VITAMIN B6 (Pyridoxine)
Vitamin B6 is an essential water-soluble nutrient and a member of the B COMPLEX. The term “vitamin B6” pertains to two forms, pyridoxine and pyridoxamine, which can be converted back and forth. Vitamin B6 is required by the body to produce non-essential AMINO ACIDS, to break down most amino acids, and to support healthy immune systems, normal immunity and nerve function. However, before it can help enzymes, vitamin B6 like other B complex vitamins must be activated. The enzyme helper (COENZYME) in this case is pyridoxal phosphate, employed by a family of enzymes called transaminases required in the first stage of amino acid utilization by the body.
Chemicals known as hydrazides and hydrazines interfere with the functions of vitamin B6. These chemicals are widely used in industry and contaminate the food supply. Derivatives of hydrazines appear in cigarette smoke and food additives; thus the environmental burden could deplete this nutrient.
Possible Roles in Maintaining Health
Red blood cells Vitamin B6 is essential for the production of RED BLOOD CELLS. Vitamin B6 plays a role in protein synthesis as well as in the synthesis of DNA and RNA, and it is required to make HEME, the red pigment of the oxygen transport protein of blood (HEMOGLOBIN). A deficiency can cause anemia.
Nervous system The formation of certain brain chemicals (NEUROTRANSMITTERS) from amino acids requires this vitamin; hence it affects the NERVOUS SYSTEM. Certain inherited metabolic disorders lead to convulsions in infants, and B6 supplementation usually abolishes their seizures.
Immune system Vitamin B6 is one of the most important B vitamins in maintaining a robust IMMUNE SYSTEM. Vitamin B6 supplements can boost immunity in older people who may not consume enough of this important vitamin. Vitamin B6 deficiency decreases immune function in humans and lab animals, and low vitamin B6 levels are common in people with weakened immunity, including people with CANCER and AIDS. Vitamin B6 also protects against certain types of cancer in lab animals.
Premenstrual syndrome (PMS) Vitamin B6 has long been claimed to relieve an array of symptoms occurring in the week to 10 days prior to menstruation. PMS affects the synthesis of several hormones believed to be involved in the cycle. Vitamin B6 has been used to correct for some of the imbalances caused by estrogen-type birth control pills.
Carpal tunnel syndrome Vitamin B6 supplementation is often an effective treatment of carpal tunnel syndrome, in which there is compression of a nerve in the wrist. Large doses are used for several months.
High blood sugar Vitamin B6 has been used to help treat diabetic patients whose condition can be attributed in part to a deficiency of this vitamin. B6 supplementation has increased GLUCOSE TOLERANCE, the body’s ability to remove glucose from the blood, and decreased insulin requirements in certain patients with gestational diabetes. INSULIN is the pancreatic hormone that stimulates tissue uptake of glucose.
Cardiovascular disease Vitamin B6 may decrease the stickiness of platelets, cell fragments in the blood needed for clot formation, and thus the tendency to form blood clots. A deficiency of this vitamin has been linked to ATHEROSCLEROSIS in some instances, due to an accumulation of excessive amounts of an amino acid, Homocysteine and its breakdown products.
Senility Vitamin B6 deficiency is linked to long-term memory loss in some elderly patients.
Other Conditions Some forms of arthritis and joint pain respond to extra vitamin B6. In combination with magnesium this vitamin can lower the risk of calcium oxalate kidney stones, the most common kind. Vitamin B6 deficiency is common among patients with asthma.
Sources
Vitamin B6 occurs in FISH; MEAT, including liver and kidneys; BLACKSTRAP MOLASSES; NUTS and whole GRAINS; BREWER’S YEAST; and many VEGETABLES.
Requirements
The Recommended Dietary Allowances (RDA) for adults (25 to 50 years) is 2.0 mg for men and 1.6 mg for women. Many people do not obtain adequate amounts of this vitamin and it is one of the most common deficiencies. Those most at risk are older persons; it has been found that 61- to 71-year-olds need more vitamin B6 than the RDA. Others who may not consume enough vitamin B6 include adolescent women and pregnant and lactating women, alcoholics, and those with other chemical dependencies.
Factors that may increase the need for vitamin B6 include alcohol, several medications (L-dopa, penicillamine, hydralazine, and isoniazid), smoking, a high protein diet, and deficiencies of magnesium, ZINC and RIBOFLAVIN. A mild deficiency is sometimes associated with lowered immunity and nervous disorders. Severe deficiency causes depression, confusion, convulsions, inflamed mouth, and tongue, and skin disorders. The optimal amount for maximal health and longevity is not known.
Safety
There is general agreement that amounts up to 50 mg per day are relatively safe. Higher levels should be taken only with professional advice. Excessive consumption of vitamin B6 can damage the nervous system and lead to numbness of hands and feet (peripheral neuropathy). Insomnia and anxiety are possible symptoms of excessive intake. Vitamin B6 reduces the effectiveness of levodopa, a drug used to treat PARKINSON’S DISEASE.
Dakshinamurti, Krishnamurti, ed., “Vitamin B6,” Annals of the New York Academy of Sciences, 585 (1990).