“Nutritionists are alternative therapists, but have somehow managed to brand themselves as men and women of science. Their errors are much more interesting than those of the homeopaths, because they have a grain of real science to them, and that makes them not only more interesting, but also more dangerous, because the real threat from cranks is not that their customers might die – there is the odd case, although it seems crass to harp on about them – but that they systematically undermine the public’s understanding of the very nature of evidence.”