Download Vitamin B-6

Vitamin B-6 (Pyridoxine)
General Description
Vitamin B-6 is a water-soluble vitamin in the B-complex vitamin group.
The B vitamins are used by the body as coenzymes, which make
biochemical reactions possible. B-6 consists of three substances,
pyridoxine, pyridoxal phosphate, and pyridoxamine. All three forms can
be utilized by the human body, but only pyridoxine is officially
designated as B-6. Pyridoxine deficiency can result in skin and nervous
system disorders, dizziness, convulsions, kidney stones, and anemia.
Food sources
Vitamin B-6 is found in foods such as meats and organ meats, poultry,
whole-grain cereals and bread, avocadoes, spinach, green beans,
sunflower seeds, and bananas.
Health applications
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Homocysteine
Tardive dyskinesia
Asthma
Celiac disease
Kidney stones
Autism
Premenstrual syndrome
Functions and uses
Vitamin B-6 enables many enzymatic reactions in the body. The brain
and central nervous system require B-6 as a catalyst for the formation of
their chemical transmitters. B-6 is needed for the conversion of
carbohydrates into energy, and of tryptophane into nicotinic acid
(vitamin B-3). It also plays a role in the formation of red blood cells and
the metabolism of amino acids.
Homocysteine
Many of the health benefits provided by pyridoxine relate to its role in
controlling plasma homocysteine levels. High blood homocysteine levels
may contribute to thrombosis,1 atherosclerosis,1,2,3 coronary artery
disease,3,4 and cardiovascular disease.5 Studies indicate that
pyridoxine can reduce plasma homocysteine levels and that this action
is enhanced by the inclusion of folic acid.3
Tardive dyskinesia
There is conflicting evidence regarding the efficacy of pyridoxine in
treating tardive dyskinesia. Early studies were not encouraging,
however there is case study evidence which suggests that pyridoxine
may reduce the frequency and intensity of the involuntary movements
associated with the disorder.6,7
Asthma
In one case study, 76 children with severe bronchial asthma were
treated daily with 200 mg of pyridoxine, while their dosage of
bronchodilators and cortisone was reduced. The study indicates that
each showed improvement in their symptoms from this 5 month
treatment.8 However, other studies indicate that pyridoxine does not
improve the symptoms of severe asthma and that such treatment is
unjustified.9
Kidney Stones
Studies suggest that large treatments of pyridoxine may decrease
oxalate production, and that this may help prevent calcium oxalate
kidney stone formation.10,11 However, more long-term studies are
needed to further elucidate its effectiveness as a viable and consistent
treatment for those at risk of kidney stones.
Autism
Linus Pauling's orthomolecular hypothesis states that some forms of
disease and mental illness are related to biochemical errors in the body.
There is evidence that vitamin therapy can counteract some of these
errors. For example, studies demonstrate that pyridoxine and
magnesium supplementation may improve many symptoms of
autism.13-17 Researchers cite clinical as well as empirical evidence in
support of this therapy, but additional long-term studies are needed
before definitive conclusions can be drawn.12
Premenstrual syndrome
There is conflicting evidence as to the efficacy of pyridoxine in the
treatment of depression related to premenstrual syndrome. 18 Some
trials demonstrate that pyridoxine can improve PMS-induced
depression,19 however there are no significant conclusions on the
subject. Long term intake of B-6 at high doses can be toxic. Therefore,
regarding pyridoxine and PMS-induced depression, it is generally
recommended that a normal dietary intake of pyridoxine may provide
the most benefits with the least risk.
Dosage and Toxicity
If taken in large doses, B-6 can cause varied neurological symptoms
such as numbness in the hands and feet, and a general loss in sensory
perception. It is generally considered nontoxic when taken in doses up
to 100 mg daily. Because B-6 is needed to process protein, an
increased dietary intake of protein necessitates increased consumption
of B-6. The RDI recommendation is 2 mg of vitamin B-6 for every 100
grams of dietary protein.