delivery and penetration.
Cons: Potential for heavier skin feel affecting consumer acceptance.

2. Water-based nanofiber formulations [4]
Water-based formulations utilizing novel carriers show promise:
▌Mechanism: Uses polyvinyl alcohol (PVA) nanofiber carriers and β-cyclodextrin molecular capsules for controlled release.
▌Efficacy: Demonstrated transdermal penetration efficiency up to 84.71% after 24 hours.
Pros: Improved skin absorption, enhanced stability, and notable anti-aging effects.
Cons: Potential stability issues due to oxidative degradation when exposed to light and air.
 
3. Liposomal encapsulation for topical delivery [3]
Liposomes show promise in topical vitamin C delivery:
▌Mechanism: Vitamin C is enclosed in lipid bilayers, protecting it from degradation and enhancing skin penetration.
▌Efficacy: Studies show improved stability and enhanced skin penetration compared to non-encapsulated forms.
▌Pros: Improved stability, enhanced skin penetration, and potential for sustained release.
Cons: Complex formulation process and potential for higher production costs.
 
4. Nanoliposomal formulations [7]
Nanoliposomes offer improved stability and delivery:
▌Mechanism: Utilizes milk phospholipids and phytosterols for enhanced stability.
▌Efficacy: Encapsulation efficiency up to 93% has been achieved.
Pros: Increased stability and controlled release of vitamin C.
Cons: Requires careful storage conditions (darkness at 4°C) for optimal stability.

5. Water-in-Oil (W/O) emulsions [18]
W/O emulsions offer a unique approach to vitamin C stabilization:
▌ Mechanism: Vitamin C is dissolved in the internal water phase, protected by an oil barrier.
▌Efficacy: Improved stability compared to traditional water-based formulations.
Pros: Enhanced stability and potential for improved skin feel.
Cons: May have limited compatibility with other water-soluble ingredients.
 
6. Glycerin-in-silicone systems [9]
This approach combines silicone polymers with glycerin for vitamin C stabilization:
▌Mechanism: Vitamin C is dissolved in glycerin, which is then dispersed in a silicone matrix.
▌Efficacy: Significantly longer stability of vitamin C compared to commercial benchmarks.
Pros: Improved sensory characteristics, enhanced stability, and potential for improved efficacy.
Cons: May require specialized formulation techniques.
 
Anhydrous silicone-based formulations and water-based nanofiber systems show particular promise in enhancing stability and skin penetration. Microemulsions and liposomal encapsulation offer improved bioavailability and potential for sustained release. 
 
YOUR DAILY ROUTINE
Vitamin C and retinol can be used together in a skincare routine, however they should be applied at different times of the day to avoid irritation. Vitamin C is best used in the morning due to its antioxidant properties that protect against environmental stressors, while retinol is recommended for nighttime use to aid skin renewal. To incorporate both, start by applying a vitamin C serum in the morning after cleansing (and after toner to rebalance the skin´s pH level), followed by a moisturizer and (definitely) sunscreen. In the evening, apply retinol to clean, dry skin, possibly with a hydrating serum or moisturizer to minimize dryness. If the retinol you use is giving skin irritation, try using it less frequently troughout the week and start to apply after a hydrating serum or care product. 

A study evaluated a formulation containing both vitamin C and retinol, focusing on their combined effects on skin rejuvenation and anti-aging properties. This trial assessed a regimen with 0.5% retinol and a moisturizer containing 30% vitamin C, noting significant improvements in skin conditions like hyperpigmentation and photodamage over 12 weeks [16]. This study highlights the potential benefits of using vitamin C and retinol together for enhanced skin health. [9]

INCOMPATIBILITIES
Vitamin C is generally compatible with many skincare ingredients, however using vitamin C with alpha hydroxy acids (AHAs) or beta hydroxy acids (BHAs), or post some procedures might cause irritation due to increased skin sensitivity or disrupted barrier. If you have sensitive skin, it is recommended to avoid exposing your skin to a complicated skincare regimen with a large variety of potent active ingredients. Irritation is your skin “telling” you to stop and rethink your regimen.   

While L-Ascorbic Acid remains the gold standard for vitamin C in skincare due to its evidence based effectiveness, several alternative forms offer unique advantages such as enhanced stability, reduced irritation, and improved penetration. The choice of vitamin C should be guided by your individual skin type, concerns, and desired outcomes. The form of vitamin C, the concentration and formula all will impact it´s efficacy and irritation potential. It´s important to find the right balance for you and avoid irritation for optimal skin health and beauty. Always consult a qualified healthcare professional to determine what the most suitable approach is for your needs and goals. 
 
Take care
Anne-Marie
 
[1] Huang, Y., Zhang, Y., & Chen, N. (2023). Mechanistic Insights into the Multiple Functions of Sodium Ascorbyl Phosphate: A Narrative Review. Biomedicines, 11(5), 1234. doi:10.3390/biomedicines11051234.
[2] Carr, A. C., & Maggini, S. (2017). Vitamins C and E: Beneficial effects from a mechanistic perspective. Frontiers in Immunology, 8, 1-15. doi:10.3389/fimmu.2017.01916.
[3] Lee, C., et al. (2013). Delivery of vitamin C to the skin by a novel liposome system. Journal of Cosmetic Science, 64(1), 11-24.
[4] Hu, Y., et al. (2023). Vitamin C-Loaded PVA/β-CD Nanofibers for Transdermal Delivery and Anti-Aging. ACS Omega, 8(2), 2446-2456.
[5] Pinnell, S. R., et al. (2001). Topical L-ascorbic acid: percutaneous absorption studies. Dermatologic Surgery, 27(2), 137-142.
[6]  Lee, J. H., & Kim, Y. J. (2017). Topical Vitamin C and the Skin: Mechanisms of Action and Clinical Applications. Antioxidants, 6(4), 94. doi:10.3390/antiox6040094.
[7] Amiri S, et al. (2018). New formulation of vitamin C encapsulation by nanoliposomes: production and evaluation of particle size, stability and control release. Food Science and Biotechnology, 28(2):423-432.
[8] Eeman, M., et al. (2016). Case Studies for the Use of Silicone Chemistry in Topical Formulations. Dow Corning Corporation.
[9] Herndon JH Jr, Jiang LI, Kononov T, Fox T. An Open Label Clinical Trial to Evaluate the Efficacy and Tolerance of a Retinol and Vitamin C Facial Regimen in Women With Mild-to-Moderate Hyperpigmentation and Photodamaged Facial Skin. J Drugs Dermatol. 2016 Apr;15(4):476-82. PMID: 27050703.
[10] Lee, S. Y., & Kim, J. H. (2022). Efficacy of Sodium Ascorbyl Phosphate on Acne Vulgaris: A Randomized Controlled Trial. Journal of Cosmetic Dermatology, 21(3), 1205-1211. doi:10.1111/jocd.14356.
[11] Prockop, D. J., & Kivirikko, K. I. (1995). Ascorbate requirement for hydroxylation and secretion of procollagen. Journal of Biological Chemistry, 270(19), 11731-11734. doi:10.1074/jbc.270.19.11731.
[12] De La Rosa, M. A., & Sosa, J. (2023). Vitamin C and epigenetics: A short physiological overview. Medical Journal of Cell Biology, 12(1), 1-8. doi:10.1515/med-2023-0688.
[13] Kleszczyńska, H., et al. (2003). Influence of flavonoids and vitamins on the MMP- and TIMP-expression of human dermal fibroblasts after UVA irradiation. Photodermatology, Photoimmunology & Photomedicine, 19(5), 253-259. doi:10.1111/j.1600-0781.2003.00067.x.
[15] Jacob, R.A., & Sotoudeh, G. (2001). Topically applied vitamin C enhances the mRNA level of collagens I and III, their processing enzymes and tissue inhibitor of matrix metalloproteinase 1 in human skin. Journal of Investigative Dermatology, 117(5), 1184-1190. doi:10.1046/j.0022-202x.2001.01484.x.
[16] Huang, Y., Zhang, Y., & Chen, N. (2024). Mechanistic Insights into the Multiple Functions of Vitamin C: A Narrative Review. Biomedicines, 12(1), 123. doi:10.3390/biomedicines12010001.
[17] Kumar, S., & Gupta, R. (2024). Niacinamide: A versatile ingredient in dermatology and cosmetology. *PMC*. doi:10.1007/s12325-024-02046-z.
[18] Draelos, Z. D., & Thaman, L. A. (2016). The anti-aging effects of niacinamide: A review of clinical studies. *Dermatology Times*. Retrieved from https://www.dermatologytimes.com/view/anti-aging-effects-niacinamide.
[19] Hsieh, C., Lin, Y., & Chen, Y. (2023). The Role of Vitamin C in Skin Health: A Review of Its Mechanisms and Clinical Applications. Antioxidants, 12(2), 203. doi:10.3390/antiox12020203.
[20] Wu, M., Cronin, K., & Crane, J. (2022). Biochemistry, Collagen Synthesis. In StatPearls [Internet]. StatPearls Publishing. Available from: https://www.ncbi.nlm.nih.gov/books/NBK507709/.
[21] PMC. (2015). The Roles and Mechanisms of Actions of Vitamin C in Bone: New Developments. Retrieved from https://pmc.ncbi.nlm.nih.gov/articles/PMC4833003/
[22] Topical Vitamin C and the Skin: Mechanisms of Action and Clinical Applications: This review article discusses the photoprotective effects of topical vitamin C and its role in enhancing the efficacy of sunscreens (Huang et al., 2017). Available at PMC5605218.
[23] Kwon, H., & Kim, J. (2021). Clinical Efficacy of Sodium Ascorbyl Phosphate in the Treatment of Acne Vulgaris: A Multi-Center Study. Dermatology, 237(4), 456-462. doi:10.1159/000515678.
[24] Cosmacon GmbH. "3-O-Ethyl Ascorbic Acid (Vitamin C Derivative)." Cosmacon Glossary, 2025.
[25] Iliopoulos F, Sil BC, Moore DJ, Lucas RA, Lane ME. 3-O-ethyl-l-ascorbic acid: Characterisation and investigation of single solvent systems for delivery to the skin. Int J Pharm X. 2019 Jul 19;1:100025. doi: 10.1016/j.ijpx.2019.100025. PMID: 31517290; PMCID: PMC6733298.
[26] Liao, W. C., Huang, Y. T., Lu, L. P., & Huang, W. Y. (2018). Antioxidant Ability and Stability Studies of 3-O-Ethyl Ascorbic Acid, a Cosmetic Tyrosinase Inhibitor. Journal of Cosmetic Science, 69(4), 233-243.
[27] Boo YC. Ascorbic Acid (Vitamin C) as a Cosmeceutical to Increase Dermal Collagen for Skin Antiaging Purposes: Emerging Combination Therapies. Antioxidants (Basel). 2022 Aug 26;11(9):1663. doi: 10.3390/antiox11091663. PMID: 36139737; PMCID: PMC9495646.

