Why Hair Turns Gray Hair grows in a follicle, a bulb-like tube on your scalp. The average head has 100,000 to 150,000 follicles, each operating independently from the others. Hair in its basic, unpigmented state is white. It gets its color from melanin, a pigment that also determines skin color. Two types of melanin, eumelanin (dark brown or black) and phaeomelanin (reddish yellow), combine to make all the hair colors. One hypothesis for why hair goes gray is that aging slows or stops the hair from accessing the melanin, so it comes out gray, silver, or white instead. New research reveals that graying may be from a build-up of hydrogen peroxide in the hair cell, which causes the hair to bleach itself on the inside. Cells naturally have a small amount of hydrogen peroxide in them, but it’s kept in check by an enzyme called catalase, which converts the hydrogen peroxide to oxygen and water. As we age, the body produces less catalase, so the hydrogen peroxide builds up and blocks “t...
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