Vitamin B6 (Pyridoxine)

Vitamin B₆ is a water-soluble vitamin. Our bodies use three forms of vitamin B₆: pyridoxine (PN), pyridoxal (PL), and pyridoxamine (PM). Most of the time you will hear vitamin B₆ referred to as pyridoxine. Vitamin B₆ performs several functions in our body, including breaking down carbohydrates for energy production, and forming hemoglobin and other substances that our bodies need to perform properly.

Uses

The uses of vitamin B₆ include the following:

• To improve the symptoms of vitamin B₆ deficiency. These symptoms include inflammation (redness, swelling, pain) of the mouth, chapped lips, irritability, depression, and confusion.
• To treat anemia and nervous systems disorders caused by tuberculosis drugs
• To treat patients who have taken an overdose of the tuberculosis drug isoniazid
• To reduce the symptoms of premenstrual syndrome (PMS)
• To reduce nausea and vomiting during pregnancy
• To prevent heart disease. Recent studies have shown that vitamin B₆, vitamin B₁₂, and folate can lower blood levels of homocysteine, a substance that is an independent risk factor for heart disease.

Dietary Sources

Chicken, fish, kidney, liver, eggs, and pork are excellent sources of vitamin B₆. The following are also good sources of vitamin B₆: yeast, wheat germ, whole grain cereals, beans, potatoes, bananas, and oatmeal.Vitamin B₆ can be lost from food that's frozen or processed (example: luncheon meats).

Other Forms

Vitamin B₆ is available in the form of pyridoxine hydrochloride. It is available as tablets in multivitamin form (including children's chewable), B-complex form, or by itself in dosages ranging from 1 mg to 150 mg. Vitamin B₆ is also found in children's multivitamin liquid drops.

How to Take It

To avoid vitamin B₆ deficiency, men should get 2.0 mg and women 1.5 mg of vitamin B₆ daily. Pregnant women need 2.2 mg of vitamin B₆ daily, and women who are breast-feeding need 2.1 mg daily. People who eat a balanced diet containing the sources of vitamin B₆ listed above should be able to meet the daily requirement without taking a supplement. Consult your health care provider if you have questions about your daily requirement of vitamin B₆. When taking a vitamin supplement, always take it with water, preferably after a meal. As with all medications and supplements, check with a health care provider before giving vitamin B₆ supplements to a child.

Precautions

Vitamin B₆ can cause neurological disorders when taken in high doses (200 mg per day or greater) over a long period of time. Discontinuing high doses usually leads to a complete recovery.

Possible Interactions

Anti-tuberculosis medications such as isoniazid (INH) and cycloserine (used for resistant forms of tuberculosis) reduce the levels of vitamin B₆ in the blood. For this reason, it is recommended that you take vitamin B₆ if you are taking these medications and that your doctor closely monitor you for signs of vitamin B₆ deficiency.

Additionally, vitamin B₆ reduces the therapeutic effect of levodopa, a medication used to treat Parkinson's disease.

Penicillamine (used in the treatment of Wilson's disease and rheumatoid arthritis) decreases levels of vitamin B₆ and may render this vitamin ineffective.

Long-term use of birth control medications may decrease blood levels of vitamin B₆.

Vitamin B₆ diminishes the effectiveness of hydralazine, a medication used for the treatment of high blood pressure.

Monoamine oxidase inhibitors, medications such as phenelzine and tranylcypromine that are used to treat depression, may reduce blood levels of vitamin B₆.

Supporting Research

Berger AR, Schaumburg HH, Schroeder C, Apfel S, Reynolds R. Dose response, coasting and differential fiber vulnerability in human toxic neuropathy: a prospective study of pyridoxine neurotoxicity. Neurology. 1992;42:1367–1370.

Bhagavan HN, Brin M. Drug-vitamin B6 interaction. Curr Concepts in Nutr. 1983;12:1-12.

Brush MG, Bennett T, Hansen K. Pyridoxine in the treatment of premenstrual syndrome: a retrospective survey in 630 patients. Br J Clin Pract. 1998;42:448–452.

Cardona, PD. [Drug-food interactions]. Nutr Hosp. 1999;14(Suppl 2):129S-140S.

Diegoli MS, da Fonseca AM, Diegoli CA, Pinoltti JA. A double-blind trial of four medications to treat severe premenstrual syndrome. Int J Gynaecol Obstet. 1998;62:63–67.

Ebadi M, Gessert CF, Al Sayegh A. Drug-pyridoxal phosphate interactions. Q Rev Drug Metab Drug Interac. 1982;4(4):289-331.

Ekhard ZE, Filer LJ, eds. Present Knowledge in Nutrition. 7th ed. Washington, DC: ILSI Press; 1996:191–201.

Folsom AR, Nieto FJ, McGovern PG, et al. Prospective study of coronary heart disease incidence in relation to fasting total homocysteine, related genetic polymorphisms, and B vitamins: the atherosclerosis risk in communities. Circulation. 1998;98:204–210.

Hardman JG, Limbird LE, eds. Goodman and Gillman's Pharmacological Basis of Therapeutics. 9th ed. New York: McGraw-Hill; 1996:1326–1333.

Harrison, W, Stewart J, Lovelace R, Quitkin F. Case report of carpal tunnel syndrome associated with tranylcypromine. Am J Psychiatry. 1983;140(9):1229-1230.

Heller CA, Friedman PA. Pyridoxine deficiency and peripheral neuropathy associated with long-term phenelzine therapy. Am J Med. 1983;75(5):887-888.

Keniston RC, Nathan PA, Leklem JE, Lockwood RS. Vitamin B6, vitamin C, and carpal tunnel syndrome. A cross-sectional study of 441 adults. J Occup Environ Med. 1997;39:949–959.

Mahan LK, Arlin MT, eds. Krause's Food, Nutrition, and Diet Therapy. 8th ed. Philadelphia, Pa: WB Saunders Co; 1992:96– 97.

National Research Council: Recommended Dietary Allowances. 10th ed. Washington, DC: National Academy Press; 1989: 158–165.

Ballal RS, Jacobsen DW, Robinson K. Homocysteine: update on a new risk factor. Cleve Clin J Med. 1997;64:543–549.

Gospe SM. Current perspectives on pyridoxine-dependent siezures. J Pediatr. 1998;132:919-923.

Murphy PA. Alternative therapies for nausea and vomiting of pregnancy. Obstet Gynecol. 1998; 91:149-155.

O'Connell BJ. The pediatrician and the sexually active adolescent: treatment of common menstrual disorders. Pediatr Clin North Am. 1997;44:1391–1404.

Otomo S, Sasajima M, Ohzeki M, Tanaka I. Effects of D-penicillamine on vitamin B6 and metal ions in rats [in Japanese]. Nippon Yakurigaku Zasshi. 1980;76(1):1-13.

Recommended Dietary Allowance. American Academy of Sciences. Accessed at www.nal.usda.gov/fnic/Dietary/rda.html on January 8, 1999.

Seelig MS. Auto-immune complications of D-penicillamine – a possible result of zinc and magnesium depletion and of pyridoxine inactivation. J Am Coll Nutr. 1982;1(2):207-214.

Shumann K. Interactions between drugs and vitamins in advanced age. Int J Vitam and Nutr Res. 1999;69(3):173-178.

Vidrio H. Interaction with pyridoxal as a possible mechanism of hydralazine hypotension. J Cardiovasc Pharmacol. 1990;15(1):150-156.

Wada M. The adverse reactions of anti-tuberculosis drugs and its management [in Japanese]. Nippon Rinsho. 1998;56(12):3091-3095.

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