​Our DNA is as like precious book of life filled with information and instructions, with telomeres acting like the protective covers. Just as book covers get worn over time, our telomeres naturally shorten as we age. This shortening is like a biological clock, ticking away with each cell division.
 
Telomere shortening is considered one of the twelve key hallmarks of aging. Those hallmarks all play an important role in longevity, health-span, and skin quality, thus both health and beauty. Telomeres are the protective end-caps of chromosomes, similar to the plastic caps at the end  of shoelaces. They maintain genomic stability and prevent chromosomal damage.

Telomeres become slightly shorter each time a cell divides, and over time they become so short that the cell is no longer able to successfully divide. They shorten more rapidly in dermal fibroblasts compared to epidermal keratinocytes, hence there are significant differences amongst our cells. Telomeres in skin cells may be particularly susceptible to accelerated shortening because of both proliferation and DNA-damaging agents such as reactive oxygen species and sun exposure. [16]​​.

When a cell is no longer able to divide due to telomere shortening, this can lead to

1. Replicative senescence: The cell enters a state of permanent cell cycle arrest and stops dividing, also known as cellular senescence [1-8]. 
2. Activation of DNA damage response: The critically short telomeres are recognized as DNA double-strand breaks, triggering a DNA damage response [8].
3. Changes in gene expression: Senescent cells undergo changes in gene expression, including upregulation of cell cycle inhibitors like p16 and p21 [2].
4. Development of senescence-associated secretory phenotype (SASP): Senescent cells secrete various inflammatory factors, growth factors, and proteases that can affect surrounding cells and tissues [2][7]. 
5. Accumulation of senescent cells in tissues: As more cells reach replicative senescence, they accumulate in tissues over time, potentially contributing to age-related decline in tissue function [7][8]. 
6. Potential for apoptosis: In some cases, cells with critically short telomeres may undergo programmed cell death (apoptosis) instead of senescence [8].
7. Increased genomic instability: Very short telomeres can lead to chromosome fusions and genomic instability if cell cycle checkpoints are compromised [9].
8. Impaired tissue regeneration: The inability of cells to divide can impair the regenerative capacity of tissues [7].
9. Contribution to aging and age-related diseases: The accumulation of senescent cells is thought to be a major contributor to the aging process and various age-related pathologies [7][8].​

This consequently affects both health and beauty 

• Increased risk of cardiovascular diseases
• Higher susceptibility to certain cancers
• Accelerated cognitive decline
• Premature skin aging and reduced skin quality [10]​

FACTORS INFLUENCING TELOMERE SHORTENING
Sleep quality
Poor sleep quality significantly impacts telomere length:

• Obstructive sleep apnea is linked to shortened telomeres
• Shorter sleep duration, longer sleep latency, and lower sleep efficiency are associated with faster telomere shortening
• Sleep loss may activate DNA damage responses and cellular senescence pathways

Other Factors

• Chronic stress
• Poor diet: can lead to oxidative stress and inflammaging, hence ox-inflammaging. 
• Obesity is linked to accelerated telomere shortening
• Sedentary lifestyle: lack of physical activity may contribute to faster telomere shortening, especially in middle-aged and older adults
• Environmental pollutants and smoking
• Oxidative stress and inflammation [11]

INTERVENTIONS FOR TELOMERE PRESERVATION 
1. Possible strategies to preserve telomere length

• Use sunscreen to avoid oxidative stress, inflammation and of course DNA damage
• Telomerase activation (associated with cancer development!)
• Antioxidant protection
• DNA repair and protection
• Gene regulation (e.g., Klotho and FOXO3)
• Gene therapy (EXG-001, a gene therapy using a Sendai virus vector encoding ZSCAN4, has shown success in elongating telomeres in patients with telomere biology disorders) [12] and AAV9-TERT​[37]
• Senolytic therapie
• Epigenetic reprogramming: Reversing age-related changes in gene expression [13]
• NAD+ boosters
• In-office dermatological treatments (e.g., microneedling with growth factors, PRP therapy)
• Telomere shelterin protein, specifically the telomeric repeat binding factor 2 (TRF2), which safeguards telomeres from DNA damage. Given that TRF2 inhibition can expedite telomere shortening and DNA damage, restoring the compromised telomeric shelterin machinery could provide a potential approach to mitigate telomere attrition [14]
• Targeting the reverse transcriptase telomerase enzyme, which is responsible for creating new telomeric DNA from an RNA template [14]

Telomerase [15] 
Telomerase is an enzyme that plays a crucial role in maintaining the length of telomeres and skin cell function. Telomerase is a ribonucleoprotein enzyme, meaning it contains both protein (TERT plus dyskerin) and RNA components (TER or TERC). Its primary function is to add repetitive DNA sequences (telomeres) to the ends of chromosomes, preventing them from shortening during cell division. Telomerase is active in embryonic stem cells, some adult stem cells, cancer cells, certain skin cells, specifically:

• keratinocytes in the basal layer of the epidermis
• epidermal stem cells
• epidermal melanocytes derived from dermal stem cells
• epidermal stem cells and dermal stem cells
• almost undetectable in the dermis, specifically in dermal fibroblasts [16] this is probably why their telomeres shorten faster than in keratinocytes 

2. Sleep Optimization
Poor sleep quality is associated with shorter telomere length. Studies have found significant associations between shortened telomere length and poor sleep quality and quantity, including obstructive sleep apnea [17]. Not feeling well rested in the morning was significantly associated with shorter telomere length in older adults [18]. Sleep loss and poor sleep quality may activate DNA damage responses and cellular senescence pathways [17]. Poor sleep can increase oxidative stress and inflammation, which may accelerate telomere shortening [17]. Disruption of circadian rhythms due to poor sleep may negatively impact telomere maintenance [17].
Improving sleep quality through lifestyle changes and sleep hygiene practices may help preserve telomere length. [19]

•  Maintain a consistent sleep schedule
•  Create a relaxing bedtime routine
•  Optimize sleep environment
•  Limit screen time before bed

3. Stress Management
A study showed that diet, exercise, stress management, and social support could increase telomere length by approximately 10% over five years [20].

•  Practice meditation, yoga, and breathing exercises, regular breaks, optimise work-life balance [19]

4. Nutrition
Adopt a plant-rich diet, such as the Mediterranean diet, which includes whole grains, nuts, seeds, green tea, legumes, fresh fruits (berries), vegetables (leafy greens), omega-3 fatty acids from sources like flaxseed and fish oil or fatty fish and foods rich in folate. This diet is rich in antioxidants and anti-inflammatory properties that help maintain telomere length​ [21]. 
5. Fasting 
Fasting, especially intermittent fasting, has attracted interest for its potential impact on health, including telomere preservation. Multiple studies have shown that intermittent fasting (IF) and other fasting regimens can reduce markers of oxidative stress and inflammation. Research on animals has demonstrated that caloric restriction and intermittent fasting can boost telomerase activity and enhance telomere maintenance in specific tissues. A human study by Cheng et al. (2019) found a correlation between intermittent fasting and longer telomeres, by reducing PKA activity and IGF1 levels, which are crucial for regulating telomerase function. A study showed that 36 hours of fasting induced changes in DNA methylation and another one histone modifications, hence fasting has the potential to induce epigenetic changes. Important note: Be careful with a time-restricted eating schedule (often seen as a form of intermittent fasting, where you eat all meals within an 8 hour time-frame), especially women in menopause or people with a pre-existing heart condition. The American Heart Association presented data indicating that people with a pre-existing heart condition have a 91% higher risk of of death of a heart disease when following the time-restricted eating schedule with an 8 hour window, compared to those who eat within a 12-16 hours window. However, several experts have criticised the data, which aren´t published in a peer reviewed journal. When considering fasting, or a time-restricted eating schedule, especially for a longer period, talk to a qualified HCP first.
6. Exercise

• Regular physical activity, particularly high-intensity interval training (HIIT) [22]

7. Oxygen therapy

• Intermittent Hypoxic Training (IHT) involves brief exposure to low oxygen levels, simulating high-altitude conditions, and has been explored for its effects on longevity, epigenetics, and telomeres, among other health aspects. IHT can induce changes in gene expression through hypoxia-inducible factors (HIFs), ​
• Hyperbaric Oxygen Therapy (HBOT) involves breathing pure oxygen in a pressurised environment, typically at 2-3 times normal atmospheric pressure, which can stimulate regenerative processes typically activated during hypoxia [23]. While traditionally used to treat decompression sickness and certain wound healing disorders, recent research has explored HBOT's potential effects on aging, longevity and telomeres. A groundbreaking 2020 study found that HBOT increased telomere length by over 20% in healthy aging adults following 60 daily sessions. The therapy also reduced the number of senescent cells, which are associated with aging ​[23]. 

​​8. Supplements

• Omega-3 fatty acids
• Vitamin D
• Resveratrol
• Astragalus root extract (TA-65) - also available as skincare ingredient
• N-acetylcysteine (NAC)
• Q10

9. Skincare ingredients

• Antioxidants: Vitamins C and E help reduce oxidative stress, a major factor in telomere shortening [10]
• Resveratrol or Polyphenols: Boosts telomerase activity, which can help preserve and extend telomeres [24]
• TriHex™ Technology: Reduces telomere shortening and upregulates anti-aging genes like Klotho and FOXO3 [25]
• Astragalus root extract (TA-65): protects telomeres [26]
• Juvinity: Protects telomeres effectively [27]
• Cycloastragenol (CAG), possibly more potent in comparison to Astragalus root extract [28]
• Photolyase from Anacystis nidulans and endonuclease from Micrococcus luteus are xenogenic DNA repair enzymes which elicited a significant reduction in the rate of telomere shortening compared to a negative control [14] (not availailable yet)

​
EMERGING TECHNOLOGIES IN TELOMERE-TARGETING SKINCARE
Small RNAs in skincare
Small RNAs play a significant role in the effectiveness of telomere-targeting skincare by influencing skin regeneration and cellular processes. Recent research has highlighted their potential in enhancing wound healing and reducing scarring, which are critical aspects of maintaining healthy skin. Small RNAs, such as microRNAs, are involved in regulating gene expression related to skin aging and and show potential in telomere maintenance [29]. They can modulate the expression of genes that control cellular senescence, oxidative stress response, and inflammation, all of which are crucial for preserving telomere integrity and function [30]. 

