When it comes to antioxidant skincare ingredients, the majority of dermatologists gives high marks to Vitamin C. Recognized as one of the skincare’s greatest players, vitamin C is one of the most frequent choices among young women and it has the advantage of having a high safety profile which means a prolonged use without experiencing significant adverse reactions (1).
Although normal young skin contains high concentrations of vitamin C, these levels tend to decrease as we age, reducing the endogenous antioxidant defenses of the skin (2). Considering that the body lacks the enzyme required for its synthesis, vitamin C supplementation is a smart strategy to try to maintain your skin healthy.
Vitamin C has been postulated to provide significant protection against UV light and other environmental insults such as pollution and smoking, by neutralizing the reactive oxygen species produced during the exposure (3). Due to its antioxidant activity, vitamin C acts as a free radical scavenger, donating its electrons to the oxygen species and making them less reactive.
This ingredient may be more interesting than just a shield. With its continued use, it has the ability to increase collagen levels, acting as a cofactor for the molecules involved in its synthesis and downregulating the enzymes that degrade it (4). Thus, vitamin C can participate in contrasting the signs of photo-aging, by reducing fine lines and wrinkles and improving firmness.
Furthermore, studies have shown that vitamin C has anti-inflammatory effects, helping to reduce symptoms of some inflammatory conditions such as acne, atopic dermatitis and psoriasis, and creating a more even complexion (2). In addition to minimizing redness, vitamin C helps fade dark spots and hyperpigmentation, as it inhibits the action of tyrosinase, the enzyme responsible for the pigment formation.
Researchers have demonstrated that two key components influence the efficacy of vitamin C skincare products: formulation and packaging.
The active form of vitamin C (L- ascorbic acid) is a highly unstable molecule and needs to be formulated at specific conditions to ensure its efficacy. Formulations with a low pH of approximately 3.5 have shown to greatly aid its penetration into the skin and to improve its stability (5).
Vitamin C absorption has demonstrated to be proportional to its concentration with maximum results at 20%. Higher concentrations may lead to irritation without increasing vitamin C efficacy (5). Furthermore, studies have shown that vitamin C works best in team with vitamin E and ferulic acid, increasing its efficacy four-fold when combined with vitamin E and eight-fold when ferulic acid is added to the combination (6).
Yet, when vitamin C is exposed to light or air it gets oxidized to dehydroascorbic acid (DHAA), losing its antioxidant properties and giving a yellow color to the formulation (1). Therefore, opaque and airtight bottles are preferred to help ensure the ingredients remain unaltered.
Vitamin C in skincare and dermatology seems to be too good to be true, and indeed this is a bias that can be attributed to its safety profile and to the consequent thought that if it does little or no harm then it is worthwhile to use because its risks must surely be outweighed by its benefits. Yet, the extent of its beneficial effects is really unknown, because the scientific data that back up the claims is scarce and derives from small studies. The lack of solid data on vitamin C is paradoxical, if we think that the first true clinical trial ever performed was performed on citrus fruits in 1781 by James Lind to demonstrate that this molecule prevents scurvy (7). As a scientist, I believe that vitamin C is a promising molecule, but it should be tested in large informative trials to really understand its potential on skin.
1. Telang P. S. Vitamin C in dermatology. Indian dermatology online journal. 2013. 4(2), 143–146.
2. Pullar JM., et al. The Roles of Vitamin C in Skin Health. Nutrients. 2017. 9(8):866.
3. Duarte TL., et al. Gene expression profiling reveals new protective roles for vitamin C in human skin cells. Free Radic Biol Med. 2009. 46(1):78‐87.
4. Farris PK. Topical vitamin C: a useful agent for treating photoaging and other dermatologic conditions. Dermatol Surg. 2005. 31(7 Pt 2):814‐818.
5. Al-Niaimi, F., et al. Topical Vitamin C and the Skin: Mechanisms of Action and Clinical Applications. The Journal of clinical and aesthetic dermatology. 2017. 10(7), 14–17.
6. Lin FH, Lin JY, Gupta RD, et al. Ferulic acid stabilizes a solution of vitamins C and E and doubles its photoprotection of skin. J Invest Dermatol. 2005. 125(4):826‐832.
7. Hughes R. E. James Lind and the cure of scurvy: an experimental approach. Medical history, 1975. 19(4), 342–351.