Vitamin C

Vitamin C is a major water soluble antioxidant that plays a vital role in photoprotection as well as in collagen synthesis. The body reservoir of vitamin C decreases with age, and habits such as smoking decrease reserves even more. Vitamin C is not produced in the body and must be consumed entirely through diet and oral supplementation. Likewise, in the skin where vitamin C plays a vital role in photoprotection and aging, it must be topically supplemented since, unlike vitamin E, it is not produced in the skin.

The role of vitamin C in photoprotection has been demonstrated by the dramatic reduction of vitamin C in skin following UV radiation. In addition, a combination of both vitamins E and C work synergistically to enhance their photoprotective effects. This reinforces the benefit derived from enhancing photoprotection by combining antioxidants with sun-protection products [17, 18].

Vitamin C is an essential cofactor for the hydroxylation of proline and lysine, a necessary step in collagen synthesis. In fact, fibroblasts in cell culture will selectively secrete collagen when vitamin C is added in a dose-dependent fashion. Its role in collagen synthesis is probably responsible for the wrinkle-reducing and skin-firming effects that vitamin C has on aged skin [19, 20, 21]. Vitamin C also appears to reduce signs of photoaging. In addition, topical vitamin C increases levels of tissue inhibitors of collagen-degrading matrix metalloproteinase1 (MMP_-1) [22].


The ability of topical vitamin C to reduce hyperpigmentation has been demonstrated and has found its way into various skin-lightening products.Vitamin C is able to lighten hyperpigmented skin through the inhibition of the enzyme tyrosinase [23].

Many forms of vitamin C have been used in various topical formulations in efforts to stabilize this highly unstable molecule.However, any form of vitamin C that is applied to the skin must convert to the L-ascorbic acid form in order to be recognized by the body and deliver a benefit. Stabilizing vitamin C was an impossibility until 1988 when Dr. Sheldon Pinnell from Duke University, one of the pioneers of topical vitamin C research, was able to stabilize ascorbic acid in solution. The same study also showed the presence of ascorbic acid in the skin days after the application with an increase in the level of collagen as well, proving the penetration and benefit of the topically applied vitamin C [24, 25].

There are so many different vitamin C variations used in skin care that rather than naming each one, the process can be simplified by dividing them in either water soluble (L-ascorbic acid and magnesium or sodium ascorbyl phosphate), fat-soluble esters (ascorbyl palmitate, ascorbyl tetra-isopalmitate), or anhydrous systems. Unfortunately, the long-term stability of topical vitamin C preparations remains a concern. The most stable vitamin C preparations remain anhydrous or completely water free.