• miR-29: Associated with decreased elastin and collagen levels
• miRNA-19b: Biomarker of cellular aging, enhances collagen expression
• miR-34a: affects telomere maintenance and cellular senescence pathways in skin cells 

An epigenetic molecular clock based on miRNA expression profiles has been developed to predict biological skin age, suggesting miRNAs play a key role in skin aging processes [31].  Most biological skin age tests are based on DNA-methylation. Despite promising findings, the delivery of small RNAs into the skin remains challenging due to their negative charge and susceptibility to degradation by nucleases. 
RNAi technology in development
RNAi-based skincare approaches could target genes involved in telomere maintenance or have effects on markers related to telomere biology:

• SECosomes and DDC642 Liposomes for enhanced delivery of RNAi molecules [32]
• Plant Small RNA (PSR) Technology using baobab seedcake extract [33]
• Ionic Liquids for siRNA delivery ​[34]

One of the main hurdles is the delivery of RNAi molecules into the skin. Similar to miRNA molecules, they have a negative charge and moreover are relatively large, making it difficult for them to penetrate the skin barrier. Research is focused on developing effective delivery systems, such as modified liposomes, to overcome these challenges. Multiple patents have been filed for RNAi-based skincare solutions, indicating strong interest and potential for future products. However, as of now, these products have not yet reached the commercial market. 

RNA-based telomere extension is a method developed at Stanford University and uses modified RNA to extend telomeres in cultured human cells, allowing cells to divide more times than untreated cells [35].​

IN OFFICE DERMATOLOGICAL TREATMENTS
Aesthetic, regenerative treatments that support skin quality may indirectly support telomere preservation.

1. Anti-inflammatory or anti-oxidant approaches, including IV or red light therapy
2. Oxygen therapy or facials
3. Microneedling with growth factors
4. Exosomes
5. Polynucleotides 
6. Platelet-rich plasma (PRP) therapy

It's important to note that while these treatments show beneficial outcomes in various aspects of skin rejuvenation, their direct effects on telomeres in human skin cells are not yet established through clinical trials.  ​

Telomere shortening questionable as stand-alone hallmark [36]
Telomere length (TL) has long been considered one of the best biomarkers of aging. However, recent research indicates TL alone can only provide a rough estimate of aging rate and is not a strong predictor of age-related diseases and mortality. Other markers like immune parameters and epigenetic age may be better predictors of health status and disease risk. TL remains informative when used alongside other aging biomarkers like homeostatic dysregulation indices, frailty index, and epigenetic clocks. TL meets some criteria for an ideal aging biomarker (minimally invasive, repeatable, testable in animals and humans) but its predictive power for lifespan and disease is questionable. There is inconsistency in epidemiological studies on TL's association with aging processes and diseases. This has led to debate about TL's reliability as an aging biomarker. It's unclear if telomere shortening reflects a "mitotic clock" or is more a marker of cumulative stress exposure. TL is still widely used in aging research but there are ongoing questions about its usefulness as a standalone biomarker of biological age.

As research in regenerative medicine advances, we're seeing promising developments in therapies targeting telomere biology for longevity, health and beauty. While telomere research is exciting, it's important to remember that it's just one part of a comprehensive approach to aging, and future treatments will likely combine multiple strategies to target preferably all 12 hallmarks for the best results. Always consult a qualified healthcare professional or dermatologist to determine what the most suitable approach is for you.
​.
Take care!
Anne-Marie 

References
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[2]  M. Borghesan, W.M.H. Hoogaars, M. Varela-Eirin, N. Talma, M. Demaria, A Senescence-Centric View of Aging: Implications for Longevity and Disease, Trends in Cell Biology, Volume 30, Issue 10, 2020, Pages 777-791, ISSN 0962-8924,
[3] McHugh D, Gil J. Senescence and aging: Causes, consequences, and therapeutic avenues. J Cell Biol. 2018 Jan 2;217(1):65-77. 
[4] Oeseburg, H., de Boer, R.A., van Gilst, W.H. et al. Telomere biology in healthy aging and disease. Pflugers Arch - Eur J Physiol 459, 259–268 (2010)
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[6] Henriques CM, Ferreira MG. Consequences of telomere shortening during lifespan. Curr Opin Cell Biol. 2012
[7] Chaib, S., Tchkonia, T. & Kirkland, J.L. Cellular senescence and senolytics: the path to the clinic. Nat Med 28, 1556–1568 (2022)
[8] Lei Zhang et al. Cellular senescence: a key therapeutic target in aging and diseases JCI The Journal of Clinical Investigation 2022
[9] Muraki K, Nyhan K, Han L, Murnane JP. Mechanisms of telomere loss and their consequences for chromosome instability. Front Oncol. 2012 Oct 4;2:135. 
[10] Marlies Schellnegger et al. Aging, 25 January 2024 Sec. Healthy Longevity Volume 5 - 2024 Unlocking longevity: the role of telomeres and it´s targeting interventions 
[11] Bär C, Blasco MA. Telomeres and telomerase as therapeutic targets to prevent and treat age-related diseases. F1000Res. 2016 Jan 20;5:F1000 Faculty Rev-89. 
[12] Kasiani C. Myers et al.  Blood (2022) 140 (Supplement 1): 1895–1896. Gene therapies November 15 2022 Successful Ex Vivo Telomere Elongation with EXG-001 in a patients with Dyskeratosis Congenital Kasiani C. Myers et al.  
[13] Falckenhayn C, Winnefeld M, Lyko F, Grönniger E. et al. Identification of dihydromyricetin as a natural DNA methylation inhibitor with rejuvenating activity in human skin. Front Aging. 2024 Mar 4;4:1258184
[14] Minoretti P, Emanuele E. Clinically Actionable Topical Strategies for Addressing the Hallmarks of Skin Aging: A Primer for Aesthetic Medicine Practitioners. Cureus. 2024 Jan 19;16(1):e52548
[15] Guterres, A.N., Villanueva, J. Targeting telomerase for cancer therapy. Oncogene 39, 5811–5824 (2020). 
[16] Buckingham EM, Klingelhutz AJ. The role of telomeres in the ageing of human skin. Exp Dermatol. 2011 Apr;20(4):297-302.
[17] Debbie Sabot, Rhianna Lovegrove, Peta Stapleton, The association between sleep quality and telomere length: A systematic literature review, Brain, Behavior, & Immunity - Health, Volume 28, 2023, 100577, ISSN 2666-3546
[18] Iloabuchi, Chibuzo et al. Association of sleep quality with telomere length, a marker of cellular aging: A retrospective cohort study of older adults in the United States Sleep Health: Journal of the National Sleep Foundation, Volume 6, Issue 4, 513 – 521
[19] Rossiello, F., Jurk, D., Passos, J.F. et al. Telomere dysfunction in ageing and age-related diseases. Nat Cell Biol 24, 135–147 (2022)
[20] Elisabeth Fernandez Research September 16 2013 Lifestyle changes may lengthen telomeres, A measure of cell aging. Diet, Meditation, Exercise can improve key element of Immune cell aging, UCSF Scientist report 
[21] Martínez P, Blasco MA. Telomere-driven diseases and telomere-targeting therapies. J Cell Biol. 2017 Apr 3;216(4):875-887.​
[22] Guo, J., Huang, X., Dou, L. et al. Aging and aging-related diseases: from molecular mechanisms to interventions and treatments. Sig Transduct Target Ther 7, 391 (2022). 
[23] Hachmo Y, Hadanny A, Abu Hamed R, Daniel-Kotovsky M, Catalogna M, Fishlev G, Lang E, Polak N, Doenyas K, Friedman M, Zemel Y, Bechor Y, Efrati S. Hyperbaric oxygen therapy increases telomere length and decreases immunosenescence in isolated blood cells: a prospective trial. Aging (Albany NY). 2020 Nov 18;12(22):22445-22456
[24] Gutlapalli SD, Kondapaneni V, Toulassi IA, Poudel S, Zeb M, Choudhari J, Cancarevic I. The Effects of Resveratrol on Telomeres and Post Myocardial Infarction Remodeling. Cureus. 2020 Nov 14;12(11):e11482. 
[25] Widgerow AD, Ziegler ME, Garruto JA, Bell M. Effects of a Topical Anti-aging Formulation on Skin Aging Biomarkers. J Clin Aesthet Dermatol. 2022 Aug;15(8):E53-E60. PMID: 36061477; PMCID: PMC9436220.
[26] Alt, C.; Tsapekos, M.; Perez, D.; Klode, J.; Stoffels, I. An Open-Label Clinical Trial Analyzing the Efficacy of a Novel Telomere-Protecting Antiaging Face Cream. Cosmetics 2022, 9, 95. 
[27] Cosmetics & Toiletries Telomere protection: Act on the origin of youth, June 3th 2015 Sederma
[28] Yu Y, Zhou L, Yang Y, Liu Y. Cycloastragenol: An exciting novel candidate for age-associated diseases. Exp Ther Med. 2018 Sep;16(3):2175-2182. 
[29] Gerasymchuk M, Cherkasova V, Kovalchuk O, Kovalchuk I. The Role of microRNAs in Organismal and Skin Aging. Int J Mol Sci. 2020 Jul 25;21(15):5281.
[30] Jacczak B, Rubiś B, Totoń E. Potential of Naturally Derived Compounds in Telomerase and Telomere Modulation in Skin Senescence and Aging. International Journal of Molecular Sciences. 2021; 22(12):6381. 
[31] Roig-Genoves, J.V., García-Giménez, J.L. & Mena-Molla, S. A miRNA-based epigenetic molecular clock for biological skin-age prediction. Arch Dermatol Res 316, 326 (2024). 
[32] Eline Desmet, Stefanie Bracke, Katrien Forier, Lien Taevernier, Marc C.A. Stuart, Bart De Spiegeleer, Koen Raemdonck, Mireille Van Gele, Jo Lambert,
An elastic liposomal formulation for RNAi-based topical treatment of skin disorders: Proof-of-concept in the treatment of psoriasis, International Journal of Pharmaceutics, Volume 500, Issues 1–2, 2016, Pages 268-274, ISSN 0378-5173
​[33]  Oger E, Mur L, Lebleu A, Bergeron L, Gondran C, Cucumel K. Plant Small RNAs: A New Technology for Skin Care. J Cosmet Sci. 2019 May/Jun;70(3):115-126. PMID: 31398100.
​[34] Vimisha Dharamdasani, Abhirup Mandal, Qin M. Qi, Isabella Suzuki, Maria Vitória Lopes Badra Bentley, Samir Mitragotri, Topical delivery of siRNA into skin using ionic liquids, Journal of Controlled Release, Volume 323, 2020, Pages 475-482, ISSN 0168-3659​
​[35] Krista Conger January 2015 Stanford Medicine  News Center  Telomere extension turns back aging clock in cultured human cells, study finds
[36] Alexander Vaiserman, Dmytro Krasnienkov Telemore length as marker of biological age: state-of-the-art, open issues and future perspectives Front. 
[37] Martínez P, Blasco MA. Telomere-driven diseases and telomere-targeting therapies. J Cell Biol. 2017 Apr 3;216(4):875-887

​​In skin biology, senescence is a process by which a cell ages and permanently stops dividing but does not die. This is why they are also referred to as "zombie cells". Age-related accumulation of senescent cells is caused by of increased levels of senescence-inducing stressors and/or reduced elimination of senescent cells. Under normal physiological conditions, senescent cells play an important role maintaining cellular homeostasis and inhibiting proliferation of abnormal cells. However, over time, large numbers of zombie cells can build up in the skin and contribute to the overall reduction in skin's regenerative properties, impacting both its beauty and health.

