Ask the Experts: Why do we go Grey? May 15, 2018 18:13

For many people, grey hair is a fact of life. It’s a sign that we are getting older and that our bodies are going through some changes.

To understand why hair turns grey, we first need to understand why it has colour in the first place. The answer is a special type of cell known as a melanocyte. These produce melanin, the pigment that gives your skin, hair and eyes their distinctive colours.

Melanin comes in two forms, eumelanin (black or brown) and pheomelanin (reddish-yellow). Combinations of these two create the spectrum of eye, hair and skin colours found among humans.

One way to understand how melanocytes determine hair colour is to think of these cells as tiny printers, applying their ink to paper. The paper in this case is our hair strands, formed of keratin, the same protein that makes up our fingernails.

Just as a printer sprays ink onto a sheet of paper to produce an image, melanocytes produce pigments that are embedded into the growing hair strand, providing them with colour. The melanocytes live within the hair follicle, so each hair strand has its own colour-producing printer.

While some people’s melanocytes print a lighter ink combination, such as blonde or red, others have darker colour palletes and so have black or brown colourations.

Now that we understand how hair gets its colour, we can understand why it goes grey.

In hair, grey is not a colouration like any other shade: it is the lack of colouring. The keratin of people with grey hair lacks pigment because their melanocytes have died, revealing the natural white colour of the keratin protein.

Because each hair strand has its own melanocytes, some go grey before others. Exactly what decides which strands go grey first is still unknown. However, age, exposure to chemicals and even the climate can influence how early the melanocytes die.

The strongest influence, however, is written in our genes. The genetic influence on hair colour is so strong that if your parents have grey hair, yours is likely to grey at around the same time as theirs did.

While some women proudly sport a silver mane, many others face the arrival of new grey hairs with dread. Here are a few things to think about...

1. Normal aging is the biggest culprit.

Okay, no surprise here. Dermatologists call this the 50-50-50 rule. "Fifty percent of the population has about 50% grey hair at age 50," says Dr. Anthony Oro, professor of dermatology at Stanford University. And like skin, hair changes its texture with age.

2. Your ethnicity makes a difference.

Caucasians tend to go grey earlier — and redheads earliest of all. Then Asians. Then African-Americans. Scientists haven't figured out why yet.

3. Stress seems to play a role.

"Stress won't cause you to go grey directly," says Dr. Roopal Kundu, associate professor in dermatology at Northwestern University's Feinberg School of Medicine. "But stress is implicated in a lot of skin and hair issues." During an illness, for example, people can shed hair rapidly. And hair you lose after a stressful event — like getting chemotherapy — may grow back a different colour.

4. Your lifestyle makes a difference.

Smoking, for example, stresses your skin and hair. "Low vitamin B12 levels are notorious for causing loss of hair pigment," says Dr. Karthik Krishnamurthy, director of the Dermatology Center's Cosmetic Clinic at Montefiore Medical Center in the Bronx, New York. Try eating foods such as liver and carrots, foods packed with certain vitamins, nutrients and antioxidants may help protect cells against toxins and help prevent heart disease, cancer, and other ailments (and perhaps grey hair!).

5. Hair and its colour are separate things.

Hair stem cells make hair, and pigment-forming stem cells make pigment. Typically they work together, but either can wear out, sometimes prematurely. Researchers are trying to figure out if a medicine, or something you could put in your scalp, could slow the greying process. 

6. Your hair basically bleaches itself.

You may be familiar with hydrogen peroxide as a way to go blonde, but it's also the way we go grey. According to a 2009 study published by the Federation of American Societies for Experimental Biology, hydrogen peroxide naturally occurs in our hair follicles, and as we get older, it builds up. This build-up blocks the production of melanin, a.k.a. our hair's pigment.

7. Your hair doesn't turn grey — it grows that way.

A single hair grows for one to three years, then you shed it — and grow a new one. As you age, your new hairs are more likely to be white. Every time the hair regenerates, you have to re-form these pigment-forming cells, and they wear out.

8. Grey hair isn't more coarse than coloured hair.

Grey hair is actually finer than coloured hair, but it may seem drier because our scalps produce less oil as we get older. Another reason it could seem more rough? "Your hair may also 'feel' coarser if you pull out your first few grey hairs," says Philip Kingsley trichologist Glenn Lyons. "This is because constant pulling-out of hair can distort your follicles, resulting in more crinkly hair."

9. Grey hair can be resistant to colour.

If you opt to colour your hair, your may find that it's more stubborn about taking colour than before you started going grey. Some grey can be resistant to hair colour. If this is true for you, consider dropping down a colour level or using something darker on your roots to deliver even more coverage.