Getting To The Root Of Why Hair Turns Gray Gray hair is a common sign of aging, but just what causes locks to lose their color isn't well understood. Dr. Gerald Weissmann discusses new research suggesting that hydrogen peroxide build-up in hair follicles may bleach the color from the hair as it leaves the scalp.
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Getting To The Root Of Why Hair Turns Gray

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Getting To The Root Of Why Hair Turns Gray

Getting To The Root Of Why Hair Turns Gray

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This is Science Friday from NPR News. I'm Ira Flatow. When you look in the mirror and you see a couple of gray hairs coming in - maybe up around your temples - do you panic? Do look for the tweezers? The bottle of Grecian formula? The logical part of your brain says that gray hair is just a natural part of getting old, and while you may blame your spouse, your kids, your stressful job for those grays, new research says it's a build up of hydrogen peroxide actually bleaching your hair as it leaves your hair follicle. Joining me now to talk more about this new research is my guest, Dr. Gerald Weissmann, editor-in-chief of the FASEB Journal - that stands for the Federation of American Societies for Experimental Biology. He's a research professor of medicine at NYU. Welcome to the program, Dr. Weissmann.

Dr. GERALD WEISSMANN (Professor Emeritus, Medicine, NYU, Editor-In-Chief, FASEB Journal): Well, it's pleasure to be here.

FLATOW: So, our hair is being bleached like a bleach blonde?

Dr. WEISSMANN: Yes, and more than that. The discovery made by this remarkable group in England and Germany tells us even more than that. We bleach ourselves, and it's part of what's called the free radical theory of graying. And it teaches us also about how we age. So, it's a very important study and pins down on a molecular level.

FLATOW: Walk us through what's happening.

Dr. WEISSMANN: OK, watch. Ordinarily, all of our cells, but especially those in the hair, make just a touch of hydrogen peroxide. And we need it. And we need it because we kill bacteria in this way. It's part of our bacterial defense, ok? So, make a little bit of it. But for some us early, for other of us late, but inexorably all over the body, but especially in the hair, more hydrogen peroxide builds up. As that hydrogen peroxide builds up from let's say, a penny's worth to where it becomes as much as a dollar's worth of hydrogen peroxide - this bleaches the hair follicle the same way blondes do from the outside. And when it does that, that hydrogen peroxide has targets in the hair follicle itself - important enzymes that control the color of hair.

FLATOW: Well, why does it work differently in different people?

Dr. WEISSMANN: For the same reason that people age at different rates. Let's put it this way: If you put a photograph out in the sun, it bleaches, right? That's caused by free radicals induced by sunlight. You put rattan furniture out in the sun, it bleaches by sunlight - free radicals. Different folks, genetically or by environment, have different rates of aging. We're not very good at that - understanding why that happens. But we do know that there's some genetic diseases in which you age very rapidly. It's called progeria.

There are also diseases of the skin in which you become completely white - hair suddenly turns white or turns white for a while. This is a condition called vitiligo. And what happens is that Dr. Wood and Dr. Schallreuter for years had figured out that when you have vitiligo and you have a patch of white hair, that what happens is your hydrogen peroxide builds up enormously. If you get rid of the hydrogen peroxide, the hair returns to its natural color.

FLATOW: And so, of course, everybody's going to what to know what product is going to come out to get rid of their hydrogen peroxide.

Dr. WEISSMANN: Well, It turns out that you don't want to get rid of all of it. That's the problem. You need a kind of peroxide stash, if you will, because you need some of it to get rid of the bugs and you need some for normal physiology. But a lot is very bad. So obviously, people who work on antioxidants and such things as (unintelligible), which can sop up some of the material that is being created by the hydrogen peroxide, has been tried in the dish. But at the moment, we're nowhere there, but boy, as in every other touch of modern medicine, if you have a drug target and you know what the mechanism is, you can eventually find an agent that'll take care of it.

FLATOW: And that's where the research would come in next?

Dr. WEISSMANN: Yes, but this is a true breakthrough, because the exact molecular mechanism of how the hydrogen peroxide hits the follicle cell at the bottom and what it does to melanin, which is the pigment of your hair, what it does to the enzymes that form it has now been worked out on molecular level. And this is a true achievement.

FLATOW: Will these also explain why we have different hair color?

Dr. WEISSMANN: Exactly. Now, watch this: There are two kinds of melanins. There's one called eumelanin, pheomelanin - the name doesn't matter. Blondes and redheads have one kind, and those of us with brown or black hair have another kind. And the exact shade of hair that you have depends on the mixture of those two kinds of pigments. And they differ somewhat in their sensitivity to hydrogen peroxide.

FLATOW: You know, people say that worrying causes gray hair, that, you know, you look at presidents - how they age visibly right there on television - gray hair. Is there any way to explain what seems to be happening there?

Dr. WEISSMANN: People have tried. There's no - there is no direct relationship from my understanding, but now that we know the mechanism of hair graying in general, one can begin to start studying other effects. For example, take someone like Susan Sonntag with a big shock of white hair in the middle of blackā€¦

FLATOW: Right.

Dr. WEISSMANN: That's a striking finding. We can't explain that at the moment. There are genetic causes for something like this, but we're not sure. That's tough to say, but now that you have the mechanism worked out, you can begin to start addressing questions of individual differences, racial differences, and above all, stress. And for example, the way it's been studied very neatly is in the kind of hair that comes back after you lose your hair follicles from chemotherapy. And what happens is that the first hair that comes in is a bit gray, and then gradually the hair regains its color.

FLATOW: So, there's complex stuff going down there?

Dr. WEISSMANN: The hair follicle, in a literally - I won't say nutshell, but in one small, tiny part of our body sums up everything that we need to know about aging. We can study telomeres, DNA - all of the stuff that people who study aging do for a living. And we can use the hair follicle as an exercise in studying the aging of our whole body, and that's, again, what this research has captured.

FLATOW: That's fascinating. Does that mean your growing the follicles in Petri dishes?

Dr. WEISSMANN: You can do it either way. They can be taken apart and studied just as cells and group of cells. The hair follicle can be studied as a kind of tissue culture. But what these investigators did was they took actual hair follicles and by very sophisticated chemical techniques - Raman spectroscopy, et cetera, et cetera - they were able to study the exact chemical reaction that took place in the follicle itself as it came out of the skin.

FLATOW: Wow. Wow. Fascinating. Fascinating. Thank you very much, Dr. Weissmann, for taking time to be with us today.

Dr. WEISSMANN: Not at all and keep your hair.

FLATOW: (Laughing) I'm trying. I'm trying.

(Soundbite of laughter)

Dr. WEISSMANN: We all are.

FLATOW: All right, thanks. Have a good weekend. Dr. Gerald Weissmann is editor-in-chief of the FASEB Journal.

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