Reversing Gray Hair: Inspiring the Development of New Therapies Through Research on Hair Pigmentation and Repigmentation Progress 1 in 3 people under 30 have premature greying , Most of them are B12 deficient , Your hair didnt age your mitochondria did., #B12Deficiency Grey hair isnt age, its a signal., Your cells are Human Hair Graying Revisited: Principles, Misconceptions, and Key Research Frontiers ScienceDirect Hair turns grey when the cells that give it colour, called pigment cells, slow down or stop making pigment. These pigment makers sit near the base of each hair follicle and supply