Vitamin D--Time for Reassessment

It is a fact of life in the current scientiŽ c world that publicity, hype, and spin are more important in spreading information—and disinformation—about nutritional medicine than peer-reviewed scientiŽ c studies. The recent publicity over vitamin C is an obvious instance of this; a paper from the University of Pennsylvania Center for Cancer Pharmacology was the subject of a press release that presented it as new data that may have shown a damaging effect of vitamin C, even though any number of other studies have shown the opposite. When the principal author, Ian A. Blair, was Ž nally contacted by telephone (the press release was issued while he was out of the USA on holiday), he apparently said ‘Absolutely for God’s sake don’t say vitamin C causes cancer’. This did not stop the media from reporting exactly that, with the result that many patients world-wide have been stopping or reducing their vitamin C intake, with possible detrimental effects on health. As has been pointed out repeatedly, if the study had shown a positive effect from vitamin C, or any other nutrient, experience tells us that it would not have been ‘hyped up’ in this manner. Which is also exactly what did not happen with a crucial review article on vitamin D in the American Journal of Clinical Nutrition in 1999 [1]. This paper, by Dr Reinhold Vieth in Toronto, laid out strong arguments that we are all deŽ cient in vitamin D, because we have grossly misjudged the necessary intake for adults and the amount needed to cause toxicity. Since then Dr Veith has continued to accumulate evidence of this, his central thesis, and for the further ramiŽ cations of it. In this issue he brings the argument up to date [2] and discusses the implications, not just for bone health, but for a number of other diseases as well. Ironically, this comes at a time when the US Environmental Protection Agency is advising that ultraviolet light, and therefore sunlight, is so dangerous that we should ‘protect ourselves against ultraviolet light whenever we can see our shadow’. Following this advice is likely to lead to an increase in vitamin D deŽ ciency diseases, and is effectively discriminatory against the many individuals with darker skin types who now live in higher latitudes. As a physician who has seen two cases of rickets this year, I Ž nd this of great concern. Whether sunlight is the direct and principal cause of skin cancers and other skin damage is a separate debate, which we cannot cover here, but the evidence is mounting that following current guidelines on sun protection will have detrimental effects on other areas of health. There are several important, only recently understood, and not yet widely appreciated, points to be made about vitamin D: