Photodamage of the skin: protection and reversal with topical antioxidants.
Controversy exists as to whether topical antioxidants can be effective in protecting against and reversing photodamage to the skin. Topical vitamins C and E, as well as topical selenium, protect skin against sunburn, suntan and skin cancer and also reverse the mottled pigmentation and wrinkles of photoageing. However, only certain forms of these labile antioxidants are stable and active after percutaneous absorption. For effective topical application, vitamin C must be non-esterified, acidic and optimally at 20% concentration; vitamin E must be the non-esterified isomer d-alpha-tocopherol at 2-5% concentration. Selenium is only percutaneously absorbed and active when applied topically as l-selenomethionine, optimally at 0.02-0.05%. There are two great advantages in applying an active formulation of topical antioxidants to the skin. First, the skin attains far higher levels of each antioxidant than can be achieved by only taking these vitamins orally. The level of vitamin C attained in the skin by topical application is 20-40 times that achievable with oral vitamin C. With topical application, the concentration of vitamin E in the skin increases by a factor of 10.6 and selenium by a factor of 1.7. Second, topical application arms the skin with a reservoir of antioxidants that cannot be washed or rubbed off, a protection which stays in the skin for several days after application.
Burke
K E
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heather.nolan@gs.com