We ask a lot of questions about our diet.

What's the right way to treat a chronic illness, fight off a virus, lose weight?

The problem is we get a lot of different answers.

Well, I'm here to help.

Welcome to the Nutrition Facts podcast.

I'm your host, Dr. Michael Greger.

Today we look at why hair turns gray.

What's the role of genetics and what we can do about it?

The graying of hair is one of the most obvious signs of aging.

It's also known by a technical term that I'd never heard of, Canities.

The first time I saw the word I misread it, wondering what gray hair

had to do with dentistry. Evidently, gray hair isn't really white, but a pale yellowish tinge

of the constitutive keratin protein, but like polar bears, it just looks white, by the way,

light reflects off of it. Why is hair pigmented in the first place?

Some suggest it may be for detoxification as natural toxins, like heavy metals,

bind to the pigment melanin to be extreated from the body through hair outgrowth.

That's why you can estimate the amount of fish consumption from the mercury content of children's

hair clippings.

Why analysis of hair mercury may be warranted before pregnancy in women who eat a lot of fish,

and why the levels of mercury in the hair of those eating plant-based diets were found to be

up to ten times lower than those who just occasionally ate fish. Within three months of switching

to a plant-based diet, the levels of mercury, lead, and cadmium growing out in your hair

...