Vitamin B6 is required for amino acid and red blood cell metabolism. It is also needed to make serotonin, dopamine and melatonin, so it is an essential element in the regulation of mental processes, and possibly, mood.
Since Vitamin B6 is involved in protein metabolism and cell growth, it's important to the immune system. It helps maintain health of the lymphoid organs that make white blood cells. Vitamin B6 has been known to lower homocysteine levels. Homocysteine has been linked to osteoarthritis, heart disease, stroke and Alzheimer's disease.
An upper tolerance limit of 100 mg per day has been established. Because of side effects, it is recommended that people typically take no more than the RDI.
2 mg
As with other B vitamins, deficiency is rare. Deficiency causes impaired immunity, skin lesions, and mental confusion.
Excessive supplementation (200 mg or more) can cause numbness in hands and feet and difficulty walking
Vitamin B6 increases the bioavailability of magnesium so the two are often taken together. Vitamin B6 with folate is better than folate alone in decreasing homocysteine levels.
Vitamin B-6 is found in beans, nuts, legumes, eggs, meats, fish, whole grains, and fortified breads and cereals
Vitamin B6 has widely been used to treat carpal tunnel syndrome and PMS, but it hasn't been shown to be effective for either condition. Alcoholics should take Vitamin B6 supplements.
Asthma drugs, oral contraceptives, certain antibiotics and corticosteroids decrease body stores of vitamin B6. Patients undergoing chemotherapy with certain drugs may benefit from Vitamin B6 supplementation to help treat side effects as well as prevent deficiency.
Ames BN
DNA damage from micronutrient deficiencies is likely to be a major cause of cancer.
Mutat Res. 2001 Apr 18;475(1-2):7-20. Review.
This is fascinating. A deficiency of any of the micronutrients: folic acid, Vitamin B12, Vitamin B6, niacin, Vitamin C, Vitamin E, iron, or zinc, mimics radiation in damaging DNA by causing single- and double-strand breaks, oxidative lesions, or both. This helps explain why people who eat the fewest fruits and vegetables have double the cancer risk.