Here’s the science. Hair gets its color from melanocytes, pigment-producing cells that live near the base of each hair. As you age, your melanocytes begin to produce less melanin, fail to produce melanin altogether or simply die off, resulting in those new gray locks. Meanwhile, hydrogen peroxide (a powerful bleaching agent) is always being produced naturally in the hair follicle, but is broken down by enzymes. As you age, those enzymes dwindle, letting the hydrogen peroxide bleach hair from the inside out. But there’s big news: Researchers in Germany have just discovered a topical treatment that can stop the bleaching reaction, bringing your color back from the brink.