Can you prevent or reverse grey hair? Here's what scientists have untangled so far

It’s a question that has perplexed scientists for decades.

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For something so universal, greying remains oddly mysterious.

Each strand of hair starts out nearly translucent, and its colour is determined by melanin, essentially pigment dust. If it’s packed densely, you end up with dark hair. Leave only a few black and brown specks, and it appears blonde.

Over time, the pigment-producing cells in each hair follicle tend to slow or shut down, turning hair gray, said Desmond Tobin, director of the Charles Institute of Dermatology at University College Dublin in Ireland. These strands tend to be stiffer and harder to control, growing 10 per cent faster than pigmented hairs. Some people embrace them as a part of ageing; others see them as a nuisance to be dyed, plucked or hidden.

But scientists aren’t sure what sets greying in motion or how much control we have over it. People can begin greying in their 20s or keep their natural colour into their 80s. Although the process seems to be largely irreversible, researchers are finding that colour can sometimes return – in patches and in darker roots.

For now, there’s no silver bullet to prevent or reverse greying, but experts are trying to untangle the issue and develop solutions.

WHAT DO SCIENTISTS KNOW SO FAR?

Our hair doesn’t grey all at once, which is why you might notice stray silver strands and then experience a salt-and-pepper phase. Some hairs can even get lighter and darker again.

Each follicle is an independent unit, containing its own pigment-producing cells called melanocytes and a reservoir of replacement stem cells. As we age, these cells naturally accrue damage, like from stress or cellular wear and tear.

Hair greying usually starts when melanocytes in a particular follicle get compromised, but it becomes permanent when the stem cell reservoir is exhausted, said Emi Nishimura, a professor of ageing and regeneration at the University of Tokyo. There’s research to suggest that, if the first process happens without the second, grey hair can be reversed.

In a small 2021 study, scientists collected hairs from people who had started greying and found distinct dark and white bands. Because hair grows roughly a centimetre each month, these bands offered a timeline, so researchers asked participants to chart their stressful experiences over the past year. Periods of higher stress lined up with lighter bands, and lower-stress periods corresponded with bands where colour returned. In other words, dialling down stress levels appeared to reverse or slow hair greying.

Some people with grey hair have also spontaneously repigmented in patches after getting certain types of chemotherapy, radiation or immunotherapy. Experts suspect that, in these rare cases, the cancer treatments might coax dormant stem cells to rebuild functional melanocytes.

This research suggests that hair greying isn’t a completely linear process and that there’s a “window of opportunity” where pigment loss can be reversed, said Dr Ralf Paus, a dermatologist at the University of Miami. How long that window stays open – and what could safely reawaken stem cells – is still unclear.

WHAT CAN YOU DO ABOUT GREY HAIR?

Much of hair greying is genetic, said DrJessica Shiu, a dermatologist at the University of California Irvine Health, so your parents and grandparents offer the best insight. Researchers have also found that greying usually starts in the mid-30s for white people, late 30s for Asian people and mid-40s for Black people.

But lifestyle choices might also make a difference. The strongest evidence points to quitting cigarettes and reducing your stress levels. Getting enough sleep and eating a healthy diet – with lots of antioxidants – might also limit the damage to your pigment cells, Dr Shiu said, although the evidence is more indirect.

Premature hair greying has also been linked to low levels of iron and Vitamin B12, but in the United States, deficiencies severe enough to affect hair pigmentation are rare, Dr Tobin said. And there’s no evidence that supplements help with greying.

Be cautious about anti-grey supplements overall, Dr Shiu said, since they’re often sold on promise not proof. Even if these supplements contain something helpful, there’s no evidence that taking a pill or applying a cream reaches the pigment cells deep inside hair follicles.

Although there are no medical treatments for grey hair, talk to your doctor about sudden or early greying, because a small share of cases are linked to prescription medications or diseases – and might be reversible. For example, some antiseizure medications, antimalarials, oral retinoids and muscle spasticity drugs have been tied to hair greying. Many cancer drugs also induce pigment loss, despite the rare cases of repigmentation.

Doctors can also distinguish between age-related greying and conditions that cause it. Thyroid and other hormonal disorders have been linked to early graying, as have autoimmune conditions that target hair follicles, like vitiligo and alopecia areata. Treatment can limit further pigment loss and sometimes allow colour to return.

For most people, there’s not much you can do to prevent grey hair, but stacking small changes can help. “It’s not anything crazy – it’s just living a healthy lifestyle,” Dr Shiu said.

By Simar Bajaj © The New York Times Company

The article originally appeared in The New York Times.

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