Why Does Hair Turn Grey?

Hair colour comes from a pigment called melanin, produced by specialised cells called melanocytes located in each hair follicle. There are two types: eumelanin (brown and black tones) and pheomelanin (red and yellow tones), and their ratio determines natural hair colour. As we age, the melanocyte stem cells that replenish these pigment cells gradually become depleted or dysfunctional, so less melanin is produced. Hair with reduced melanin appears grey, and hair with no melanin appears white (grey hair is actually a mix of pigmented and white strands). The timing is largely genetic — if your parents greyed early, you likely will too. On average, Caucasians begin greying in their mid-30s, Asians in their late 30s, and Africans in their mid-40s. Oxidative stress also plays a role: hair follicles produce small amounts of hydrogen peroxide, which can build up and bleach hair from within as the enzymes that normally break it down decline with age. Stress, smoking, and certain vitamin deficiencies can accelerate greying.