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Vitamins, Minerals and Dietary Supplements

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Vitamin B6 (Pyridoxine)

What is vitamin B6?

Also known as pyridoxine, vitamin B6 is a water-soluble vitamin absorbed by the intestines and carried throughout the body in the bloodstream. Since it is not stored in body fat, after the body uses what it needs, any excess vitamin B6 is excreted in urine or sweat.

Why do we need it?

Vitamin B6 is considered the "master vitamin" in the processing of amino acids. It helps build up and break down amino acids and is needed to make serotonin, melatonin and dopamine. It also aids in the production of red and white blood cells, converts a substance called tryptothan to niacin, and plays a role in the metabolism of proteins and fats. Large doses of B6 may reduce the symptoms of premenstrual syndrome, carpal tunnel syndrome and depression.

How much vitamin B6 should I take?

According to the National Academy of Sciences, the recommended daily allowance (RDA) for pyridoxine is as follows:

  • Adult men: 2 milligrams/day
  • Adult women: 1.6 milligrams/day
  • Children aged 7-10: 1.4 milligrams/day
  • Infants: 0.6 milligrams/day
  • Pregnant/lactating women: 2.2 milligrams/day

What are some good sources of vitamin B6?

The best sources of pyridoxine include meats, oily fish (especially tuna), poultry, legumes and leafy green vegetables. Other good sources include potatoes (with skins), avocados, watermelon, bananas, carrots, brewer's yeast and fortified cereals.

What can happen if I don't get enough vitamin B6?

Vitamin B6 deficiency is rare. However, alcohol and tobacco have been shown to impair the absorption of B6, as have a number of drugs, including ethionamide, hyrdalazine and penicillamine.

B6 deficiency can cause skin problems and nervous system disorders, including impaired memory and concentration. A lack of B6 has also been associated with increased levels of the chemical homocysteine, which in turn has been associated with heart disease, birth defects, Alzheimer's disease and possibly dementia. Increasing one's intake of fruits and vegetables may reduce homocysteine levels.

What can happen if I take too much?

Taking very high doses (>2,000 mg per day) of pyridoxine for months or years can cause numbness in the feet and hands, which may be permanent in some cases. Supplementation should be stopped immediately if any of these symptoms begin to develop. Pyridoxine also reduces the effects of L-dopa, a drug used to treat Parkinson's disease.

References

  • B vitamins may cut heart disease risk. Harvard Health News April 1998.
  • Vitamins and minerals A to Z glossary. Available from Intelihealth (www.intelihealth.com).
  • Getting enough folate and B6. Health News March 10, 1998.
  • Franzblau A, Rock CL, Werner RA, et al. The relationship of vitamin B6 status to median nerve function and carpal tunnel syndrome among active industrial workers. J Occup Environ Med 1996;38:48591.
  • Gaby AR. Literature review & commentary. Townsend Letter for Doctors June 1990;33839.
  • Vitamin B6 in the treatment of the premenstrual syndrome. Review. Br J Obstet Gynaecol 1991;98(3):329-330.

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