Fall in coronary heart disease mortality in U.S.A. and Australia due to sudden death: evidence for the role of polyunsaturated fat.

Epidemiological studies have been reviewed which provide suggestive evidence of an association between the fall in coronary heart disease mortality in the U.S.A and Australia since 1967, characterized by a fall in sudden deaths, to the increase in polyunsaturate fat consumption that has occurred in both countries since 1960. This association led directly in the same institution to carefully designed experimental studies undertaken in the rat, and a non-human primate, the marmoset (Callithrix jacchus jacchus) with a heart and lipid metabolism more closely resembling that of man. In both animal species, a vegetable fat diet had a protective effect against the increase in contractility of isolated papillary muscles induced by age, the addition of animal fat, or by isoprenaline in vitro. Similar effects were observed following coronary artery ligation, where the extent of dysrhythmia was greatly reduced by supplementing the diet with a linoleic acid rich vegetable oil. It is concluded that the combination of epidemiological and experimental evidence indicates a protective effect of dietary polyunsaturates against sudden cardiac death. This work illustrates the value of the integration of epidemiological and experimental approaches to the aetiology of disease.