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Despite the general consensus, white hair isn't always related to age. Premature graying can occur in teenagers and young adults. Primarily, hair is white. A pigment in the cells called melanocyte gives hair color. The more melanocyte there is, the darker the hair color will be. This is what creates blond or brunette hair. In old age, the body produces less melanocyte, producing gray hair. However, there are many reasons for gray hair in young adults.

Genetics

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The director of the Center for Dermatology, Cosmetic, and Laser Surgery in Mount Kisco, N.Y., reports premature graying is predetermined by genetics. If your parents had premature graying, you will most probably also have premature graying. A person's genes determine when the production of melanin in the body stops. When melanin decreases, the color pigments in the hair also decrease, causing gray hair.

Vitamin Deficiency

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Malnutrition and vitamin deficiency, mainly B-12, also contribute to premature graying. B-12 is necessary for hair color. Sometimes the lack of B-12 is a symptom of a concealed disease, usually pernicious anemia. In pernicious anemia, the body becomes unable to absorb B-12, hence turning the hair gray. The lack of vitamins E, C, A, B-6, niacin and biotin are linked to gray hair. Your diet should be rich in protein, milk, egg yolks, whole grain cereals and vegetables.

Smoking

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A 1996 study published in the "British Medical Journal" proposes a direct link between smoking and premature graying. Although it isn't medically proven, a survey conducted by Dr. J. G. Mosley shows smokers gray much quicker than nonsmokers.

Thyroid Stimulating Hormone

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When the thyroid gland isn't able to produce enough thyroid hormone, a condition called hypothyroidism occurs. According to the University of Michigan Health System, premature graying is a side effect of hypothyroidism. Other symptoms include dry skin, brittle nails, fatigue and constipation. It can be diagnosed by a thyroid ultrasound or a thyroid scan.Thyroid hormone is available in some health stores, but you should talk to a doctor before taking medicinal supplements.

Treatment

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If your hair is graying prematurely, consult your doctor on the conditions that can cause this. Otherwise, try some home remedies. Try massaging Indian gooseberry, almond oil and a few drops of lemon juice into your scalp on a nightly basis. The intake of curry leaves, butter from cow's milk and vitamins may help counteract premature graying.