EDITOR, - At their core the papers by M R Law and colleagues are about the advisability of reducing the cholesterol concentration in the general population, principally through restriction of dietary fat.*RF 1-3* This primary prevention mandate is plagued by controversies, while consensus exists for lowering cholesterol in patients with coronary heart disease. What, then, do the papers add to the issues surrounding population based dietary treatment to lower serum cholesterol concentrations?

With respect to evidence that a low cholesterol concentration is associated with increased mortality from causes other than coronary heart disease Law and colleagues emphasise that these relations are seen exclusively in community based populations rather than in (typically smaller) cohorts based on occupation. They assert that illness present at entry to community based studies caused a fall in cholesterol concentrations. The authors fail to recognise, however, that the largest “community based” cohort was in fact recruited primarily from employee groups.4 Moreover, no evidence is presented that more illness existed in community samples, that these conditions preceded a fall in cholesterol concentration in people healthy enough to volunteer for participation, and that such illnesses account for the associations with mortality. Quantitative attempts to …