Intended for healthcare professionals

Letters

Vitamin B-6

BMJ 1999; 318 doi: https://doi.org/10.1136/bmj.318.7181.463 (Published 13 February 1999) Cite this as: BMJ 1999;318:463

Many have found relief from disorders for which no effective treatment exists

  1. J Marks, Fellow
  1. Girton College, Cambridge CB3 0JG
  2. Vitamin B6 Scientific Task Group, 73 Endowood Road, Sheffield, South Yorkshire S7 2LY

    EDITOR—Collier is right that the border between nutritional and medical uses of vitamin B-6 is blurred and needs fresh examination.1 It is therefore disappointing to note that a number of members of the Committee on Toxicity of Chemicals in Food, Consumer Products, and the Environment, whose report on pyridoxine was so roundly rejected by the Commons Agriculture Select Committee, will now sit on the new expert group on vitamins and minerals.2

    However, I disagree with Collier on two specific points. Firstly, submissions to the Commons committee clearly showed that there is no scientific evidence that neuropathy results from the prolonged use of pyridoxine in doses of less than 500 mg/day.3 Whatever Dalton and Dalton observed, it was clearly not pyridoxine neuropathy.4 Secondly, I believe that Collier's “centralist and restrictive” approach to the control of pyridoxine runs contrary to the widely held view that individuals should be responsible for their own health and should be given the best available information on which to base their decisions. Few would argue that scientific proof of activity for high doses of pyridoxine is not available. However, it is clear that pyridoxine is safe at doses of 100-200 mg, which is the dose at which it has been used, and that this dose is mainly used for self medication in disorders for which there is no effective alternative treatment. The data submitted to the agriculture committee showed that there are tens of thousands of people who have found relief by using pyridoxine—relief which may, admittedly, be due in part or entirely to a placebo effect.

    References

    Government guidelines are not based on scientific evidence

    1. Arnold Beckett, Chairman
    1. Girton College, Cambridge CB3 0JG
    2. Vitamin B6 Scientific Task Group, 73 Endowood Road, Sheffield, South Yorkshire S7 2LY

      EDITOR—Collier's editorial on guidelines for the availability of vitamin B-6 does more to obfuscate than to clarify the issue.1 The government has stated that “supplements containing high doses of vitamins and minerals should continue to be available under food law except where they may pose a risk to health.”2 The issues of need and efficacy raised by Collier are therefore irrelevant and diversionary. The issue is solely whether vitamin B-6 at the doses currently used is safe.

      The government has repeatedly asserted that the recommendation that vitamin B-6 be limited to a maximum of 10 mg/day, made by the Department of Health's Committee on Toxicity of Chemicals in Food, Consumer Products, and the Environment, is based on the “totality of the scientific literature,” maintaining that the committee “considered over 100 scientific papers from national and international journals, of which the study by Dalton and Dalton was only one” (joint statement by the Ministry of Agriculture, Fisheries, and Food and the Department of Health, 21 August 1997). However, the committee's chairman, Professor H F Woods, has now admitted that “the only human evidence that was relied upon was that contained in the Dalton and Dalton study.”2 Indeed, it couldn't be otherwise, because the study by Dalton and Dalton is the only one that questions the safety of dosages currently used in the United Kingdom—that is, up to 200 mg/day.

      The Dalton and Dalton study, which has been severely and repeatedly denigrated in the literature,2 has recently been explicitly discounted by the US National Academy of Sciences.4 In appraising this study, Collier states that “it seems inescapable that with such large numbers some women will indeed have developed neuropathy at these low doses.” In no way is such a conclusion “inescapable.” Symptoms such as paraesthesia, hyperaesthesia, weakness, and numbness are not uncommon in the general population, particularly in women with premenstrual tension. To ascribe such symptoms to neuropathy in the absence of objective neurological testing is unwarranted. Investigators who have used neurological testing have found vitamin B-6 to be entirely free from neurotoxicity at the dosages under discussion.2

      It is a matter for concern that the government could countenance, let alone implement, legislation based on a patently spurious premise. Our politicians seem to be unaware of the fact that their “expert” advisers are operating far from the ethical standards they imagine.

      References

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