Vitamins, Minerals and Dietary Supplements
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;38:485-91.
- Gaby AR. Literature review & commentary. Townsend
Letter for Doctors June 1990;338-39.
- Vitamin B6 in the treatment of the premenstrual syndrome.
Review. Br J Obstet Gynaecol 1991;98(3):329-330.
