[Dietary primary prevention of cardiac ischemic diseases]

Population studies have shown that ischaemic cardiopathy is more frequent in countries where the inhabitants have diets rich in saturated fats and in cholesterol, and where cholesterolaemia is raised. The epidemiological data from large prospective studies have shown that total cholesterolaemia is positively correlated with coronary risk. Therapeutic trials performed with the statins in particular have demonstrated that a reduction in LDL cholesterol allows a reduction in coronary morbidity, suggesting a causal role for cholesterol. Primary prevention dietetic trials have often been disappointing, probably due to a drop in cholesterol which is too modest, insufficient study size and duration, and perhaps also because they concerned low risk subjects. A meta-analysis of 27 primary and secondary prevention dietetic studies produced evidence of a reduction in morbidity, principally when the studies lasting less than 2 years were not taken into account. In this meta-analysis the drop in cholesterol was correlated with a reduction in clinical events. The benefit of a modified fat diet in primary prevention is therefore potentially significant if it is maintained for a sufficient length of time. The very positive results of the American national programme of nutritional intervention, which has had an undeniable impact on the prevalence of lipid disorders in the general population and secondarily on coronary mortality, favours the continuation of this mode of prevention.