hi..Thanks for the query. Hair goes gray when color-producing cells stop producing pigment.Naturally occurring hydrogen peroxide can also build up in the hair, bleaching the color.Going gray, by itself, does not mean you have a medical problem, except in rare cases.Scientists don’t know exactly why some people go gray early, but genes play a large role.There are several proposed causations about the same: 1) stress has been shown to cause gray hair 2) vitamin B-12 deficiency 3) pituitary or thyroid gland can cause premature graying that’s reversible if the problem is corrected. 4)Vitiligo is an autoimmune disease caused by destruction of the pigment producing melanocytes that give hair and skin its pigment. This leads to depigmented areas on the skin as well as prematurely gray hair. Please try to rule out the above first. Start taking supplements for the nutritional deficiencies.it is necessary to include a diet that is rich in Vitamin B, iron and iodine. Hope this helps..Take care1