Our skin consists of two main layers: the dermis and epidermis. The dermis is the inner layer of skin that contains nerve fibers, fat cells, blood vessels, sweat and oil glands, and hair follicles. The dermis also contains collagen and elastin, two proteins that are responsible for the structure and elasticity of the skin itself. These proteins are subject to the process of aging. The sweat and oil glands in the dermis protect the outer layer of skin with a thin coating of oil and perspiration.
Scientists now believe that the free radical theory of disease also applies to the aging of the skin. Free radicals are unstable small molecules generated by an oxygen environment which require stabilization by the body's antioxidant system. Free radicals occur throughout every cell in our body simply by virtue of the fact that oxygen is our principal metabolic fuel. Strong sunlight readily generates free radicals in the skin. Our hands, face, neck, and arms are the areas usually chronically exposed to light. These parts of the body, particularly the face, are where aging of the skin shows up.
The skin protein collagen is particularly susceptible to free radical damage, and when this damage occurs, it causes the collagen protein molecules to break down and then link back up again in a different way; this is known as cross-linking. Collagen cross-linking causes the normally mobile collagen to become stiff and less mobile.
Science clearly substantiates the role that free radicals play in causing skin aging and the fact that topically applied antioxidants confer significant protection and can even partially reverse some aspects of skin aging. Indeed, various animal and human studies have proven that low molecular weight antioxidants, especially vitamins C and E, as well as alpha-lipoic acid exert protective effects against free radical damage (oxidative stress) (Podda et al. 2001).
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