Melanin: Aging of the Skin and Skin Cancer by Diana Clarke

Melanin: Aging of the Skin and Skin Cancer

by Diana Clarke

http://yourskinandsun.com

"Ultraviolet (UV) radiation is responsible for 90% of the visible signs of aging on the skin of whites," says Dr. Michael J. Martin, former Assistant Clinical Professor in the Dept. of Epidemiology and Biostatistics at University of California, San Francisco.

Blacks' skin, however, ages much slower.

Why are most dark-skinned blacks protected from harmful UV rays? Because compared to whites, blacks possess more melanin, the pigment that gives skin its color.

Melanin

Melanin offers protection against UV rays for blacks and other dark-skinned people. Conversely, fair-skinned people are much less protected and more susceptible to skin cancer. Furthermore, albinos' skin offers no protection.

Although blacks' skin produces more melanin than whites', all skin has the same number of melanocytes, the cells that manufacture the melanin.

Melanocytes manufacture melanin from an amino acid, tyrosin, with the help of an enzyme, tyrosinase. In the bottom layer of the epidermis above the dermis, UV light stimulates the production of melanin in the form of insoluble melanosomes. These surround the epidermal cells, which move up to the surface of the skin. The result is a tan.

Blacks' skin produce more melanin, even in the absence of sunlight, and their type of melanin, eumelanin, is more effective at blocking solar rays. However, white skin produces melanin only in the presence of sunlight and after the UV rays have penetrated the lower portion of the epidermis and have caused skin damage.

"Melanin also functions as an excellent free radical scavenger. It affects the delicately designed lipids that hold moisture in the stratum corneum (the outermost layer of the epidermis). If the skin loses its moisture, it becomes rigid and cracks," says Sergio Nacht, PhD., Senior Vice-President of Enhanced Derm Technologies, Inc. in Redwood City.

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BIO:

Diana Clarke is the editor of the Sun and Your Skin at http://yourskinandsun.com. She is a California credentialed teacher, freelance writer, and president of her own company, Clarke Communications and Technology. Her sun protection articles have appeared in publications, such as the San Jose Mercury News, Saratoga News and a high school health magazine, Listen Magazine.

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