Trade talk

Last month I said the book Fat by Jennifer McLaggan referred to the lack of evidence for the relationship between dietary fat and cardiovascular disease.

The author contacted me to say that, although it wasn't in her book, it was a fact derived from a paper by American researchers, Paul R Marantz et al. The paper was titled A call for higher standards of evidence for dietary guidelines, published in 2008 in the American Journal of Preventative Medicine.

The authors point out that the evidence to justify US government guidelines is based on several misconceptions including the belief that 'the guidelines against dietary fat could cause no harm'. On the contrary, the authors argue that they may have led to significant and harmful unintended consequences.

The paper cannot be adequately summarised here. But, given that the Americans are ahead of Europe in this area, we ought to learn from their experience. Marantz et al point out that, although cardiovascular disease has been declining in the US, obesity has proliferated and there could be a relationship between the latter development and increased consumption of carbohydrate. This, they believe, may be partly due to growth in popularity of low-fat or fat-free foods. These need to be eaten in larger amounts to obtain the same level of satiety.

On salt guidelines, the paper cautions that the advantages of blood pressure reduction might be outweighed by harmful effects such as insulin resistance. This follows the findings of clinical trials by NR Cook et al in 2007, which reported that low sodium diets did not reduce mortality.

Marantz also warned that: 'Public health guidelines are one-size-fits-all pronouncements that fail to account for variations in genetics, behaviour, and environment.' Moreover: 'Logic and good intentions are not a substitute for solid evidence of the totality of the effects of any public health intervention.'

Those of us who believed that salt and fat control across the board would be desirable and necessary to improve human health might want to reconsider.

The paper ought to ring alarm bells at the Food Standards Agency and Department of Health. After all, they require evidence of 'no harm' when deciding whether to permit novel foods to be placed on the market.

Although a dietary guideline is not a food, if followed, it affects the overall composition and balance of an existing diet which, it may be argued, could have unknown consequences in the same way as adding a new ingredient. But government guidelines would affect far more people than putting a novel ingredient on the market. This surely justifies even greater risk assessment.

With hindsight, perhaps there are grounds for application of the precautionary principle before attempting to manipulate diet on such a large scale.

Clare Cheney

Director general of Provision Trade Federation

clare.cheney@provtrade.co.uk