On Diet Again

Food is fuel for the body and so we have to get our energy from somewhere. Leaving protein aside we can consume sugar (bad, especially in ‘free’ form [1]), polyunsaturated fats in vegetable oils (good), or saturated fats (okay – well not nearly as harmful as previously thought [2]). Then there are trans-fats. Rarely found in nature, these manufactured fats are pure bad. Fats contain long hydrocarbon chains. Changes to these chains completely change the physical characteristics of the fat and its health effects. Carbon atoms in the chain can be joined to each other by a double or a single bond. In the latter case, linkage to a hydrogen atom replaces the second linkage to a carbon atom. If just once carbon atom is linked to a hydrogen atom, the fat is referred to as unsaturated and its physical properties change. However, a very subtle change in the orientation of the hydrogen atom in three-dimensional space yields non-subtle changes in the health effects of the unsaturated fat. In the natural fat, the hydrogen occupies one orientation (cis), and it is healthy. But in manufactured fat it occupies the alternative (trans) orientation, and it is bad – pure bad!

The question is not whether trans-fats are bad, but what to do about it. In individual terms – eschew them! But in policy terms, should we nudge, advise, exhort, shame, or should we coerce by phasing in a ban? A recent BMJ paper [3] models the effects of each policy. The ban saves more lives than less coercive policies. The CLAHRC WM Director is a libertarian, and does not like coercion. On the other hand, trans-fats are devoid of merit – there is no real trade-off, unlike say carbon fuels, alcohol, areca nut, hang-gliding, gambling, and lots of other things that at least some people like. To put this another way, people who consume trans-fats can’t really be said to be choosing them – so let’s ban the bloody things!

— Richard Lilford, CLAHRC WM Director


  1. Lilford R. How Much Sugar is too Much? September 25 2015.
  2. Lilford R. More on Diet. August 14 2015.
  3. Allen K, Pearson-Stuttard J, Hooton W, et al. Potential of trans fats policies to reduce socioeconomic inequalities in mortality from coronary heart disease in England: cost effectiveness modelling study. BMJ. 2015; 351: h4583.

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