What Causes Hair to Turn Gray?

Photo credit: Bigstockphoto
Photo credit: Bigstockphoto

Is your hair turning gray? Those first gray hairs are a subtle reminder of the passage of time, although some people experience premature gray hair as early as their late twenties. Although we think of gray hair as being a natural part of the aging process, there are lifestyle factors and medical conditions that can speed up how quickly those gray hairs appear.

What Causes Hair to Turn Gray?

Hair turns gray when melanin production declines. Melanin is the pigment, produced by cells called melanocytes, that gives hair its color. At first the melanocytes simply produce less melanin, but, over time, they also decline in number. This occurs as a natural part of aging, but when it happens is mostly determined by genetics. If your parents turned gray early in life, there’s a good chance you will too. Men also turn gray several years before women on average.

Hair Turning Gray: Can You Prevent Gray Hair?

When hair turns gray is genetically determined, and there’s not a lot you can do to prevent gray hair. There’s some thought that free radical damage contributes to premature graying. If this is true, eating an antioxidant-rich diet could delay the process although this hasn’t been studied. One thing you can do is quit smoking. A British study found that smokers are more likely to turn gray prematurely.

Premature Gray Hair: Is It a Sign of Bad Health?

Graying hair can occasionally be a sign of a medical problem. Some conditions associated with premature gray hair are thyroid disease and some autoimmune disorders. One example is vitiligo, an autoimmune disease that causes premature destruction of melanin-producing melanocytes. This leads to gray hair and white patches on the skin. Deficiency of vitamin B12 also suppresses melanin production and leads to premature graying.

What about stress? Contrary to popular belief, there’s little evidence that stress contributes to the hair turning gray or premature gray hair.

The Bottom Line?

You don’t have a lot of control over when your hair turns gray. Your genes determine that, but you may delay it slightly by not smoking and eating an antioxidant-rich diet. If you suddenly start graying, especially if you’re under the age of thirty, see your doctor to rule out medical causes.


Intelihealth.com. “The Science of Gray Hair”
Merck Manual. Eighteenth edition. 2006.

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