Tsuara - About.com User
Vitamin B6 is needed for many functions in the body, including the protein metabolism, healthy red blood cells and immune system function. It is also needed for normal nerve function and production of brain chemicals called neurotransmitters. This has lead some people to believe that using large doses of vitamin B6 may be helpful for disorders, such as depression, carpal tunnel syndrome and premenstrual syndrome. Unfortunately, research has not shown vitamin B6 to actually be beneficial for any of these disorders. Vitamin B6 will reduce homocysteine, which is a risk factor for cardiovascular disease.
Most multivitamins have only a small amount of vitamin B6, but be careful with dietary supplements that contain large amounts of vitamin B6. The Food and Nutrition Board of the Institute of Medicine has established an upper tolerance of only 100 mg of vitamin B6 per day. Very large amounts, over 500 mg per day, may cause nerve damage.
Sources:
Food and Nutrition Board, Institute of Medicine, National Academies. "Dietary Reference Intakes (DRIs): Recommended Intakes for Individuals, Vitamins." Published 2004.
National Institutes of Health Office of Dietary Supplements. "Dietary Supplement Fact Sheet: Vitamin B6."
