First, it is true that graying hair is due to an aging of sorts—but of your melanocytes in your hair bulb. These are the same cells that produce pigment in your skin, says Melissa Piliang, M.D., a dermatologist at the Cleveland Clinic.
“They gradually stop producing melanin pigment. The result is initially hair graying and then whitening over time," she says. This process does not affect the keratinocytes, which are responsible for producing the hair fiber, so there should not be any changes to your hair structure. However, you may also notice a change in the texture of your hair, like it becoming more coarse or wiry.
Not everyone goes gray at the same time, which can be frustratingly obvious if you’re sporting silver in your 30s while your old high school buddy still has glossy, dark hair.
"Up to 90 percent of the variation in hair graying can be explained by genetic factors, but we still have limited knowledge about the actual genes responsible," says Steve Daveluy, M.D., assistant professor and program director of Wayne State Dermatology.
That’s one reason why your ethnicity matters for your going-gray potential: "The average age that hair starts going gray is the mid 30s for Caucasians, late 30ss for Asians and mid 40s for Afro-Caribbeans," he says.
There are some general benchmarks for graying, though.
"About 50 percent of people are 50 percent gray by age 50," says Dr. Piliang.
But if you’re graying well before that time frame, does that mean your body is aging way too fast? Might other aspects of your health be in danger?
That’s a common question, and it’s one that researchers have sought to answer. And there is some evidence that early graying can hint at some health issues, particularly to your heart.
For instance, a study presented at the 69th Annual Conference of the Cardiological Society of India found that men under 40 with premature graying were more than five times as likely as their gray-free counterparts to have coronary artery disease, a narrowing of the arteries that can lead to heart attack. Back in 2012, researchers from the U.K. theorized that the aging of the melanocytes that causes graying could be due to oxidative stress, a biological process that could damage healthy cells and tissue. So the same process going on in your hair cells might be going on elsewhere in your body, too.
But don’t freak out just yet. The evidence in favor of premature graying hurting your heart still isn’t very strong, says Dr. Daveluy.
That doesn’t mean you shouldn’t play the preventive game if silver strands keep popping up, though.
"If you do have significant graying before the age of 35, it would be a good idea to make sure you talk to your doctor about optimizing other risk factors for heart disease, like diet, exercise, weight, high blood pressure, high cholesterol," says Dr. Daveluy.
That means it can’t hurt to be extra vigilant about your heart health if you’re going gray. But a few strands of gray hair likely don’t mean as much danger to you heart as known heart-unhealthy habits, like gaining too much weight, smoking, eating junk, or skipping the gym. While you can’t control when you’ll go gray, you are in charge of those other factors—so make them your main focus when thinking about your heart.