Why Hair Turns Gray

It’s a natural process, but stress and smoking don’t help

Unless you dye, your hair eventually loses its color, usually beginning in your 30s or 40s. Though going gray is natural, many people dread it because of society’s notions about aging. Here’s what researchers know about how and why graying hair happens.

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What gives hair its natural color?

Melanin, the brown/black or yellow/red pigment that tints skin and eyes, also dictates your hair’s hue. Like paint-mixing, the amount and combination of melanin determines hair color.

Why does hair have color?

Scientists aren’t sure. The trait may have evolved partly to help pre-humans stand out from each other and attract mates, and to help regulate body temperature by absorbing or reflecting sunlight.

Why does hair turn gray?

Gray hair is really hair with reduced melanin, while white hair completely lacks it. That’s partly because of a gradual decline in the number of stem cells that mature to become melanin-producing cells. Scientists aren’t sure why. The cells may wear out, become damaged, or lose the support systems meant to keep them working. Genes are also a factor, since they help control melanin production.

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Can anything prevent hair from graying?

For now, no. Scientists experimenting with mice recently showed that three specific genes can help maintain stable numbers of melanin-producing cells. By manipulating the genes, the researchers prevented or reduced gray hair in the mice. But no product based on the research is currently available.

Can stress or fear cause hair to suddenly lose color?

Probably not. Historical accounts claim jailed British statesman Sir Thomas More and French queen Marie Antoinette went white overnight while awaiting execution. But dermatologists say the likely explanation is either that their vegetable- or mineral-based hair dye washed away, or that they had alopecia areata, an autoimmune disease that can be triggered by stress and causes pigmented hair to rapidly fall out but doesn’t affect white hairs, creating the illusion of a sudden color change.

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Can stress cause gradual, long-term hair graying?

Maybe. Researchers examining gray hair have found evidence of “free radicals” — damaging chemicals caused by stress, smoking, inflammation or radiation exposure, among other things — and propose that they’re responsible for destroying pigment-producing melanocyte stem cells. But there’s no conclusive proof.

Can smoking cause premature graying?

There’s definitely a link. A 2013 study found that smokers on average went gray three years earlier than non-smokers. Scientists suspect that smoking causes chemical changes that damage the body’s melanin-producing cells.

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