Ascorbic acid is a water soluble alpha hydroxy acid (AHA) that functions as an antioxidant and a required chemical for several metabolic reactions. It occurs naturally in plants particularly in fruits and some animals are able to synthesize this vitamin. Ascorbic acid can also be produced in large scale using a two-step fermentation process of glucose. This vitamin is best known for its ability to prevent and treat scurvy.
Topical ascorbic acid accelerates the healing of wounds as it aids in stabilizing and generation of collagen. This vitamin stimulates collagen synthesis, production of stable collagen and triggers the production of enzymes that is necessary for the cross linking of collagen molecule which in turn gives better tissue strength.
Topical vitamin C performs three different functions in skin metabolism: as an antioxidant, as an inhibitor of melanin, and as a stimulator of collagen synthesis. As an antioxidant, vitamin C prevents or suppresses the development of skin cancer caused by UVA and UVB exposure. As a melanin inhibitor, vitamin C helps to lighten the skin. And by stimulating collagen synthesis, vitamin C accelerates skin firming and helps to prevent fine lines.
Applied topically, l-ascorbic acid:
Improves the appearance of skin by reducing fine lines and wrinkles and protects and lessens the effects of sunburns. It also protects the skin from free-radical attack, and prevents skin cell damage due to ultraviolet radiation Once L-Ascorbic acid penetrates the skin, it stays there for up to 72 hours. This means that a properly formulated topical vitamin-C product can have a long lasting effect in the skin.
Fast acting, results can be seen in just a few days or weeks of use. Improvement in skin texture and skin tone is easily noticeable after several days of use. Depressed scars may take several months to be normalized.
* L-ascorbic acid is highly unstable when exposed to heat, light and air losing its beneficial effects on skin cells. The potency of topical L-ascorbic acid degrades because of its conversion into dehydroascorbic acid. Dehydroascorbic acid is the inactive form of vitamin-C. Most products on the market contain L-Ascorbic acid in aqueous solution and they have very very poor stability. They degrade in just a few days. Pure and active L-Ascorbic solution is clear in color and turns yellow as it is degraded into Dehydroascorbic Acid. Further degradation would turn the color of ascorbic acid from yellow to dark brown. Some manufacturers put food yellow food colorings into their product so that you will never be able know how inactive and degraded are their product.
To be effective, topical ascorbic acid must be formulated at an acidic pH which is preferrably pH 3.5 or less. The skin penetration ability of topical ascorbic acid is dependent on its acidity. The more acidic the formulation the better is the skin penetration but skin irritation also increases. The concentration of topical ascorbic acid should be at least 10% to be effective and 20% for optimum skin absorption. A 20% concentration ascorbic acid solution is irritating enough that it may cause temporary redness and moderate stinging sensation. Studies have shown that Magnesium Ascorbyl Phosphate and Ascorbyl Palmitate is not as effective as L-Ascorbic acid solutions. Some manufucturers use these "alternative" forms of topical vitamin-C because they are more stable compared to L-ascorbic acid solutions but their effectiveness is questionable.
* Studies have shown that ascorbic acid derivatives such as Magnesium Ascrobyl Phosphate and Ascorbyl Palmitate did not increase the levels of ascorbic acid in the skin.
(Source: Topical L-ascorbic Acid: Percutaneous Absorption Studies Pinnell SR, Yang H, Omar M, et al Dermatol Surg. 2001;27:137-142)
* Application of 5% vitamin C cream resulted in a significant improvement in both fine and coarse wrinkles. Ultrastructural evidence of elastic-tissue repair confirmed the clinical improvement in the vitamin C group. The treatment was well-tolerated. (Source: Topical vitamin C for photoaged skin,Townsend Letter for Doctors and Patients, Dec, 2005 by Alan R. Gaby)
* "Vitamin C has the potential to enhance the density of dermal papillae, perhaps through the mechanism of angiogenesis. Topical vitamin C may have therapeutical effects for partial corrections of the regressive structural changes associated with the aging process". (Source: Topically applied vitamin C increases the density of dermal papillae in aged human skin, Kirsten Sauermann, Sören Jaspers, Urte Koop, and Horst Wenck)
Sorg O, Antille C, Saurat JH. Retinoids, other topical vitamins, and antioxidants. Photoaging. Marcel Dekker, 2004: 89-115.
Chiu A, Kimball AB. Topical vitamins, minerals and botanical ingredients as modulators of environmental and chronological skin damage. Br J Dermatol 2003; 149(4): 681-691.
Lupo MP. Antioxidants and vitamins in cosmetics. Clinics in Dermatology 2001; 19:467-473.
Colven RM, Pinnell SR. Topical vitamin C in aging. Clin Dermatol 1996; 14:227-234.
VITAMIN C By Dr. Des Fernandes Copyright© Environ Skin Care (Pty) Ltd. 2006.
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