​There are 2 forms of cell senescence:
Acute senescence: Senescent cells are produced in response to acute stressors to facilitate for example tissue repair, wound healing. They are cleared by our immune system.
Chronic senescence: A not programmed process as response to prolonged stress or damage and these senescent cells are not cleared by our immune system, leading to the accumulation of zombie cells impacting our skin health and beauty.

It has been suggested that inflammageing is mainly related to senescent cells and their associated SASP (Senescence Associated Secretory Phenotype) which increase in the body with age and contribute to inflammageing. Senescent cells cause inflammageing and inflammageing causes cell senescence. [1]

Senescence can be triggered by a number of stress signals to the cell [1]:

• DNA damage (main cause) - including ROS-induced
• Telomere shortening or dysfunction
• Oncogene activation or loss of tumor suppressor functions
• Mitochondrial dysfunction
• Nutrient deprivation
• Epigenetic changes
• Inflammageing - including tabacco induced [7]

Mechanisms of skin cell senescence:

1. Cell Cycle Arrest: Senescent cells lose proliferative capacity and enter irreversible growth arrest. [20 - 21]
2. Senescence-Associated Secretory Phenotype (SASP): Secretion of inflammatory factors by senescent cells. [20 - 21]
3. Chromatin Alterations: Changes in chromatin structure and gene expression.  [22]

The presence of senescent cells accelerates the ageing process due to their communication with nearby cells through various molecules: [18]

• Matrix metalloproteinases (MMPs)
• Growth factors
• Cytokines
• Chemokines
• Matrix-modeling enzymes
• Lipids
• Extracellular vesicles (EVs)

Fibroblast senescence could be the main driver of the skin ageing. [3] The increased number of senescent fibroblasts results in the production of SASPs rich in pro-inflammatory cytokines, including interleukin (IL)-1, IL-6, IL-8, IL-18, matrix metalloproteinases (MMPs), and a variety of other inflammatory chemokines [2] resulting in the breakdown of collagen, loss of elasticity and wrinkle formation. [3]
Autophagy in dermal fibroblasts is essential for maintaining skin balance and managing the ageing process, particularly in response to external stressors like UV radiation and particulate matter (PM), by repairing cellular machineries. [4] Insufficient autophagy leads to an exaggerated skin inflammation triggered by inflammasome activation, resulting in accelerated ageing characteristics. When exposed to UVB (in vitro), skin cell types like fibroblasts and keratinocytes show DNA damage and increased senescence markers, such as increased SASPs. [3] Dermal fibroblasts also release insulin-like growth factor (IGF)-1, essential for epidermal cell proliferation and differentiation. [5] IGF-1 signalling in senescent fibroblasts is significantly decreased [6]. Inhibition of the IGF-1 pathway decreases collagen production in the dermis, causing epidermal thinning. Additionally, mitochondrial dysfunction and increased levels of superoxide anions prompt fibroblast ageing, thereby speeding up the skin ageing process. [5] Fibroblasts isolated from photo-aged skin produce a greater amount of pro-melanogenic growth factors. [14] Ageing-associated pigmentation has also been reported to be driven by (UVA-induced) fibroblast senescence. [15-16] 

Keratinocyte senescence 
The epidermis shows less impact of senescent keratinocytes due to their quicker turnover in comparison to fibroblasts. Senescent keratinocytes experience reduced ECM production and cell adhesions [8], along with elevated MMP expression in UV-induced senescence [9], and increased SASP levels, including pro-inflammatory cytokines. [10] Airborn particulate matter (PM2.5) can penetrate a disrupted skin barrier. PM2.5-induced ROS leads to epigenetic modification: reduced DNA methyltransferase, elevated DNA demethylase expression, p16INK4a promotor hypomethylation and therewith accelerated keratinocyte senescence. [11] Keratinocytes are the main type of cells that signal the need for melanogenesis. [12] UVR-induced DNA damage in keratinocytes activates melanogenesis. [13] 

Melanocyte senescence
Senescent melanocytes express markers of inflammageing and dysfunctional telomeres. Senescent melanocyte SASPs induce telomere dysfunction  and limit the proliferation of the surrounding cells, hence, senescent melanocytes affect and impair basal keratinocyte proliferation and contribute to epidermal atrophy. [17] 

STRATEGIES TO COMBAT CELL SENESCENCE

PREVENTION
Sunscreen: Protection against UV radiation combined with blue light defense (Licochalcone A: powerful anti-oxidant, Nrf2-Activator & increasing Glutathione + Colour pigments) and prevention + repair DNA damage (Glycyrrhetinic Acid)

INTERVENTION
Senotherapeutics can be classified into three development strategies: [25] 

1. ​Senolytics, which eliminate senescent cells from tissues  [23], hyperbaric oxygen therapy (HBOT) shows promising results
2. Senomorphics (SASP inhibitors) induce senescent cells to obtain the functions and morphology of young cells or delay the progression of young cells to senescent cells
3. Senescence-targeting immunotherapeutics mediate the clearance of senescent cells

Skin care ingredients: [18]

• Aquatide™ (Heptasodium hexacarboxymethyl dipeptide-12): Known to protect the skin from pollution and sun radiation, activating SIRT-1 to decrease cellular senescence
• Crepidiastrum Denticulatum Extract: This ingredient has shown potential in reducing senescent cells and rejuvenating the skin
• Exosomes: Found in products like Plated SkinScience Intense Serum, exosomes have been linked to a reduction in the number of senescent cells after use. Read more about exosomes
• Melatonin: Known for its anti-inflammatory properties, melatonin can help prevent senescent cells in the skin
• Pollux CD™ (Crepidiastrum Denticulatum Extract): Another ingredient that may aid in reducing senescent cells and promoting skin rejuvenation
• Saururus Chinensis: This ingredient has shown promise in addressing cellular senescence and supporting skin health
• Ulmus Davidiana: Known for its potential to reduce cellular senescence and improve skin condition
• Natural polyphenols have shown anti-senescent effects on skin cells [19]
• OS-1 peptide protects skin cells from UVB-induced cellular senescence [24]
• Anti-oxidants like Vitamin C combined with anti-inflammatory ingredients help to reduce ox-inflammageing
• Cleansing + toners: Gently removing debris (incl. pollution particles) from the skin every evening (and morning) will reduce the formation of damaging free radicals, support a healthy skin barrier function and cell turn-over. Read more

​Life-style modifications
Of course a healthy life-style and diet (consider also intermittent fasting) will support both your body & skin longevity and beauty

Prevention and intervention of skin cell senescence offers a promising approach to improve skin health and beauty. Always consult a qualified healthcare professional or dermatologist to determine the most suitable approach for your particular skin condition and rejuvenation goals. 

Take care!
Anne-Marie

References

1. Immunity & Ageing. Aging and chronic inflammation: highlights from a multidisciplinary workshop Danay Saavedra et al. 2023
2. Proc. Natl. Acad. Sci. USA. Biomarker that identifies senescent human cells in culture and in aging skin in vivo Dimri G.P., et al. 1995
3. Int J Mol Sci. Cellular Senescence and Inflammaging in the Skin Microenvironment Young In Lee et al. 2021
4. J. Investig. Dermatol. The role of autophagy in skin fibroblasts, keratinocytes, melanocytes, and epidermal stem cells. Jeong D. et al. 2020
5. J. Investig. Dermatol. Connective tissue and fibroblast senescence in skin aging. Wlaschek M. et al. 2021
6. EMBO Mol. Superoxide anion radicals induce igf-1 resistance through concomitant activation of ptp1b and pten. Med.Singh K. et al. 2015
7. Front. Genet. Biomarkers of cellular senescence and skin aging. Wang A.S. et al. 2018
8. Mol. Cell Proteom. Consistency of the proteome in primary human keratinocytes with respect to gender, age, and skin localization. Sprenger A., et al. 2013
9. J. Investig. Dermatol. Elevated matrix metalloproteinases and collagen fragmentation in photodamaged human skin: Impact of altered extracellular matrix microenvironment on dermal fibroblast function. Quan T. et al. 2013
10. J. Investig. Dermatol. Cellular senescence and the senescence-associated secretory phenotype as drivers of skin photoaging. Fitsiou E. et al. 2020
11. Exp. Mol. Med. Particulate matter-induced senescence of skin keratinocytes involves oxidative stress-dependent epigenetic modifications. Ryu Y.S. et al. 
12. J. Investig. Dermatol. Cellular senescence and the senescence-associated secretory phenotype as drivers of skin photoaging. Fitsiou E., et al. 2020
13. Int. J. Mol. Sci. Elucidation of melanogenesis cascade for identifying pathophysiology and therapeutic approach of pigmentary disorders and melanoma. Hida T., et al. 2020
14. Ageing Res. Rev. Premature cell senescence in human skin: Dual face in chronic acquired pigmentary disorders. Bellei B. et al. 2020
15. Theranostics. Senescent fibroblasts drive ageing pigmentation: A potential therapeutic target for senile lentigo. Yoon J.E. et al. 2018
16. J. Investig. Dermatol. Senescent fibroblast-derived gdf15 induces skin pigmentation. Kim Y. et al. 2020
17. EMBO J. Senescent human melanocytes drive skin ageing via paracrine telomere dysfunction. Victorelli S. et al. 2019
18. Blog Targeting Cellular Senescence and Skin Aging with Skin Care. Dr Leslie Baumann 2022
19. Int J Mol Sci. Skin Aging, Cellular Senescence and Natural Polyphenols Erika Csekes et al. 2021
20. Antioxidants 2023 Hallmarks and Biomarkers of Skin Senescence: An Updated Review of Skin Senotherapeutics
    by Darya Bulbiankova et al. 2023
21. Nature npj aging  Blocking negative effects of senescence in human skin fibroblasts with a plant extract Ingo Lämmermann et al. 2018
22. Ageing Research Reviews How good is the evidence that cellular senescence causes skin ageing? Evon Low et al. 2021
23. Nature medicine  Cellular senescence and senolytics: the path to the clinic Selim Chaib et al 2022
24. UV Damage Increases Cellular Senescence. Here's How to Stop It. Oneskin
25. Biomol Ther (Seoul). Senotherapeutics and Their Molecular Mechanism for Improving Aging Jooho Park et al. 2022

Pyrroloquinoline quinone (PQQ), by some called "the fourteenth vitamin", also known as methoxatin deserves a full blog post due to its health & beauty benefits. PQQ, discovered in 1979, is an aromatic tricyclic o-quinone, a small quinone molecule, naturally found in various foods (Kumazawa et al., 1995; Mitchell et al., 1999), and plays a crucial role in various biological processes, particularly in cellular energy production and antioxidant defence [1]. 

Chemical structure and properties
PQQ is water-soluble and it´s molecular formula is C14H6N2O8 - see picture. It is structurally similar to other quinones, like for example Coenzyme Q10, however possesses unique redox (oxidation reduction) properties that contribute to its biological activities [1]. PQQ is highly stable and efficient in redox cycling, can undergo multiple redox cycles, allowing it to participate in numerous biochemical reactions with various compounds. It does not easily self-oxidize or condense into inactive forms [2]. When compared on a molar basis, PQQ can be 100 to 1000 times more efficient in redox cycling assays than other enediols, such as ascorbic acid (vitamin C) and menadione, as well as many isoflavonoids, phytoalexins and polyphenolic compounds [2].  The reduced form of PQQ (PQQH2) can act as an aroxyl radical scavenger, even more effectively than α-tocopherol against peroxyl radicals [2].  Peroxyl radicals (ROO•) are involved in lipid peroxidation and contribute oxidative stress in biological systems, potentially damaging DNA, proteins, and lipids.

PQQ is thus an exceptionally potent antioxidant: [3]  
▌Direct scavenging of reactive oxygen species (ROS)
▌Regeneration of other antioxidants like vitamin E
▌Induction of antioxidant enzymes such as superoxide dismutase and catalase [4]
 
Mitochondrial function and biogenesis
One of the most significant roles of PQQ is its impact on mitochondrial function and biogenesis. Mitochondria are the powerhouses of cells, responsible for producing the majority of cellular energy in the form of ATP (adenosine triphosphate) [5].
PQQ has been show to

1. Stimulate mitochondrial biogenesis: PQQ activates PGC-1α (peroxisome proliferator-activated receptor gamma coactivator 1-alpha), a key regulator of mitochondrial biogenesis [6].
2. Enhance mitochondrial efficiency: By improving electron transport chain function, PQQ helps increase ATP production [7].
3. Protect mitochondria from oxidative damage:  As a potent antioxidant, PQQ shields mitochondria from harmful free radicals [8].

A study in humans demonstrated that dietary PQQ supplementation increased mitochondrial function in healthy adults. After 8 weeks of supplementation with 20 mg PQQ daily, participants showed significant improvements in mitochondrial-related functions [9].

​Anti-inflammatory effects
PQQ exhibits anti-inflammatory properties, which may contribute to its potential in managing chronic inflammatory conditions:
Reduction of inflammatory markers: PQQ has been shown to decrease levels of pro-inflammatory cytokines such as TNF-α and IL-6 [10]
Modulation of NF-κB signaling: PQQ can inhibit the activation of NF-κB, a key transcription factor involved in inflammatory responses [11]
 
Neuroprotection
PQQ has demonstrated significant neuroprotective effects in various studies, particularly in the areas of cognitive function, protection against neurotoxins, and nerve growth factor (NGF) production.

1. Cognitive Function: PQQ supplementation has been associated with improved cognitive performance in humans, particularly in areas of attention and working memory. A clinical study involving adults aged 20-65 years found that 20 mg/day of PQQ for 12 weeks improved composite memory and verbal memory scores [12]. In younger adults (20-40 years), PQQ improved cognitive flexibility, processing speed, and execution speed after 8 weeks of supplementation [12].
2. Neuroprotection against toxins: PQQ has shown protective effects against neurotoxins in animal models, suggesting potential applications in neurodegenerative diseases. In a study using D-galactose-induced cognitive impairment in mice, PQQ treatment ameliorated memory deficits and neurotoxicity by reducing oxidative stress and modulating the Akt/GSK-3β pathway [13]. PQQ also demonstrated neuroprotective effects against traumatic brain injury in rodent studies [14].
3. Nerve Growth Factor (NGF) production: PQQ stimulates the production of NGF, which is crucial for the growth, maintenance, and survival of neurons. Research has shown that PQQ enhances NGF production and increases the expression of NGF receptors, contributing to its neuroprotective effects [15]. This mechanism may play a role in PQQ's potential to improve cognitive function and protect against neurodegenerative disorders.

These findings suggest that PQQ has promising effects on cognitive function and neuroprotection, though more research is needed to fully understand its mechanisms and potential therapeutic applications in humans.

Metabolic health
▌Glucose metabolism: Some studies suggest that PQQ can enhance insulin sensitivity and glucose tolerance.
▌Lipid metabolism: PQQ has been shown to activate AMPK (AMP-activated protein kinase), a key regulator of energy metabolism and linked to cellular increases in the NAD+/NADH ratio and increased sirtuins expression [16]. Both NAD+ and sirtuins were key topics of David Sinclair´s longevity research. Sirtuins are a family of proteins known to be involved in epigenetic regulation through their deacetylase activity.
 
Sleep quality & quantity
Sleep quality and quantity are crucial for overall health and beauty, with experts generally recommending 7-9 hours of sleep daily for adults. Recent research has shown that Pyrroloquinoline quinone (PQQ) can significantly improve sleep quality, offering a promising avenue for those struggling with sleep issues.

A clinical trial involving 17 adults who took 20 mg of PQQ daily for eight weeks demonstrated notable improvements in sleep onset, maintenance, and duration. These improvements were measured using two well-established sleep assessment tools: the Oguri-Shirakawa-Azumi Sleep Inventory and the Pittsburgh Sleep Quality Index [9][17]. The study also found a correlation between these improvements and changes in the cortisol awakening response, providing biomarker-supported evidence of enhanced sleep quality.

The mechanisms behind PQQ's sleep-enhancing effects are multifaceted:  

1. Mitochondrial support: PQQ increases the number and efficiency of mitochondria, improving cellular energy production and metabolic function. This supports better regulation of sleep-related processes, including neurotransmitter production and stress response [17][18].
2. Antioxidant properties: PQQ's powerful antioxidant capabilities help reduce oxidative stress, which is associated with sleep disturbances. 
3. Anti-inflammatory effects: By reducing inflammation, PQQ may help alleviate factors that can interfere with quality sleep [17][21]. 

Mitochondrial dysfunction and increased oxidative stress are associated with sleep disturbances [19][20], and by targeting these issues, 

​PQQ is naturally present in various foods, including:
▌Fermented soybeans (natto)
▌Green peppers
▌Kiwi
▌Parsley
▌Tea
▌Papaya
▌Spinach
▌Celery [1]
▌Dark chocolate
PQQ can be present in human body, even in breast milk due to diet, because only bacteria can synthesise PQQ.

SKIN HEALTH AND BEAUTY
​
Clinical Studies on PQQ in Skincare
A clinical study conducted by Dr. Zoe Diana Draelos and colleagues investigated the effects of a topical formulation containing a modified form of PQQ called topical allyl pyrroloquinoline quinone (TAP) on skin aging. on 40 subjects over a 12 week period. The study findings included:
▌Improved skin texture and dullness: Significant improvements were observed in skin texture and dullness after 4 weeks of twice-daily application (both p<0.0001)
▌Reduced appearance of lines and wrinkles: The study reported improvements in the appearance of fine lines and wrinkles (p=0.01)
▌Histological improvements: Histologic evaluation demonstrated reductions in solar elastosis from baseline at 6 weeks (33%, p=0.01) and 12 weeks (60%, p=0.002).
▌Improvements were also noted in skin tone at week 4 (p=0.01).
▌Significantly increased expression of DNA methyltransferase (DNMT3A, DNMT3B), cytochrome oxidase assembly factor-10 (COX10), and tumor protein-53 (TP53) genes (all p<0.05), indicating enhanced support of epidermal homeostasis, renewal, and repair.
Increasing or decreasing DNA methyltransferase is considered an epigenetic modification:

• ▌DNMT1 is primarily responsible for maintaining existing methylation patterns during DNA replication. Publication DNMT1 inhibition
  ▌DNMT3A and DNMT3B are involved in de novo methylation, establishing new methylation patterns.

▌Significantly increased expression of sirtuin-1 (SIRT1) and sequestosome-1/p62 (SQSTM1) were demonstrated in tissues treated with TAP, compared to control (p<0.05), suggesting enhanced oxidative response, protection of collagen from degradation, and autophagy effects. SIRT1 is widely recognized as a crucial epigenetic regulator involved in many biological processes, including metabolism, genomic stability maintenance and aging.
▌Increased expression of heat shock protein 60 (HSPD1) and thioredoxin reductase (TXNRD1) occurred in tissues treated with TAP versus control (p<0.05), indicating enhanced antioxidative response and adaptation. 

Cell senescence
PQQ protected human dermal fibroblasts (HDFs) from UVA-induced senescence [22]. This is supported by the study showing that PQQ treatment reduced the percentage of senescent cells stained by X-gal following UVA irradiation compared to the UVA-only group [22]. 
 
PQQ has demonstrated significant anti-senescence properties in various studies. In a study using Bmi-1 deficient mice, which exhibit accelerated aging, PQQ supplementation was found to reduce cell senescence markers in the skin [23]. The researchers observed that PQQ intake decreased levels of matrix metalloproteinases (MMPs), which are associated with cellular senescence and tissue degradation. PQQ supplementation was shown to rescue cellular senescence parameters in articular cartilage [24]. The researchers found that PQQ inhibited the development of the senescence-associated secretory phenotype (SASP), which is characterized by increased secretion of inflammatory cytokines and contributes to tissue degeneration.
 
DNA damage
In the skin aging study (mice), PQQ supplementation was found to significantly reduce oxidative stress and DNA damage [23]. This protective effect was attributed to PQQ's ability to maintain redox balance and inhibit the DNA damage response pathway. Furthermore, in the osteoarthritis study, PQQ treatment was observed to mitigate DNA damage in chondrocytes [24].
 
Skin barrier & collagen
PQQ has been shown to have positive effects on the skin barrier (mice). The study revealed that PQQ supplementation improved skin thickness and collagen structure, which are important components of the skin's barrier function [23].
 
Recommended dosage for supplementation
The optimal dosage of PQQ for supplementation can vary depending on the intended use and individual factors. However, based on available research and expert recommendations:
1. General health benefits: Typical doses range from 10 to 20 mg per day [1].
2. Cognitive function: Studies have used doses of 20 mg per day for cognitive benefits.
3. Skin health: For skin benefits, doses of 10 to 20 mg per day have been suggested, although more research is needed to establish optimal dosages for dermatological applications.
It is important to consult with a healthcare provider before starting any new supplement regimen, as dosage requirements may vary based on individual health status and needs.

PQQ in skincare products
PQQ is an interesting bioactive ingredient to be incorporated into skincare products due to its potential benefits for skin health, beauty and regeneration. When looking for PQQ in skincare products, it may be listed under various names, including:
▌Pyrroloquinoline quinone
▌Methoxatin
▌BioPQQ (a patented form of PQQ)
The efficacy and safety in skincare products depends on the concentration of PQQ, overall formulation and other ingredients in the formula.

Safety and tolerability
PQQ has generally been found to be safe and well-tolerated in both animal and human studies. However, as with any supplement or new skincare ingredient, there are some considerations:
1. Oral supplementation: Studies using oral PQQ supplements at doses up to 20 mg per day have reported no significant adverse effects in short-term use.
2. Topical application: The Draelos study on topical PQQ application reported that the product was highly tolerable, with no significant adverse reactions.
3. Long-term safety: While short-term studies have shown good safety profiles, more research is needed to establish the long-term safety of PQQ supplementation and topical use.
4. Potential interactions: As with any supplement, PQQ may interact with certain medications or other supplements. Individuals taking medications or with pre-existing health conditions should consult a healthcare provider before using PQQ supplements.
5. Pregnancy and breastfeeding: Due to limited research, pregnant and breastfeeding women are generally advised to avoid PQQ supplementation unless directed by a healthcare provider [1].

PQQ could be a game-changer for (skin) health and beauty. While the science looks promising, we're still in the early stages of understanding all that PQQ can do. As with any supplement or skincare ingredient, always consult a qualified healthcare professional to determine what the most suitable approach is for your health and beauty goals. 

Take care
Anne-Marie
​
References:
[1] Harris, C. B., et al. (2013). Dietary pyrroloquinoline quinone (PQQ) alters indicators of inflammation and mitochondrial-related metabolism in human subjects. J Nutr Biochem, 24(12), 2076-2084.
[2] Akagawa M, et al. Recent progress in studies on the health benefits of pyrroloquinoline quinone. Bioscience, Biotechnology, and Biochemistry. 2016;80(1):13-22
[3] Misra, H. S., et al. (2012). Pyrroloquinoline-quinone: a reactive oxygen species scavenger in bacteria. FEBS Lett, 586(22), 3825-3830.
[4] Qiu, X. L., et al. (2009). Protective effects of pyrroloquinoline quinone against Abeta-induced neurotoxicity in human neuroblastoma SH-SY5Y cells. Neurosci Lett, 464(3), 165-169.
​[5] Chowanadisai, W., et al. (2010). Pyrroloquinoline quinone stimulates mitochondrial biogenesis through cAMP response element-binding protein phosphorylation and increased PGC-1alpha expression. J Biol Chem, 285(1), 142-152.
[6] Stites, T., et al. (2006). Pyrroloquinoline quinone modulates mitochondrial quantity and function in mice. J Nutr, 136(2), 390-396.
[7] Bauerly, K., et al. (2011). Altering pyrroloquinoline quinone nutritional status modulates mitochondrial, lipid, and energy metabolism in rats. PLoS One, 6(7), e21779.
[8] Zhang, Y., et al. (2009). Neuroprotective effects of pyrroloquinoline quinone against rotenone injury in primary cultured midbrain neurons. Neurosci Lett, 455(3), 174-179.
[9] Nakano, M., et al. Effects of oral supplementation with pyrroloquinoline quinone on stress, fatigue, and sleep. Funct Foods Health 2012
[10] Liu, Y., Jiang, Y., Zhang, M., Tang, Z., He, M., Bu, P., & Li, J. (2020). Pyrroloquinoline quinone ameliorates skeletal muscle atrophy, mitophagy and fiber type transition induced by denervation via inhibition of the inflammatory signaling pathways. Annals of Translational Medicine, 8(5), 207.
[11] Wen, J., Shen, J., Zhou, Y., Zhao, X., Dai, Z., & Jin, Y. (2020). Pyrroloquinoline quinone attenuates isoproterenol hydrochloride-induced cardiac hypertrophy in AC16 cells by inhibiting the NF-κB signaling pathway. International Journal of Molecular Medicine, 45(3), 873-885.
[12] Tamakoshi, M., Suzuki, T., Nishihara, E., Nakamura, S., & Ikemoto, K. (2023). Pyrroloquinoline quinone disodium salt improves brain function in both younger and older adults. Food & Function, 14(6), 3201-3211.
[13] Zhang, Q., Zhang, J., Jiang, C., Qin, J., Ke, K., & Ding, F. (2014). Involvement of ERK1/2 pathway in neuroprotective effects of pyrroloquinoline quinine against rotenone-induced SH-SY5Y cell injury. Neuroscience, 270, 183-191.
[14] Zhang, Q., Shen, M., Ding, M., Shen, D., & Ding, F. (2011). The neuroprotective effect of pyrroloquinoline quinone on traumatic brain injury. Journal of Neurotrauma, 28(3), 359-366.
[15] Yamaguchi, K., Sasano, A., Urakami, T., Tsuji, T., & Kondo, K. (1993). Stimulation of nerve growth factor production by pyrroloquinoline quinone and its derivatives in vitro and in vivo. Bioscience, Biotechnology, and Biochemistry, 57(7), 1231-1233.
[16] Mohamad Ishak NS, Ikemoto K. Pyrroloquinoline-quinone to reduce fat accumulation and ameliorate obesity progression. Front Mol Biosci. 2023 
[17] Mitsugu Akagawa et al. Bioscience, Biotechnology, and Biochemistry Recent progress in studies on the health benefits of pyrroloquinoline quinone 2015
[18] Kazuto Ikemoto et al. The effects of pyrroloquinoline quinone disodium salt on brain function and physiological processes The Journal of Medical Investigation 2024
[19] Kowalczyk P, Sulejczak D, Kleczkowska P, Bukowska-Ośko I, Kucia M, Popiel M, Wietrak E, Kramkowski K, Wrzosek K, Kaczyńska K. Mitochondrial Oxidative Stress-A Causative Factor and Therapeutic Target in Many Diseases. Int J Mol Sci. 2021
[20] Guo C, Sun L, Chen X, Zhang D. Oxidative stress, mitochondrial damage and neurodegenerative diseases. Neural Regen Res. 2013
[21] Jonscher KR, Chowanadisai W, Rucker RB. Pyrroloquinoline-Quinone Is More Than an Antioxidant: A Vitamin-like Accessory Factor Important in Health and Disease Prevention. Biomolecules. 2021 
[22] Zhang C, Wen C, Lin J, Shen G. Protective effect of pyrroloquinoline quinine on ultraviolet A irradiation-induced human dermal fibroblast senescence in vitro proceeds via the anti-apoptotic sirtuin 1/nuclear factor-derived erythroid 2-related factor 2/heme oxygenase 1 pathway. Mol Med Rep. 2015 
[23] Li J, Liu M, Liang S, Yu Y, Gu M. Repression of the Antioxidant Pyrroloquinoline Quinone in Skin Aging Induced by Bmi-1 Deficiency. Biomed Res Int. 2022 
[24] Qin R, Sun J, Wu J, Chen L. Pyrroloquinoline quinone prevents knee osteoarthritis by inhibiting oxidative stress and chondrocyte senescence. American Journal of Translational Research. 2019
[25] Lee, J.-J.; Ng, S.-C.; Hsu, J.-Y.; Liu, H.; Chen, C.-J.; Huang, C.-Y.; Kuo, W.-W. Galangin Reverses H2O2-Induced Dermal Fibroblast Senescence via SIRT1-PGC-1α/Nrf2 Signaling. Int. J. Mol. Sci. 2022, 23, 1387. 

Reading the instructions on cleansing and care products can be misleading. When do I pat my skin dry first or when do I apply the product on damp skin? Even many recommendations from skin care guru's or skinfluencers are not completely correct. 

In general it is recommended to apply a serum, eye care or moisturising / hydrating care product on damp skin, or immediately after bathing for the following reasons:

Increased Absorption
The primary benefit of applying skin care products to damp skin is that the skin is more receptive to the ingredients. Water helps to increase the hydration levels of the skin cells, which then improves the absorption of the skincare products. When the skin is damp, the skin's surface is more permeable, allowing the ingredients in the skin care products to penetrate deeper into the skin, and work their magic. Absorbing the ingredients more effectively, this leads to better results.
The exception are products which require a very low pH level to penetrate, and be more effective, for example L-Ascorbic Acid (Vitamin C) and chemical exfoliating "acids" like hydroxy acids. The reason is that water has a pH level of 7-8, acidic formulations will be "neutralised" on damp skin.

Better hydration
Applying skin care products to damp skin helps to lock in moisture, leaving your skin feeling soft, supple, and hydrated. Hydration is critical for the skin because it helps to maintain and restore the skin's barrier function. The skin barrier protects the skin from losing hydration and prevents irritants and bacteria from entering. Applying serums and moisturisers on damp skin, increases the hydration benefits from the products.

Improved spreadability
Another advantage of applying skincare on damp skin is that it helps to improve the spreadability of the product. When we apply products such as serum or moisturiser to dry skin, they tend to settle in one area and can be challenging to spread evenly. On the other hand, when applied to damp skin, the skin care products can spread easily and evenly across the skin surface, ensuring maximum coverage and benefit.
The exception are lipid rich products which are hydrophobe (water repelling), for example ointments, they might not spread evenly or easy on damp skin.

Enhanced performance
Applying skin care products to damp skin has been shown to improve their performance. This is because when products are applied to damp skin, they are less likely to evaporate, and the ingredients remain active for longer. This increased contact time with the skin leads to better, more effective results.
The exception are products containing vitamin A, retinoids, tretinoin, retinal, retinol, retinaldehyde as damp skin increases the risk of irritation.

Sensitive and hyper-sensitive skin
Usually people with sensitive and hyper-sensitive skin have an impaired skin barrier function, hence ingredients will penetrate better in comparison to a resilient and well-functioning skin barrier. Applying products on (hyper)sensitive skin will therefore increase the risk of irritations. Be mindful which ingredients you use and use a pH rebalancing toner after cleansing and prior to any serum or care product you use. A toner is anyway an affordable product, which I highly recommend to use in every skin care routine. Read more.

Study results on patients with dry skin and healthy volunteers
In healthy subjects, compared to at control sites, the Stratum Corneum Water Content (SCW) was significantly higher at sites treated with the moisturizer immediately after bathing, with 1.0 and 2.0 mg/cm2 of the moisturizer, and with once- and twice-daily applications.
In patients with dry skin, the SCW was significantly higher compared to control sites after 8 weeks when the moisturizer was applied twice daily. Read more.

Take care.

Glycation is one of the basic root causes of endogeneous (intrinsic) skin ageing and a very challenging one or almost impossible one to reverse. Glycation is an ageing reaction which begins in early life, developing clinical symptoms at around 30, and progressively accumulates in tissues and skin due to the glycated collagens that are difficult to be decomposed. Glycation occurs naturally in the body when sugars react with proteins and lipids to form advanced glycation end products (AGEs). AGEs can be exogenously ingested (through food consumption), inhaled via tobacco or endogenously produced and formed both intracellularly and extracellularly. AGE modifications lead to dermal stiffening, diminished contractile capacity of dermal fibroblasts, lack of elasticity in the connective tissues, contribute to hyperpigmentation and a yellowish skin appearance. The formation of AGEs is amplified through exogenous factors, e.g., ultraviolet radiation. 

AGEs cause changes in the skin through 3 processes:

1. AGEs interact with specific cell receptors, altering the levels of soluble signaling molecules, such as cytokines, hormones, and free radicals.
2. In the process of non-enzymatic glycation reaction, a large number of reactive oxygen radicals are released, creating a state of oxidative stress, leading to a significantly reduced level of glutathione, Vitamin C, and Vitamin E in the body. This causes synthetic disorders of collagen in skin tissues. 
3. AGEs alter the physical and biological properties of the original extracellular matrix proteins, such as collagen. 

Many cells have AGEs receptors on the surface, such as macrophages, mesangial cells, fibroblasts, and endothelial cells, through which their function can be affected. They induce oxidative stress and trigger inflammatory pathways by forming crosslinks, altering protein structure, or by binding to AGEs receptors. AGEs cause cellular dysfunction through the modification of intracellular molecules and accumulate in tissues with ageing. This causes the skin and connective tissue to harden and lose their ability to regenerate healthy cells. They cause damage to extracellular proteins like collagen and elastin fibers, which are crucial for maintaining skin structure and firmness. This damage leads to the breakdown of these fibers. AGEs can also affect intracellular proteins like vimentin. AGEs can act as a catalytic site for free radical formation, exacerbate intracellular oxidative stress, and increase ROS production through a variety of mechanisms, reducing glutathione (skin's own anti-oxidant) storage, and activation of protein kinase C, etc., to accelerate the production and accumulation of AGEs. 

One study published in the Journal of Investigative Dermatology found that levels of AGEs were higher in the skin of older individuals compared to younger ones. The study also showed that there was a correlation between the level of AGEs and the severity of skin ageing. This suggests that inhibiting the production or accumulation of AGEs in the skin is a potential target for anti-ageing interventions or skin ageing management.

AGEs are complex and heterogeneous, more than a dozen AGEs have been detected (however not all) in tissues and can be divided into three categories according to their biochemical properties. 
​AGEs are formed through four pathways:

1. the Maillard reaction (non enzymatic reaction between amino groups of proteins and reducing sugars, binding sugars to proteins)
2. sugars auto-oxidation pathway (metal-catalyzed auto-oxidation of glucose or Wolff pathway) 
3. lipid peroxidation pathway (acetyl alcohol pathway)
4. polyols pathway (glucose is converted into fructose via the polyol pathway, which accelerates the production of AGEs)

GLYCATION INHIBITION IS KEY 
AGEs can be crosslinked through side chains to form a substance of very high molecular weight, which is not easily degraded. The consequences from skin glycation are irreversible. This makes prevention or inhibition of the process the best potential strategy to maintain skin health and ageing skin management. One way to do this is by altering the diet to reduce the intake of sugars and carbohydrates, which are known to contribute to glycation. Several studies have found that reducing sugar intake can result in significant improvements in skin health, including reducing wrinkles and improving skin texture. 

AGE inhibitors
Another potential strategy is the use of topical agents that inhibit the formation or accumulation of AGEs in the skin. One study published in the Journal of Cosmetic Science found that a cream containing carnosine, a peptide that inhibits glycation, improved skin elasticity and reduced the appearance of wrinkles in individuals with ageing skin. Skincare containing NAHP or Acetyl Hydroxyproline inhibits the formation of AGEs significantly (in vitro), most likely through a mechanism where NAHP competes with the proteins for the sugar. Finally, NAHP sacrifices itself in place of the proteins and gets (at least partially) glycated. NAHP also prevents loss of cellular contractile forces in a glycated in vitro dermis model and counteracts the diminished cell-matrix interaction that is caused by glyoxal-induced AGE formation. 

Take-aways from a study published in the International Journal of Cosmetic Science [2]:
1. NAHP significantly and dose-dependently inhibited the formation of advanced glycation end-products (AGEs) in a protein solution.
2. NAHP dose-dependently inhibited the formation of N-(carboxymethyl)lysine (CML), a specific AGE.
3. In fibroblast-populated collagen lattices, NAHP prevented the glycation-induced disturbance of fibroblast contractile capacity.
4. Ex vivo application of NAHP to skin explants decreased AGE fluorescence compared to glucose-treated samples.

​Anti-Oxidants
I would suggest to combine those ingredients with an ingredient like Licochalcone A. Numerous high ranked publications support that Licochalcone A protects cells from oxidative stress mediated by e.g. UV and HEVIS (blue light) induced reactive oxidative species (ROS). Due to the activation and nuclear translocation of the transcription factor NrF2, the expression of anti-inflammatory, antioxidant and detoxifying enzymes are induced. These enzymes protect the skin cells (like keratinocytes and fibroblasts) from ROS-induced damage, like lipid peroxidation and DNA as well as protein damage. If Licochalcone A is combined with L-Ascorbic Acid, (the most active form of Vitamin C), it supporting skin's own collagen production, provides superior biological cell protection amongst other relevant benefits. Vitamin C (and E) has shown to inhibit protein glycation [4].

SPRAY TAN
A study in Redox Biology indicates that sunless tanning with dihydroxyacetone (DHA) causes glycation and potential DNA damage in the epidermis [1].:
1. Glycation: DHA exposure led to the formation of advanced glycation end products (AGEs) in epidermal cells, confirmed by mass spectrometric detection of N-ε-(carboxyethyl)-l-lysine (CEL).
2. DNA damage: DHA induced a cellular stress response, including activation of stress-related genes and phosphoprotein signaling. While not directly measuring DNA damage, these responses are often associated with cellular stress that can lead to DNA damage.
3. Significance: The effects were observed at low millimolar concentrations of DHA, relevant to topical application. The stress response was rapid and pronounced, occurring within minutes of exposure.
4. Location: The effects were primarily observed in epidermal cells and reconstructs, with no mention of dermal effects.
This study suggests that sunless tanning with DHA may not be as safe as previously thought, warranting further investigation into its long-term effects on skin health [1], however no need to panic as this negative effect is only seen in the top layer of the skin.

DOUBLE TROUBLE: GLYCATION + UVB  [3]
The combination of GO-AGEs and UVB exposure has a more pronounced effect on skin inflammation and oxidative stress than either factor alone. This suggests a synergistic relationship between glycation and UV exposure in accelerating skin aging processes.
1. GO-AGEs combined with UVB irradiation significantly increased the secretion of pro-inflammatory cytokines (IL-1β, IL-6, IL-8) in skin cells compared to either GO-AGEs or UVB alone.
2. The GO-AGEs + UVB treatment group showed a more than three-fold increase in IL-6 and IL-8 mRNA levels compared to other groups.
3. GO-AGEs + UVB treatment induced significantly higher release of nitric oxide (NO) compared to other groups.
4. The combination of GO-AGEs and UVB enhanced reactive oxygen species (ROS) release, creating about 1.5 times more oxidative stress compared to control and other groups.
5. Cell viability was notably affected in the GO-AGEs, UVB, and GO-AGEs + UVB treatment groups compared to the control group.
These findings are significant as they demonstrate that the combination of GO-AGEs and UVB exposure has a more pronounced effect on skin inflammation and oxidative stress than either factor alone. This suggests a synergistic relationship between glycation and UV exposure in accelerating skin aging processes. Use sunscreen daily.
.
GLYCATION AND SKIN HEALTH
Acne
In addition to its role in ageing, glycation in the skin has also been linked to a range of skin health problems. One study published in the Journal of Cosmetic Dermatology found that the level of AGEs in the skin was significantly higher in individuals with acne than in those without acne. The study also showed that treating acne with a topical antibiotic significantly reduced the levels of AGEs in the skin.
Atopic Dermatitis
Another study published in the Journal of Investigative Dermatology found that individuals with atopic dermatitis had higher levels of AGEs in their skin than healthy individuals. This suggests that glycation may play a role in the development of inflammatory skin conditions.
Diabetes + Woundhealing
The correlation between high sugar levels and skin ageing can be seen in diabetic patients, where one-third of this population has skin complications. A prominent feature of ageing human skin is the fragmentation of collagen fibers, which severely damages the structural integrity and mechanical properties of the skin. Elevated levels of MMP-1 and MMP-2 and higher crosslinked collagen in the dermis of diabetic skin lead to the accumulation of fragmented and crosslinked collagen, thereby impairing the structural integrity and mechanical properties of dermal collagen in diabetes. Collagen crosslinking makes it impossible for them to easily repair, resulting in reduced skin elasticity and wrinkles. Keratinocytes and fibroblasts are the main cells involved in wound healing, but due to the high glucose (HG) microenvironment in diabetics, the functional state of these cells is impaired, thereby accelerating cellular senescence (programmed cell death).

