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SUMMARY POINTS
What’s Important?
Antioxidants protect against the ravages of free radicals by reducing and neutralizing them.
Antioxidants may be particularly useful in UVA-induced skin alterations that are believed to be determined, in large part, by oxidative processes.
Topical antioxidants are currently marketed for the prevention of aging and UV-mediated skin damage as well as the treatment of wrinkles and erythema due to inflammation, such as that induced by laser resurfacing.
The free radical theory of aging explains why antioxidants are thought to prevent wrinkles, but this theory does not justify the use of antioxidants to treat wrinkles that are already present.
What’s New?
New antioxidants are being introduced into the market frequently.
Using combinations of antioxidant types is preferred rather than one antioxidant.
Antioxidants should be included in diet, beverages, and supplements in addition to topical skincare products.
What’s Coming?
New methods are needed to quantify antioxidant strength so that efficacy between types can be compared. Current antioxidant quantitative measurements such as the ORAC value pertain to foods, not topical products.
Antioxidants are being evaluated to protect mitochondria and other cellular components.
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THE FREE RADICAL THEORY OF AGING
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The free radical theory of aging, proposed by Harman in 1956,1 is one of the most widely accepted theories to explain the causes of aging.2 Free radicals, also known as reactive oxygen species (ROS), are compounds formed when oxygen molecules combine with other molecules yielding an odd number of electrons. An oxygen molecule with paired electrons is stable; however, oxygen with an unpaired electron is “reactive” because it seeks and seizes electrons from vital components leaving them damaged.3 DNA, cytoskeletal elements, cellular proteins, and cellular membranes may all be adversely affected by activated oxygen species.4 ROS have not only been implicated in the overall aging process,5 but are believed to be involved cutaneously in causing photoaging, carcinogenesis, and inflammation. It is known that ultraviolet (UV)-induced damage to the skin is in part mediated by reactive oxygen intermediates.6 If antioxidants can absorb some of the resulting free radicals, they may be able to mitigate UV-induced damage to the skin. Free radicals may also lead to inflammation, which is believed to play a role in skin aging.6 Lipid peroxidation, another sequela of free radical production, causes harm to cell membranes and can lead to skin aging, atherosclerosis, and other signs of aging. Free radicals are also thought to contribute to the development of skin cancer. There are multiple studies in the literature describing the role of free radicals and skin cancer. The exact mechanisms for all of the detrimental effects of free radicals have not been completely elucidated, however.
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Free radicals also play an important role in intrinsic and extrinsic skin aging. They are formed naturally through normal human metabolism but can be produced via exogenous factors, such as UV exposure, air pollution, smoking, radiation, alcohol ...