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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.
Other Resources :
The
More You Know About Vitamins
The
More You Know About Nutrition
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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