Science - September 10, 2009

Letters: Antioxidants & Hofstede bows out

Should we or shouldn't we be taking those pills?

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Antioxidants
Ellen Kampman, professor of Nutrition and Cancer, advised us in Resource of 27 Augustus to ‘ignore antioxidant food supplements’. This comes in the wake of findings of an in vitro study published in Nature and is also based on her ‘guess that these supplements might have a negative effect.’
This advice seems rash, to say the least. In any case, the standards to which possible deficiencies are related – the recommended daily intake (RDI) – are incomplete and out-of-date. Most of the recommendations date from the 1940s. As an example, the Health Council advised the government in 2008 to increase the RDI of Vitamin D for older men and women by four times. This implies that these values could not have been reached without supplements.
Moreover, a general advice is untenable, since health is a personal matter, differing greatly from one person to the other. Whether you lack something or not can only be established by (blood) tests. This is better illustrated in an article about the antioxidant zinc in the August issue of the American Journal of Clinical Nutrition. The researchers concluded: ‘Zinc deficiency is estimated to affect 2 billion people worldwide, and is believed to elevate the risk of several chronic diseases, including cancer. The ability of zinc to increase DNA repair, in addition to its role as an antioxidant, may be responsible for its protective effect.’
Wim Zeegers
 
Response
The heated discussion about nutritional supplements that had blown up in response to the article in Nature shows how emotionally loaded this subject is. No other topic in the field of nutrition has generated such a variety of opinions – or, unfortunately, so many sacred cows.  Commercial parties play an interesting role in this. We shall continue to plead for solid scientific evidence. For the consumer it is already extremely confusing. Or example, the vitamin D mentioned by Mr. Zeegers is not an antioxidant, and zinc is a mineral with various functions. Wageningen colleagues have played a key role in the advice to give vitamin D supplements to some elderly people and immigrants (for example those who wear veils). The same goes for folic acid for women wanting to get pregnant. But in the case of antioxidants and tumours, our advice will remain negative until there is evidence to the contrary.
Ellen Kampman, professor of nutrition and cancer
Renger Witkamp, professor of nutrition and pharmacology  
 
Hofstede’s farewell: Sweat and brimstone
Thank you, dear readers of my column, for all your praise, comments and suggestions. How different that was, compared to the usual life of a scientist, who constantly gets to hear or read about things in his texts which are not right. Yet I will henceforth just dip my pen into the sweat of the scientist’s lot, and leave the vitriol of the columnist to someone else. Resource, keep going!
Gert Jan Hofstede

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