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3/3/2024 Comments The vitamin D dilemma
Balancing Health, Beauty, and vitamin D
Like many who promote skin health and beauty, I often find myself navigating the delicate balance between the benefits and risks of sun exposure. Moderate exposure to sunlight is essential for vitamin D production, triggers beneficial stress responses and DNA repair mechanisms in our bodies through hormesis, promoting overall health and well-being. However, excessive sun exposure can overwhelm these protective systems, leading to harmful effects such as skin damage and increased cancer risk. Vitamin D is a crucial prohormone that plays a vital role in numerous functions, including: 1. Bone health and calcium absorption [1] 2. Immune system modulation [1] 3. Regulation of up to 2,000 genes involved in various biological processes [1] – more details below 4. Potential cancer prevention [1] THE SUNLIGHT PARADOX: HEALTH BENEFITS VS. RISKS Benefits of sunlight exposure 1. Vitamin D production (80-90%) [1] 2. Regulation of circadian rhythms and improved sleep quality [1] 3. Mood enhancement and potential alleviation of depressive symptoms [1] 4. Lowering of blood pressure through nitric oxide production in the skin [1] Risks of excessive sun exposure 1. DNA damage, including the formation of cyclobutane pyrimidine dimers (CPDs) and 6-4 photoproducts (6-4PPs) [2] 2. Oxidative stress and generation of reactive oxygen species (ROS) [2] 3. Premature skin aging and hyperpigmentation [2] 4. Increased risk of skin cancers, including melanoma [2] Health benefits of vitamin D 1. Bone health: Promotes calcium absorption and bone mineralization, preventing conditions like rickets and osteoporosis [3] 2. Muscle strength and function: Helps maintain muscle strength and reduce the risk of falls, especially in older adults [4] 3. Immune system support: Modulates immune responses and may reduce the risk of autoimmune diseases [5] 4. Heart health: Low vitamin D levels have been linked to increased risk of heart diseases, though the exact relationship is unclear [6] 5. Reduced risk of severe illnesses: May make severe flu and COVID-19 infections less likely [7] 6. Mood regulation: May play a role in regulating mood and decreasing the risk of depression [8] 7. Weight management: There is a relationship between (low) vitamin D levels and (over)weight, though the exact nature is not fully understood [9] 8. Reduced risk of multiple sclerosis (MS): Low levels of vitamin D are linked with an increased risk of MS [10] 9. Brain health: Supports brain cell activity and may have neuroprotective properties 10. Anti-inflammatory effects: Has anti-inflammatory properties that support overall health Skin health and beauty benefits of Vitamin D 1. Skin barrier function: Regulates the generation of keratinocytes, which are critical for maintaining the skin barrier [11] 2. Skin immunity: Indispensable for the activation of immune cells in the skin, supporting its protective function [12] 3. Antimicrobial effects: Has direct antimicrobial effects in the skin, helping to fight off pathogens [13] 4. Regulation of sebaceous glands: Important for growth regulation and optimum functioning of sebaceous glands [14] 5. Photoprotective effects: Topical application may offer some protection against UV-induced skin damage [15] 6. Wound healing: Promotes repair of damaged tissue and restoration of the skin's barrier mechanism [16] 7. Anti-aging effects: May have antiaging effects on the skin, though more research is needed in this area [17] 8. Skin cell differentiation and growth: Plays a role in the proliferation and differentiation of skin cells [18] 9. Melanin regulation: Protects the epidermal melanin unit and restores melanocyte integrity [19] 10. Potential role in skin conditions: May play a role in managing conditions like psoriasis, atopic dermatitis, and vitiligo [20] 11. Skin hydration: Topical application of vitamin D improves skin hydration and symptoms of dry skin [21] VITAMIN D AND PARP A study published in the International Journal of Molecular Medicine demonstrated that the active form of vitamin D inhibits poly(adenosine diphosphate-ribose) polymerase (PARP). PARP is an enzyme that plays a crucial role in DNA repair. PARP acts like a cellular "first responder" for DNA damage, initiating the repair process to keep our genetic material intact.
