Is That a Gray Hair? The Science Behind Hair Pigmentation

By: Tamar Nicole Soussana  |  December 18, 2019

By Tamar Nicole Soussana, Staff Writer

I recently found a single white hair on the top of my head and asked myself: is this because I’m aging? Is my hair starting the process of graying? Is it some kind of fluke? A genetic predisposition to go gray sooner? There is much to say about going gray and some say it stems from stress. Take any U.S. president for example — it seems as though at the end of their terms, their gray hair increases. Maybe having a stressful job leads to exponential growth of gray hairs. But what exactly is the scientific explanation for gray hairs and what is the correlation to age? 

Each hair on our heads stems from a hair follicle, of which there can be 100,000 just on the scalp. Zooming into a single follicle, hair is grown at the base and pushes its way through the skin, grows, falls out, and begins the process again. These follicles are also responsible for the shape and color of our hair. 

Melanin, which causes pigmentation of the skin, determines our hair color as well, and is stored in follicles. For example, eumelanin leads to black hair and pheomelanin results in red hair. The scientific reason for why hair eventually turns gray is because as follicles on our scalp age, they lose some of their ability to produce melanin, thereby producing less color. The grayer or whiter hair becomes, the more absent it is of color. 

As an overall theme, it seems as though graying hair is just an aspect of aging, and not a sign of one’s mental or physical health. In regards to stress, a possible explanation as to why gray hairs may follow, is a disorder called telogen effluvium. This is a condition triggered by high levels of stress, usually illnesses or childbirth, in which hair can fall out up to three times faster than the normal rate, resulting in temporarily thinner hair. If more hair falls out, follicles are in use more, leading to a possible decrease in pigmentation in a third of the normal time. 

In a study published in Physiological and Biochemical Zoology in 2012, researchers discuss how gray hair seems to be a mark of health — as demonstrated in wild boars — compared to red pigmentation. The reason is because pheomelanin also requires an antioxidant called GSH. The absence of antioxidants leaves free radicals available to damage cells in these animals. Free radicals are extremely unstable molecules, and therefore, potentially dangerous to our bodies. Antioxidants have the unique ability to react with free radicals and stabilize them, while still remaining stable themselves.

To prove their hypothesis, the researchers tested the oxidative stress (imbalance between free radicals and antioxidants) in wild boards with gray and red hair. The results showed that increased pheomelanin followed decreased GSH. Therefore, in wild boars with red hair, there is more potential for free radical damage. 

It is well known that science is usually very specific to certain environments or species. For humans, our gray hair mostly reflects the amount of melanocytes (cells that produce pigment) in our hair follicles and does not determine increased health or antioxidant availability. 

At the end of the day, hair turning gray is most likely due to genetics, which determines how much pigmentation our follicles can produce along with what color and shape our hair is. Finding some gray hairs doesn’t immediately mean you are getting too old, or your life is too stressful, but is most reasonably explained by one’s genetics — just ask your parents when they found their first gray! 

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