Going grey could be your body's way of fighting off cancer, scientists say. Growing grey hair has never been more positive, as a new study from the University of Tokyo in Japan found that those salt and pepper locks may signal your body is destroying damaged cells before they turn cancerous.
Grey hair might be more than just a sign of getting older, it could be your body's way of stopping cancer in its tracks, according to new research from the University of Tokyo. Scientists found that when certain pigment-producing stem cells in mice suffered DNA damage, some of them self-destructed instead of turning cancerous, leading to white fur.
The groundbreaking result suggests that going grey happens when the body's natural cancer-fighting system, known as the p53-p21 pathway, kicks in to destroy potentially dangerous cells. If this protective signal is weak, the risk of cancer goes up.
The study, published in Nature Cell Biology, further suggests that white hair could actually be a warning sign that your body is fighting off cancer at the cellular level. The researchers wanted to know, "Why do some stem cells die or disappear when their DNA is damaged, while others survive and transform into cancer cells?"
To find out, they looked at the cells that make hair colour, melanocyte stem cells (McSC), and exposed mice to strong sunlight and chemicals. Some of these cells realised they were damaged and killed themselves off, which made the mice's fur turn white.
Other cells kept growing even though they were damaged, which could lead to cancer. The researchers subsequently found that there's a special signal in the body that can inform these cells to self-destruct and cause grey hair.
If this signal doesn't work properly, the risk of cancer goes up. The scientists said: "Hair turning white may not simply be an aging phenomenon but a biological defence response that blocks the path to cancer by eliminating damaged cells."
Published in Nature Cell Biology, the study from Professor Emi Nishimura and Assistant Professor Yasuaki Mohri found that when these cells face certain types of DNA breaks, they go through a process called "senescence-coupled differentiation (seno-differentiation)".
Professor Nishimura said: "These findings reveal that the same stem cell population can follow antagonistic fates, exhaustion or expansion, depending on the type of stress and microenvironmental signals.
"It reframes hair greying and melanoma not as unrelated events, but as divergent outcomes of stem cell stress responses."
Nevertheless, the researchers also noted that getting grey hair does not stop you from getting cancer. Instead, it shows that when hair turns grey, it's because the body is getting rid of damaged cells as a way to protect itself.
However, if this safety system fails and the damaged cells stick around, there's a bigger risk of skin cancer. As a result, the research helps explain how getting older and getting cancer are connected, and why it's actually good for the body to clear out suspicious cells.