Expert Nutrition

Vitamin B6
(Pyridoxine, Pyridoxal and Pyridoxamine)

Vitamin B6 is one of the essential, water soluble, B-complex vitamins. It plays an important role in the release of energy from carbohydrates and fats, is required for proper nerve function and in the making of red blood cells. Vitamin B6 also assists in the metabolism of protein and in the conversion of tryptophan (an amino acid found in dietary protein sources) into niacin, another B-complex vitamin.

Vitamin B6 comes in three forms; pyridoxine, pyridoxal and pyridoxamine. Pyridoxine is predominately found in plant foods, whereas the other two forms pyridoxal and pyridoxamine generally exist in animal foods. Major food sources of vitamin B6 include meat, fish, poultry, grains and cereals, green leafy vegetables, potatoes and soy beans.

A deficiency of vitamin B6 on its own is rare, it is most commonly seen with deficiencies of other nutrients including protein and other vitamins, however can also result as a side effect to some prescriptions medications. The symptoms of vitamin B6 deficiency are not specific, but generally include weakness, sleeplessness, peripheral neuropathy, dermatitis, anaemia and impaired immunity. More than 80% of vitamin B6 deficiency cases are due to alcoholism, which can impair vitamin B6 absorption. As discussed in other chapters of this website, alcoholism can often be the underlying cause of a number of B vitamin deficiencies.

It is interesting to note that pregnant women are often seen to have a reduction of vitamin B6 plasma levels, but it is unclear if this is due to a deficiency or if it is a normal physiological change of pregnancy.

Unlike other water soluble vitamins, B6 is stored in muscle tissue and can accumulate to toxic levels. It is suggested to avoid doses in excess of 200mg (check your supplements) which can lead to sensory impairment and interfere with some medications. Please refer to the chapter on Nutritional Supplements for more advice on toxicity.

Additional Possible Benefits of Vitamin B61

  • May protect against heart disease

Recommended Dietary Intake for Vitamin B6

A recent re-evaluation of dietary requirements for all vitamins and minerals was published by the National Health and Medical Research Council. The dietary recommendations for vitamin B6 from this publication are summarised below.

Please refer to the following definitions when interpreting these recommendations:

RDI-Recommended Daily Intake
The average daily intake level that is sufficient to meet the nutritional requirements of nearly all (97-98%) health individuals in a particular life stage and gender group.

AI-Adequate Intake (used when an RDI cannot be determined)
The average daily nutrient intake level based on observed or experimentally-determined approximations or estimates of nutrient intake by a group (or groups) of apparently healthy people that are assumed to be adequate.

UL-Upper Limit of Intake
The highest average daily nutrient intake level likely to pose no adverse health effects to almost all individuals in the general population. As intake increases above the UL, the potential risk of adverse effects increases.

RECOMMENDATIONS BY LIFE STAGE AND GENDER - Vitamin B6

Infants AI UL

All
0-6 months0.1 mg/day *
7-12 months 0.3 mg/day *

Children and AdolescentsRDIUL

All
1-3 years 0.5 mg/day 5 mg/day
4-8 years 0.6 mg/day 20 mg/day

Boys
9-13 years 1.0 mg/day 30 mg/day
14-18 years 1.3 mg/day 40 mg/day

Girls
9-13 years 1.0 mg/day 30 mg/day
14-18 years 1.2 mg/day 40 mg/day

AdultsRDI UL

Men
19-30 years 1.3 mg/day 50 mg/day
31-50 years 1.3 mg/day 50 mg/day
51-70 years 1.7 mg/day 50 mg/day
>70 years 1.7 mg/day 50 mg/day

Women
19-30 years 1.3 mg/day 50 mg/day
31-50 years 1.3 mg/day 50 mg/day
51-70 years 1.5 mg/day 50 mg/day
>70 years 1.5 mg/day 50 mg/day

Pregnancy
14-18 years 1.9 mg/day 40 mg/day
19-30 years 1.9 mg/day 50 mg/day
31-50 years 1.9 mg/day 50 mg/day

Lactation
14-18 years 2.0 mg/day 40 mg/day
19-30 years 2.0 mg/day 50 mg/day
31-50 years 2.0 mg/day 50 mg/day

* Not possible to establish, source of intake should be breast milk, formula or food only.

Source: National Health and Medical Research Council. Nutrient Reference Values for Australia and New Zealand. Department of Health and Ageing, Canberra 2006, copyright Commonwealth of Australia reproduced by permission.

Vitamin B6 back to Vitamins


References:
1. The Merck Manual of Medical Information 2nd Ed. Beers, M.H., Fletcher, A. J., Jones T. J., Porter, R., Berkwits, M., et al., editors. Pocket Books Reference; 2003
2. Wahlqvist, M.L., et al. Australia and New Zealand: Food and Nutrition. 2nd Ed. Allen and Unwin, Sydney; 2002, pp 253-256.
3. Stanton R. Foods that harm, foods that heal: An A-Z guide to safe and healthy eating. Readers Digest; 2006, pp 378-382.
4. Mann, J., Truswell, S. Essentials of Human Nutrition. Oxford Medical Publications, New York. 2000
5. National Health and Medical Research Council. Nutrient Reference Values for Australia and New Zealand. Department of Health and Ageing; 2006 pp 85-90, copyright Commonwealth of Australia reproduced by permission.


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