Why hair turns gray, and what you can do about it

By Kathleen Felton

For The Washington Post

Whether you’re embracing new silver growths or attacking them strand by strand with tweezers, gray hair is an inevitable part of getting older.

“Just as the skin ages and the rest of the organs in your body age, the hair ages, too,” said Helen He, an assistant professor in the Kimberly and Eric J. Waldman Department of Dermatology at the Icahn School of Medicine at Mount Sinai.

The going-gray process happens at different speeds for different people, she said, but most of us start to notice increasing gray hair sometime in our 30s or 40s, according to the American Academy of Dermatology. Around this time, melanocyte stem cells, which are hair follicle cells responsible for depositing pigment into the hair shaft, can start to become depleted or dysfunctional.

“There’s not really a whole lot known about why the melanocyte stem cells die off,” said George Cotsarelis, chair of the dermatology department at the Perelman School of Medicine at the University of Pennsylvania and a hair-follicle stem-cell researcher. But there are a number of reasons, including stress or DNA damage, “that are thought to maybe prevent these stem cells from surviving,” he said.

The process, called cellular senescence, causes hair to “gradually lose its pigment over time,” He said. Strands that previously were black, brown, red...