Scientists narrow in on the cause of hair greying

What's the news: Scientists now know what causes gray hair, at least in mice.

Why should we believe it: This news is based on a study published two weeks ago in Nature. The study was performed by scientists at New York University Grossman School of Medicine.

The scientists discovered something unexpected: Cells that produce hair pigment move around the hair follicle and switch between stem-cell and fully developed states.

But with time, these cells stop making the switch effectively. They get stuck in the stem-cell state, and cannot transition back into fully grown, pigment-producing cells. This is a revelation in contrast to previous theories, which thought that grey hair is the result of a lack of stem cells.

Scientists might be able to figure out the proteins that signal to stem cells it's time to transition to a mature state. This could prevent and even reverse grey hair, not only in mice, but also in humans – who share the same kinds of cells with mice.

So what specifically can you do now: This study only offers an explanation, and not a treatment — and in mice to boot. If you want to prevent, or possibly reverse grey hair, for now you are left with the usual suspects: fixing nutritional deficiencies, managing or avoiding extreme stress, or applying hair dye.