COT statement on vitamin B6 (pyridoxine) toxicity (June 1997)

The COT was asked to advise on the safety of Vitamin B6, following concerns expressed about the potential toxicity of high dose dietary supplements.

Conclusions

There is no doubt that consumption of vitamin B6 by humans in excess of the amount required to maintain bodily function can result in symptoms which are consistent with sensory peripheral neuropathy. Furthermore, the animal toxicity data are consistent with the study of Dalton and Dalton (1987) which reported adverse effects at daily intakes of 50 mg in humans. Electrophysiological measurement and examination of nerve tissue confirm neuropathological changes. With the exception of the instances where especially high doses (in the order of grams) of this vitamin were ingested by some individuals, the signs of toxicity are reversible after cessation of ingestion. The lowest dose reported to have adverse effects in humans is 50 mg per day; although there are methodological deficiencies in the study showing effects at this level of intake, we consider it would be unwise to ignore this evidence in the light of other supporting human and animal data.

Recommendation

Allowing for a margin of safety between the lowest observed adverse effect level in humans and bearing in mind the supporting animal toxicity data, we recommend that the maximum daily intake of vitamin B6 from dietary supplements should be 10 mg per day.