Even today, when we talk about supplements, we think of vitamins, and in particular vitamin C. For some time now, almost magical properties have been attributed to products containing this micronutrient, such as treating colds or flu. But lately, vitamin C has appeared elsewhere: as an ingredient in cosmetic skin care creams. Vitamin C, whose formula is ascorbic acid, is an antioxidant. Since skin aging is largely caused by oxidative damage, it is reasonable to think that vitamin C could prevent this damage. However, this only happens if it penetrates the skin, which largely depends on the formulation.
Beneficial effects of vitamin C on the skin
Various research has shown that topically applied vitamin C can potentially improve the appearance of the skin. A recent review of studies found limited but positive evidence that vitamin C helps reduce the appearance of fine wrinkles and improves overall skin texture.
Other research has shown that vitamin C protects against photoaging (skin damage caused by sun exposure), ultraviolet-induced immunosuppression, and photocarcinogenesis, meaning it reduces the chances that exposure in the sun causes skin cancer. It also has an anti-aging effect by increasing collagen synthesis, stabilizing collagen fibers and decreasing the breakdown of collagen, a protein that maintains skin elasticity and softness.
Vitamin C also has a brightening effect, meaning it can help reduce hyperpigmentation and dark spots, an especially important benefit for people with sun damage or post-inflammatory spots resulting from sun damage. ‘acne. Studies indicate that ascorbic acid may inhibit tyrosinase, an enzyme necessary for the production of melanin, a substance that darkens the skin.
Vitamin C is found in the skin, and many of these effects occur when combined with vitamin E, as the two work synergistically to maximize the cells’ antioxidant defense. But the vitamin C used by skin cells is the one we have in our blood and which comes from our diet. Does it help to add extra vitamin C?
The problem of absorption through the skin
The effectiveness of vitamin C in creams depends on different factors, including concentration and stability. Ascorbic acid, in its pure form, is very unstable and can oxidize quickly upon contact with air or light. These oxidized versions of vitamin C are no longer effective.
In most cases, for a product to have effects, it must have a vitamin C concentration greater than 8%. However, different studies indicate that a concentration above 20% does not increase its effectiveness and, on the contrary, could cause irritation. This is why many creams contain between 10 and 20%.
Ascorbic acid is a hydrophilic molecule, i.e. soluble in water, which is problematic because the outer layer of the skin is hydrophobic, i.e. water-repellent. One way to increase absorption is to lower the pH, that is, to make the cream acidic, for example by adding ferulic acid.
Other common formulations of vitamin C are ascorbyl-6-palmitate and magnesium ascorbyl phosphate (MAP). These two molecules are lipophilic, that is to say soluble in fats, and stable at neutral pH. However, one study showed that daily application of MAP, ascorbyl-6-palmitate, and other ascorbic acid derivatives did not increase vitamin C levels in the skin.
What the studies indicate is that when we have low levels of vitamin C in the blood, some can be absorbed through the skin, again, with effectiveness that depends on the formulation and concentration. Very little is known about how much vitamin C can be absorbed from a cream. Recent studies suggest that when vitamin C is encapsulated in the famous liposomes (microscopic spheres of fat), its transport to the lower layers of the epidermis can be facilitated.
Possible side effects
Despite the benefits mentioned, not all skin types react in the same way to products containing vitamin C. At high concentrations or when used on sensitive skin, for example in cases of eczema or psoriasis, Vitamin C may cause irritation, redness, or dryness.
Another issue to consider is the proper storage of products containing vitamin C. Due to the instability of ascorbic acid, it is essential that these products are in opaque, tightly closed containers to minimize their exposure to vitamin C. air and light. If vitamin C is oxidized, its color will turn brown or orange, a clear sign that it has lost much of its effectiveness and could even cause more harm than good by generating free radicals in the skin.
It is important not to combine vitamin C with certain ingredients that could cause irritation or cancel its effect. For example, exfoliating products with glycolic acid or retinoids may be too harsh when used simultaneously with vitamin C, which could increase the risk of irritation.
The most important thing discovered by studies is that if a person has adequate levels of vitamin C in the blood, applying creams containing vitamin C does not increase the absorption of vitamin C through the skin. In short, it is better (and cheaper) to take foods containing vitamin C in your diet, including green leafy vegetables and fruits. Consulting a dermatologist before introducing products into your skincare routine is always the best recommendation.
