There is no proof of any product, medicine, supplement, herb or diet that can reverse gray hair. Thyroid disorders, vitamin B12 deficiency, anemia, vitiligo, menopause and smoking are causes of grey hair that are not necessarily related to aging and can be remedied to prevent grey hair.
A doctor can determine if thyroid conditions are the cause of premature grey hair, and treatment of thyroid disease can halt the occurrence of greys. Diets low in vitamin B12 as well as stomach and small-intestine-related surgery can cause deficiency anemia, which is linked to grey hair. One can also remedy premature grey hair by determining if tapeworms or an autoimmune issue is the cause of discolored hair. There is no cure for vitiligo, and early menopause can be leveled by medical treatment to prevent premature grey hair. Finally, quitting smoking on can prevent a premature grey hair color.