VITAMIN D SYNTHESIS IN THE SKIN
When UVB rays from sunlight hit the skin, they trigger the production of vitamin D [22]: 1. UVB radiation converts 7-dehydrocholesterol in the skin to previtamin D3 2. Previtamin D3 then isomerizes to vitamin D3 3. Vitamin D3 is transported to the liver and converted to 25-hydroxyvitamin D [25(OH)D] 4. Finally, 25(OH)D is converted to the active form, 1,25-dihydroxyvitamin D (calcitriol), in the kidneys FACTORS INFLUENCING VITAMIN D PRODUCTION 1. Latitude: Higher latitudes receive less UVB radiation, especially during winter months [23] 2. Time of day: UVB rays are strongest at solar noon [23] 3. Season: Vitamin D production is lower in winter due to reduced UVB radiation [23] 4. Skin pigmentation: Darker skin requires longer sun exposure to produce the same amount of vitamin D as lighter skin [24] 5. Age: Older adults produce less vitamin D from sun exposure [23] 6. Sunscreen use: High SPF sunscreens can significantly reduce vitamin D production [25] 7. Air pollution: Reducing UVB radiation reaching the earth's surface EPIGENETICS Vitamin D regulates up to 2000 genes, involving both direct genomic effects and epigenetic mechanisms. 1. Vitamin D receptor (VDR) binding The active form of vitamin D, 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], binds to the vitamin D receptor (VDR). This liganded VDR then forms a heterodimer with the retinoid X receptor (RXR) [26][27]. 2. Direct gene regulation The VDR/RXR complex binds to specific DNA sequences called vitamin D response elements (VDREs). These VDREs can be located in promoter regions, introns, or even far from the transcription start sites of target genes [26][27][28]. 3. Epigenetic mechanisms
VDR interacts with numerous coregulatory proteins that can either activate or repress gene transcription [26][28]. 5. Genome-wide effects Genome-wide studies have shown that VDR can bind to hundreds of genomic loci, regulating gene activity at various locations, including many kilobases upstream or downstream of transcription start sites [26][28]. 6. Primary and secondary target genes Vitamin D regulates both primary target genes (directly controlled by VDR) and secondary target genes (controlled by transcriptional regulators encoded by primary targets) [26][30]. 7. Cell-specific regulation The effects of vitamin D on gene expression are highly cell-specific, depending on the epigenetic landscape of each cell type [26][31]. 8. Dose-dependent effects Higher doses of vitamin D supplementation have been shown to affect the expression of more genes in a dose-dependent manner [32]. RECOMMENDATIONS FOR SUN EXPOSURE Factors such as latitude, season, cloud cover, and individual skin type can all affect vitamin D synthesis [33][34]. Additionally, morning and evening sun contains less UVB radiation, which is necessary for vitamin D production, so longer exposure times may be needed [34]. Health experts often recommend midday sun exposure for optimal vitamin D production, while dermatologists typically advise against it due to increased UV intensity. Considerations 1. Midday sun (higher UVB) is more efficient for vitamin D production, requiring shorter exposure times [35] 2. Shorter exposure times may reduce overall UV damage risk [35] 3. Individual factors, such as skin type and location, should be considered when making recommendations [35] Impact of skin type Darker skin requires longer exposure times due to higher melanin content [1][36]
Type VI: 25.25 minutes [37]
Recommendation fair skin (Fitzpatrick Types I-III)
Recommendation darker skin (Fitzpatrick Types IV-VI) 1. Longer sun exposure times are needed, typically 15-30 minutes 3-5 times per week [40] 2. Consider exposing larger body surface areas when possible [40] 3. Sun exposure during midday hours may be more effective for vitamin D production [35] Variations based on location and season
