Jeff Angileri
Mar 25, 2009, 9:32 PM

It's commonly called a sign of wisdom many of us would rather do without, but grey hair is a fact of life for lots of people. Now, a group of European researchers say they've figured out why human hair turns grey.

According to a recent study from the Federation of the American Societies for Experimental Biology, hair color is altered by a chemical called hydrogen peroxide. Researchers say all hair cells make a tiny amount of hydrogen peroxide. But as we get older, a little becomes a lot. That's because hair follicles suffer wear and tear as we age and the enzymes that repair the damage decrease over time. Researchers say the peroxide ends up blocking the production of melanin, which gives our hair and skin its natural color.

There are color cells in the base of the hair follicle. They just gradually over time stop making pigmentation at the same rate, and eventually stop making pigmentation all the way, said Dr. Bob McDonald, Dean Health Dermatologist.

And, doctors say, genetics also plays a role.

The rule of thumb is 50 percent of people are 50 percent grey at age 50, Dr. McDonald said.

But on a positive note, there's no link between grey hair and overall health.

Developing grey hair is a normal tendency, said Dr. McDonald. It's probably set from the time you're born. And there's really nothing you can do to change that. It's not really related to tight caps or stress or anything else.

When it comes to coloring hair, Dr. McDonald says coloring is actually safe as long as you're not allergic to the dye. Getting a perm, however, is damaging, and not recommended.

Doctors say grey hair can happen at any age. Premature greying can happen to people as young as 25.