4 Fascinating Things Every Woman Should Know About Gray Hair

Certain vitamin deficiencies are linked to premature graying, and B12 deficiency has the strongest evidence behind it, says Ngo. "B12 is involved in hair recycling and growth," Ngo explains, so when you're not getting enough of it, it can affect the color of your strands. One study published in The International Journal of Trichology found that levels of B12 were significantly lower in people with premature graying than in those whose hair hadn't started to go gray yet. Ngo says that there's also some research linking a lack of vitamin D to premature graying, but that more studies need to be done to confirm it.