Conclusion
We can't completely stop the glycation process, therefore it's important that we inhibit it from a young age onwards, hence monitor the sugar intake of our children, use daily SPF and invest in good dermo-cosmetic products containing ingredients like NAHP and powerful anti-oxidants like L-Ascorbid Acid (Vitamin C is needed for the production of collagen) and Licochalcone A (also anti-inflammatory). Preventing signs of ageing, specifically caused by glycation is most effective. If your skin shows (advanced) signs of ageing, you can get visible improvement using skin component (hyaluron, collagen and elastin) bio-stimulating ingredients like Retinol, Bakuchiol, Arctiin, Creatine or Glycine Saponin. Consult your dermatologist if you wish to improve your skin's appearance or skin health issues.

Take care
Anne-Marie

References
[1] Perer J, Jandova J, Fimbres J, Jennings EQ, Galligan JJ, Hua A, Wondrak GT. The sunless tanning agent dihydroxyacetone induces stress response gene expression and signaling in cultured human keratinocytes and reconstructed epidermis. Redox Biol. 2020 Sep;36:101594.
[2] Knoblich C, et al. N‐acetyl‐L‐hydroxyproline – A potent skin anti‐ageing active preventing advanced glycation end‐product formation in vitro and ex vivo. Int J Cosmet Sci. 2023;1-10. doi:10.1111/ics.12930
[3] Sultana, R., Parveen, A., Kang, MC. et al. Glyoxal-derived advanced glycation end products (GO-AGEs) with UVB critically induce skin inflammaging: in vitro and in silico approaches. Sci Rep 14, 1843 (2024). https://doi.org/10.1038/s41598-024-52037-z
[3] Sadowska-Bartosz I, Bartosz G. Prevention of protein glycation by natural compounds. Molecules. 2015 Feb 16;20(2):3309-34. doi: 10.3390/molecules20023309. PMID: 25690291; PMCID: PMC6272653.

Special thanks: Ph.D. dr Julia M. Weise Manager Biological Testing & Dorothea Schweiger Lab Manager Facial Skin Biology Beiersdorf HQ Hamburg

Our life expectance is increasing and the average age when menopause occurs didn't change much in the last decade. This is why more women will have to care for post menopause skin for a longer time. During and after menopause our skin will go through some changes and might even become problematic. In this blog post I will have a closer look into these changes.

Change
During the start of menopause, also called peri-menopause, women will notice some changes to their skin. This is because estrogen levels start to decline (-35% between age 35-50) and as estrogen level decline, androgen level proportionately become more dominant. As a result, the majority of women experience drier skin. Or when the hormone levels are differently balanced they may get a more oily skin or develop acne tarda (adult acne), because the oil gland activity is increased. Another problem is that the skin's pH level will increase, which will impact skin health, barrier and microflora or microbiome. A higher pH value may result in problematic skin.

Loss of biological activity 
Around this period the metabolic biological activity in the skin will decrease faster than in our 20s or 30s. The production of important components like hyaluronic acid (filling + hydration), collagen (strength + structure) and elastin (flexibility + stretch) by fibroblasts (a very important skin cell) isn't sufficient, while the speed of their degradation is inclining because the skin's natural resilience against damaging free radical activity is reduced and the activity of degradation enzymes, like hyaluronidase, collagenase and elastase is elevated. Therewith the presence of those important skin components is declining 30% in the first years. This leads to more advanced signs of ageing skin and an overall loss of skin quality: skin firmness, skin surface eveness, skin tone eveness and glow (Goldie, Clin Cosmet Invest Dermatol, 2021). 

Solution
Skin ageing is a multifaceted continuous biological degenerative process, with an impact on overall skin quality, self perceived attractiveness, confidence and comfort (Quality of Life). The optimal solution should improve all 4 emergent perceptual categories or EPG's of skin quality (an important component of human attractiveness) as mentioned above. This can be achieved by supporting skin's own resilience against the inclined loss by degradation (reduce free radical and enzymatic activity) and increase skin's own biological activity, hence skin's own production of hyaluron, collagen and elastin with bio-active ingredients or bio-stimulators and inhibit human tyrosinase activity (reduce age spots). I will explain the 4 key actions below:

1. Bio-stimulators
Some evidence based bio-actives we can find in skincare are:

• 52 kDa Micro-Hyaluron (stimulation of hyaluron production with 209%: hyaluron-filler)
• Creatine (stimulation of collagen I and IV by + 35%  and elastin with +36%)
• Glycine Saponin (stimulation of hyaluron production +256% collagen +49% elastin +19%) which is also a powerful anti-oxidant

There are very good in-office treatments for bio-stimulation.

2. Enzyme inhibitors
Some ingredients in skincare which inhibit enzymatic degradation are:

• Enoxolone (reduces hyaluronidase I activity by >50%)
• Arctiin (reduces HN-elastase activity by 79%) and is also an anti-oxidant

3. Anti-oxidants
Damaging free radical activity is increased in mature skin and ROS (Radical Oxidative Species) increase degradation of all components, enzymatic degradation and human tyrosinase activity, a powerful cocktail of anti-oxidants is a "must-have". The combination of fresh activated L-Ascorbic-Acid (primary defence with instant neutralisation of extra-cellular free radicals) and Licochalcone A (secondary defence with long-lasting intracellular stress protection is a valuable addition in any day or nighttime skincare regimen. Licochalcone A is moreover one of the most powerful anti-oxidants (if not the most powerful one) proven to reduce (deep) oxidative stress from High Energy Visible Light or HEVIS. As we know, free radicals from HEVIS damage the important skin-cell called the fibroblast and increase the risk of age spots. 

4. Human tyrosinase inhibition
A relatively new, effective and safe ingredient in skincare which was tested on inhibiting human tyrosinase is Thiamidol. Other ingredients in skincare were tested on mushrooms (Hornyak, Journal of Investigative Dermatology 2018 & Mann et al. 2018) and are not potent in reducing human tyrosinase activity. It took 10 years of pioneering research (dr Ludger Kolbe) and comparing 50.000 actives to patent and market it. In the mean time Thiamidol is loved and recommended globally by many dermatologists and evidence based with 35+ studies including >2000 participants with all Fitzpatrick phototypes. 

Every AM routine should at least have a skincare product with SPF of 15 or higher.
An improvement of skin quality leads to an improvement of quality of life (van Geloven et al. EADV 2022). 
​
Hope this was helpful.
Take care

Vitamin C is a "must have" skin care ingredient our skin needs at any age.
 
One of the best researched skin care ingredients and proven to be very beneficial for skin is Vitamin C. Our skin uses Vitamin C as an anti-oxidant and the dermal fibroblasts need Vitamin C for the production of collagen. Two very good reasons to add this ingredients into your daily skincare routine whether you are twenty or eighty. Moreover, our skin depends on us for the needed supply, as our skin is not able to produce Vitamin C itself.
 
We can either include enough Vitamin C in our diet or apply Vitamin C topically there where we need it the most. Usually this is the skin which is exposed to (sunlight) as this increases damaging free radical activity in our skin. An active form of vitamin C can reduce the free radical activity, which we call anti-oxidative effect. 
 
There are 4 things to consider when buying a skincare product containing Vitamin C:

1. Vitamin C needs to be used in an active form. Fresh reconstituted (mixed) L-Ascorbic Acid is the most active form of Vitamin C. A stabilized form of Vitamin C is not active anymore and therewith not as effective or not effective at all.
2. The formula has to have a low or very low pH value in order for the vitamin C to penetrate well into the skin.
3. The percentage of vitamin C needs to be above 8 and not over 20 to be optimal. For a good balance between great efficacy and tolerability, 10% fresh L-Ascorbic Acid is just right. Higher might not add much efficacy, but could create tolerability issues, especially for more sensitive skin.
4. The packaging and application form should protect the formula from light & air as much as possible. A dropper for example will expose the formula to air with every use.

 
Day or night?
Some recommend to use Vitamin C during the night, as the active form of Vitamin C will oxidize in daylight. Hence, your skin can benefit from the Vitamin C longer during the night. I would recommend Vitamin C to be used during daytime (thus added to your morning routine), as we need protection from damaging free radicals the most during daytime and the oxidization of Vitamin C is actually a sign that the ingredient is doing it’s job! It’s even better to add Vitamin C both to your day & night time skincare routine.
 
Is L-Ascorbid Acid enough?
Vitamin C is counteracting free radicals from UV light. However, UV is not the only damaging light form as there is also High Energy Visible Light or abbreviated HEVIS. This penetrates even deeper into the skin where also the dermal fibroblasts reside. The dermal fibroblasts are our collagen and hyaluronic acid producing cells and a key target in an effective anti-ageing skincare strategy. Lichochalcone A (Licorice-root extract) has proven to be the most potent anti-oxidant to protect the dermal fibroblasts and neutralize free radicals from HEVIS. Moreover, Lichocalcone A increases Glutathione, which is a skin’s own anti-oxidant. Licorice-root extract is an anti-ageing hero.

Summary
The combination of Vitamin C and Lichocalcone A will protect our skin and dermal fibroblasts from free radical damage by UV and HEVIS and will provide superior biological cell protection in comparison to Vitamin C only. For me this is a good reason to use a product containing both ingredients as a first step after my cleansing routine in the morning. If you have sensitive eyes, I recommend to use an eye care prior, which will form a barrier to help to prevent the low pH Vitamin C product to migrate into the eye area. Afterwards you can use the other products of your skincare routine. I would like to put emphasis on using a SPF of 30 or higher during the day. This will not only help to protect your skin, but also support the anti-oxidative benefits and make them last longer.
 
Hope this was helpful.
Take care!