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 he anti-oxidative benefits and make them last longer.
 
Hope this was helpful.
Take care!

After about spending some time in bathtub or in the pool, we can notice that our skin on particularly finger tops and toes start to wrinkle up. This wrinkling effect is believed to have a function.

When wet, things tend to be more slippery and our sophisticated skin is designed to counteract this by wrinkling up in a pattern optimised to provide a drainage network that improves grip, much like the tires on a car according to a study. Link to original publication. However, other studies would contradict that there would be a functional benefit for so called aquatic wrinkles.

The osmosis theory
Water molecules moving trough a semipermeable membrane from a low concentration area to a high concentration area is a process called osmosis. The shrinking and expanding effects of osmosis takes place simultaneously outer layer of the skin, causing wrinkles.

The skin's outermost layer is also known as stratum corner could be responsible for this wrinkly reaction, The top layer of our skin consists of dead corneocytes. The longer these cells are attached to the skin, the bigger they are. The size of the corneocytes we actually use to objectively measure the skin's renewal and desquamation (shedding of cells) process. These dead (keratin containing) skin cells may absorb water and swell. The lower layer with living cells doesn't swell up. As top layer (which is increased in size) is still attached to the layer beneath, a wrinkly pattern is formed. The layer of dead skin cells is thicker at the palms of our hands and soles of our feet, the wrinkling effect is more evident. This response occurs more quickly in freshwater than seawater. Moreover, when we are exposed to water for a longer time, the water-repelling film on top of the outer layer of the skin may get impaired.

The sympathetic nervous system / microcirculation theory
It's known that there is a relationship between the wrinkling-effect and blood vessels constricting (narrowing) below the skin. When hands and feet are soaked in water, the nerve fibres in the skin shrink and the body temperature regulators loses volume. Therewith the top layer of the skin is pulled downward and the wrinkling pattern is formed. It is proven that wrinkling-effect response is impaired, if the nerves and/or blood vessels are damaged. Therewith the wrinkling effect can even be used to determine proper functioning of the sympathetic nervous system and/or skin's microcirculation. There is evidence that the wrinkling effect is impaired in patients suffering from diabetes: link to article. 

Regardless the cause, aquatic wrinkles disappear fast and the skin returns to normal once the water has evaporated.
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Take care.