How greying hair might actually be defending you against cancer

While most people try everything possible to hide or reverse their greying hair, a new study suggests that those silver strands might actually be doing your body some good.

Researchers have found that the process behind hair turning grey could be part of the body’s natural defence mechanism against cancer.

The study, published in Nature Cell Biology, examined how stem cells in hair follicles react when their DNA gets damaged, and uncovered an unexpected link between grey hair and melanoma, a deadly form of skin cancer.

Here’s what the researchers discovered.

But first, what causes the hair to grey?

Over the years, our cells are constantly bombarded by both internal and external stressors, from UV radiation to oxidative stress, all of which can damage DNA.

At the centre of this process are melanocyte stem cells (McSCs), the tiny pigment-producing cells responsible for giving hair and skin their colour. These cells sit in a specialised area near the base of hair follicles, known as the “bulge-sub-bulge” region, and continuously regenerate to keep our hair coloured through repeated growth cycles.

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When these melanocytes begin to decline or lose function, hair gradually loses its pigment, leading to greying.

What intrigued scientists, though, was why some of these stem cells simply die off harmlessly, while others stick around long enough to potentially become dangerous.

To find out, Professor Emi Nishimura and Assistant Professor Yasuaki Mohri from the University of Tokyo studied how these cells respond to DNA damage and the chemical signals they receive from surrounding cells, collectively known as their “niche.”

What did the study do?

The researchers behind the latest study turned to mice to observe how melanocyte stem cells (McSCs) react to different kinds of DNA damage.

They discovered something fascinating: when these pigment-producing cells are stressed, they take one of two paths: either they mature and leave the system, which causes hair to turn grey, or they keep dividing, which can increase the risk of tumour growth.

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In simple terms, when your hair starts to lose its colour, it might actually be your body’s way of preventing melanoma, a serious form of skin cancer.

“It reframes hair greying and melanoma not as unrelated events, but as divergent outcomes of stem cell stress responses,” said co-author Nishimura in a statement.

Nishimura’s team described this process as a kind of biological trade-off between ageing and cancer.

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Does grey hair prevent cancer?

The researchers were clear: this doesn’t mean grey hair prevents cancer. Rather, the stress-induced process that leads to greying could act as a natural defence, helping eliminate harmful cells before they become dangerous.

Still, Nishimura and her team noted that more studies are needed to fully understand the connection between greying hair and melanoma.

Melanoma is one of the deadliest forms of skin cancer because it can spread rapidly to other parts of the body if not caught early. Unlike other skin cancers, melanoma cells can travel quickly through the bloodstream and lymphatic system to infect other organs and tissues.

The risk of developing melanoma increases with age, the average age of diagnosis in the US is 66. However, it’s also among the most common cancers in people under 30, especially young women.

Other risk factors include being male, having multiple moles, a family or personal history of melanoma, and experiencing severe sunburns during childhood. People who spend long hours outdoors are also more vulnerable due to higher sun exposure.

With input from agencies