Sunscreen and vitamin D production Sunscreen can decrease vitamin D3 formation in the skin. The effect varies based on coverage, thickness, and SPF. [36] Nevertheless, I would highly recommend the always use sunscreen on face, neck and décolletage as and expose skin surface areas to sunlight in the shortest amount possible to minimise DNA damage and the risk of sunburn and skin cancer. [1][36] ALTERNATIVE STRATEGIES FOR VITAMIN D SUFFICIENCY For many people, especially those living at higher latitudes, with darker skin, or those unable to obtain adequate sun exposure, or at high risk for skin damage, vitamin D supplementation may be necessary to maintain optimal levels, particularly during winter months [33][42]. However, excessive vitamin D3 levels can have negative health effects. 1. Dietary sources: Fatty fish, egg yolks, and fortified foods 2. Vitamin D3 supplements: The recommended dose is 1000 units per 25 pounds bodyweight (>4000 IU or 100 micrograms only under medical supervision) and taken alongside vitamin K2 and magnesium for a synergistic effect. Best is to take it in the morning in line with circadian rhythms. Consult with a healthcare provider for appropriate dosage and monitor your levels. 3. UVB lamps: Under medical supervision, these can be used for controlled vitamin D production. For the average adult a range of 30-50 ng/mL (75-125 nmol/L) is seen as optimal, 50 ng/mL (125 nmol/L) may be too high and below 20 ng/mL (50 nmol/L) are generally considered deficient. Achieving optimal vitamin D levels while protecting skin health requires a personalised approach. I hope that the information provided will help you to navigate the delicate balance between sun exposure benefits, risks and the use of sunscreens. Always consult a healthcare professional, especially if you have a history of skin cancer or are at risk for vitamin D deficiency. Take care Anne-Marie References [1] Holick MF. Sunlight and vitamin D for bone health and prevention of autoimmune diseases, cancers, and cardiovascular disease. Am J Clin Nutr. 2004 [2] Cadet J, Douki T. Formation of UV-induced DNA damage contributing to skin cancer development. Photochem Photobiol Sci. 2018 [3] Holick MF. Vitamin D deficiency. N Engl J Med. 2007 [4] Bischoff-Ferrari HA et al. Prevention of nonvertebral fractures with oral vitamin D and dose dependency: a meta-analysis of randomized controlled trials. Archives of Internal Medicine. 2009 [5] Prietl B et al. Vitamin D and immune function. Nutrients. 2013 [6] Wang TJ et al. Vitamin D deficiency and risk of cardiovascular disease. Circulation. 2008 [7] Martineau AR et al. Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data. BMJ. 2017 [8] Anglin RE et al. Vitamin D deficiency and depression in adults: systematic review and meta-analysis. British Journal of Psychiatry. 2013 [9] Vimaleswaran KS et al. Causal relationship between obesity and vitamin D status: bi-directional Mendelian randomization analysis of multiple cohorts. PLoS Medicine. 2013 [10] Munger KL et al. Serum 25-hydroxyvitamin D levels and risk of multiple sclerosis. JAMA. 2006 [11] Bikle DD. Vitamin D metabolism and function in the skin. Molecular and Cellular Endocrinology. 2011 [12] Schauber J. et al. Injury enhances TLR2 function and antimicrobial peptide expression through a vitamin D–dependent mechanism. Journal of Clinical Investigation. 2007 [13] Liu PT et al. Toll-like receptor triggering of a vitamin D-mediated human antimicrobial response. Science. 2006 [14] Krämer C et al. Characterization of the vitamin D endocrine system in human sebocytes in vitro. Journal of Steroid Biochemistry and Molecular Biology. 2009 [15] Dixon KM, Deo SS, Wong G, Slater M, Norman AW, Bishop JE, Posner GH, Ishizuka S, Halliday GM, Reeve VE, Mason RS. Skin cancer prevention: a possible role of 1,25dihydroxyvitamin D3 and its analogs. Journal of Steroid Biochemistry and Molecular Biology. 2005 [16] Oda Y, Uchida Y, Moradian S, Crumrine D, Elias PM, Bikle DD. Vitamin D receptor and coactivators SRC2 and 3 regulate epidermis-specific sphingolipid production and permeability barrier formation. Journal of Investigative Dermatology. 2009 [17] Rinnerthaler M, Bischof J, Streubel MK, Trost A, Richter K. Oxidative stress in aging human skin. Biomolecules. 2015 [18] Bikle DD. Vitamin D regulated keratinocyte differentiation. Journal of Cellular Biochemistry. 2004 [19] Ranson M, Posen S, Mason RS. Human melanocytes as a target tissue for hormones: in vitro studies with 1α-25, dihydroxyvitamin D3, α-melanocyte stimulating hormone, and beta-estradiol. Journal of Investigative Dermatology. 1988 [20] Mostafa WZ, Hegazy RA. Vitamin D and the skin: Focus on a complex relationship: A review. Journal of Advanced Research. 2015 [21] Russell M. Assessing the relationship between vitamin D3 and stratum corneum hydration for the treatment of xerotic skin. Nutrients. 2012 [22] Wacker M, Holick MF. Vitamin D - effects on skeletal and extraskeletal health and the need for supplementation. Nutrients. 2013 [23] Webb AR, Engelsen O. Calculated ultraviolet exposure levels for a healthy vitamin D status. Photochem Photobiol. 2006 [24] Farrar MD, et al. Efficacy of a dose range of simulated sunlight exposures in raising vitamin D status in South Asian adults: implications for targeted guidance on sun exposure. Am J Clin Nutr. 2013 [25] Matsuoka LY, et al. Sunscreens suppress cutaneous vitamin D3 synthesis. J Clin Endocrinol Metab. 1987 [26] Fetahu IS, Höbaus J, Kállay E. Vitamin D and the epigenome. Front Physiol. 2014 [27] Carlberg C. Vitamin D and Its Target Genes. Nutrients. 2022 [28] Christakos S et al. Vitamin D: Metabolism, Molecular Mechanism of Action, and Pleiotropic Effects. Physiol Rev. 2016 [29] Voltan G et al. Vitamin D: An Overview of Gene Regulation, Ranging from Metabolism to Genomic Effects. Genes (Basel). 2023 [30] Veijo Nurminen et al. Front. Physiol., 05 March 2019 Sec. Integrative Physiology Primary Vitamin D Target Genes of Human Monocytes [31] Vassil Dimitrov et al. Vitamin D-regulated Gene Expression Profiles: Species-specificity and Cell-specific Effects on Metabolism and Immunity, Endocrinology, Volume 162, Issue 2, February 2021 [32] GrassrootsmHealth Nutrient Research Institute. Vitamin D Supplementation Amount Influences Change in Genetic Expression. [Internet]. 2018 [33] Wacker M, Holick MF. Sunlight and Vitamin D: A global perspective for health. Dermatoendocrinol. 2013 [34] Nagaria TD et al. The Sunlight-Vitamin D Connection: Implications for Patient Outcomes in the Surgical Intensive Care Unit. Cureus. 2023 [35] Rhodes LE, et al. Recommended summer sunlight exposure levels can produce sufficient (≥20 ng ml(-1)) but not the proposed optimal (≥32 ng ml(-1)) 25(OH)D levels at UK latitudes. J Invest Dermatol. 2010 [36] Ashley, R. (n.d.). Ask the Doctors - How much sunshine do I need for enough vitamin D? UCLA Health. [37] Yilmaz, B., & Karakas, M. (2024). UV index-based model for predicting synthesis of (pre-)vitamin D3 in human skin. Scientific Reports, 14(1), 3188. [38] Mead MN. Benefits of sunlight: a bright spot for human health. Environ Health Perspect. 2008 [39] American Academy of Dermatology. Sunscreen FAQs. [40] Farrar MD, et al. Efficacy of a dose range of simulated sunlight exposures in raising vitamin D status in South Asian adults: implications for targeted guidance on sun exposure. Am J Clin Nutr. 2013 [41] Miyauchi, M., & Nakajima, H. (2016). The solar exposure time required for vitamin D3 synthesis in the human body estimated by numerical simulation and observation in Japan. Journal of nutritional science and vitaminology, 62(5), 379-385. [42] Healthline How to Safely Get Vitamin D From Sunlight Ryan Raman, MS, RD — Updated on April 4, 2023
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