Can 16 year old gray hair become black, related to the cause of becoming gray hair, if it is caused by acquired factors and the appearance of white hair, usually can become black. I. Congenital factors: (1) If 16-year-old long white hair is related to heredity, due to genetic mutation caused by the formation of true melanin and brown melanin, tyrosine metabolism pathway is blocked, resulting in hair color abnormality, this situation generally can not be turned into black hair. II. Acquired factors: (1) Lack of nutrition: Hair is an appendage of the skin, and at the same time, it needs sufficient nutrition. If the organism lacks protein, vegetable oil, vitamins and other nutrients for a long time, it will also lead to the situation that the hair becomes white. And this situation can be adjusted to improve the diet structure, avoid picky eating, partiality, usually balanced diet. (2) too much mental stress: if at the age of 16 to age study pressure is too much, resulting in mental state has been in tension, will cause hair white. This situation requires appropriate regulation of pressure, work and rest, appropriate rest, some patients will be in the spirit of relaxation, gray hair will gradually improve. During this period, you should combine work and rest, do not stay up late, and keep a relaxed mood, in order to be more conducive to the recovery of the symptoms.