It is somewhat ironic that in a time of economic crisis and two wars, the front page of the New York Times today (Thursday, March 5, 2009) features an article by Helene Cooper (cited below) on the increase in the amount of gray hair on the president’s head after only 44 days in office.
To be fair, one of her main points is that presidents tend to get grayer much quicker than the regular population, presumably owing to the greater stress they experience on the job.
Perhaps serendipitously, a major review of the causes of graying hair, which introduces important new experimental data, appeared only last week, in the FASEB Journal. (cited below as Wood et al.)
There has been a long list of theories about the causes of graying hair, but more and more consensus has been building up, largely based on on long-range population genetic studies and on some experimental data.
Graying is, by the way, a phenomenon that humans share with many mammals, who often have lightening or whitening and graying of their fur with increasing age.
Indeed, lab mice are the traditional experimental animals of choice for the study of graying hair. But as we will see shortly, this is changing.
Graying Owing To Less Efficient & Dying Off Pigment Cells
The most prominent explanation at the cellular level for graying hair, is a breakdown in one of the two major cell types that contribute to hair growth.
These cell categories are the keratinocytes, and the melanocytes. They live together in the follicle, the bulbous structure at the base of a hair, located in deepest layer of the skin.
Basically, melanocytes (sometimes called pigment cells) provide the color through leaking it into the keratinocytes. Through their own physiologically normal, planned cellular death, the now tinted keratinocytes provide the protein keratin whose build up after their deaths, results in the growth of a shaft of hair.
Despite what one hears on TV ads about making one’s hair “come alive” or get “more lively,” all hair shafts , are, in fact, dead and incapable of reanimation. Only the cells within the follicle are alive.
The effects of various shampoos, crème rinses, and mousses, works by softening the inanimate fiber much as water might soften straw or fabric softener relaxes cotton, wool or polyester fibers in cloth. Damaged hair is generally the result of applying the wrong substances, too much of the right substances, or too much heat or sun that damages the underlying skin or reduces the overall level of moisture in the scalp.
The particular color (and curl or lack of it), of one’s hair (blond, red, brunette) is driven by underlying genetics, but the intensity of that color is built on the productivity of the melanaocytes in making melanin, and on the amount they manage to diffuse into keratinocytes.
The standing theory was that the melanocytes first start producing less melanin as they age, and then, the melanocytes themselves die out.
The keratinocytes keep making keratin, and through their dying, leave the keratin to grow into hair. But with less, and eventually without any, melanin, soon the hair appears grey or white.
Turning Gray “Overnight”
What causes a sometimes noticed or reported sudden increase in the amount of gray hair is not so much the simultaneous deaths of all the melanocytes, but rather, an increase in the number of hair strands lost each day, that adversely favors the older hair strands, in a kind of statistical trend.
The oldest hairs, which grew when there was more melanin production, are typically the most strongly colored hairs, and they fall out, naturally enough, first.
Some white or gray strands also fall out, so that initially, the balance of dark to gray or white seems to be only slowly tilting towards the gray or white.
But according to traditional theory, eventually more follicles have fewer or less productive melanocytes, and the hair they keep on growing turns grayer or whiter.
This means that with every hair shed, the replacement hair shaft will be more likely to be gray or white, because more of the purely darker hairs will not be replaced.
The end result is that there are fewer darker hairs to mask the presence of the gray or white ones, which now stand out much more starkly.
The number of hairs lost daily is well known to be under the influence of not only genetics, and aging, but also nutrition, certain medicines and diseases, chemotherapeutic drugs, and fairly often, physical or mental stress.
Accelerating hair loss simply speeds up the shedding of hairs of all colors, with the remaining hairs and succeeding hairs more likely to be gray or whiter sooner.
Hydrogen Peroxide: Good for Making Some People Temporarily Blonde,
But An Aggressive Co-Factor in Turning Everyone’s Hair Gray or White
While there are many nuanced innovations that could be reported about the Wood et al paper, two are particularly notable.
The first is their improvements on a system for viably culturing human follicle cells in what amounts to Petri dishes. (The source of the hair follicles was skin removed during facelifts done during cosmetic surgery.) This allowed for fewer discrepancies and less tentativeness in drawing conclusions formerly caused by the use of lab animals.
The second was a system for precisely tracking the amount of certain proteins and metabolic residues in hair follicles, and in the hairs themselves, using Fourier-Transform Raman spectroscopy.
Their ultimate conclusion was that a significant build up of hydrogen peroxide and metabolic complexes ultimately disabled the production of the melanin through poisoning of intermediate steps towards its production. Most notably it interfered with tyrosine-based precursors of melanin.
It was shown that gray and white hairs had massive amounts of the suspect biochemicals, and that darkly pigmented hairs had virtually none at all.
In a sense, the destruction of melanin-making is caused by the melanocyte’s and keratinocyte’s declining abilities to clean up the waste products of the making and incorporation of melanin.
The hope of this new research is not for hair care products that dye the dead hair shaft but for hair and scalp treatments that help break up the unwanted buildup of hydrogen peroxide and scavenge incomplete metabolic byproducts, so that melanin production can continue in the living melanocytes.
In the meantime, try hard not to worry about the rate at which your hair is going gray or white. It will only increase hair loss, and you now know that is ultimately not a good thing if going gray or white bothers you.
Besides, you will only court derision from people proud of their new hair color, or from people who have gone bald, and wonder why you consider yourself so badly off.
Tony Stankus tstankus@uark.edu Life Sciences Librarian & Professor
University of Arkansas Libraries MULN 223 E
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Arck, P. C., Overall, R., Spatz, K., Liezman, C., Handjiski, B., Klapp, B. F., et al. (2006). Towards a "free radical theory of graying": Melanocyte apoptosis in the aging human hair follicle is an indicator of oxidative stress induced tissue damage. The FASEB Journal, 20(9), 1567-1569.
Choi, Y. J., Yoon, T. J., & Lee, Y. H. (2008). Changing expression of the genes related to human hair graying. European Journal of Dermatology : EJD, 18(4), 397-399.
Cooper, H. (2009). 44 days in the White House, and the hair? Grayer already. New York Times, 158, (54,605), A1, A19.
Emerit, I., Filipe, P., Freitas, J., & Vassy, J. (2004). Protective effect of superoxide dismutase against hair graying in a mouse model. Photochemistry and Photobiology, 80(3), 579-582.
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Saha, B., Singh, S. K., Mallick, S., Bera, R., Datta, P. K., Mandal, M., et al. (2009). Sphingolipid-mediated restoration of mitf expression and repigmentation in vivo in a mouse model of hair graying. Pigment Cell & Melanoma Research,
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Wood, J. M., Decker, H., Hartmann, H., Chavan, B., Rokos, H., Spencer, J. D., et al. (2009). Senile hair graying: H2O2-mediated oxidative stress affects human hair color by blunting methionine sulfoxide repair. The FASEB Journal , epub ahead of print, made available online February 23, 2009.
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Posted by: super real | November 23, 2013 at 11:52 AM
Wow, I really didn't notice that President Obama’s has a graying hair!
-Peter
Posted by: skin care answers | January 27, 2010 at 05:33 AM