Adipose tissue n-6 fatty acids and acute myocardial infarction in a population consuming a diet high in polyunsaturated fatty acids

The Jewish population of Israel consumes a diet rich in n-6 polyunsaturated fatty acids (PUFAs), principally linoleic acid. The consequences of this diet for ischemic heart disease (IHD) remain unclear. We assessed the association of adipose tissue n-6 fatty acids, which are derived entirely from the diet, with acute myocardial infarction (AMI). A total of 180 cases and 492 IHD-free controls aged 25-64 were included in a population-based case-control study of Jerusalem residents hospitalized with a first AMI. Diet was assessed by the use of a food-frequency questionnaire and adipose tissue fatty acids by gas chromatography of biopsy samples taken from subcutaneous gluteal tissue. The data were analyzed by multivariate logistic regression. Dietary PUFAs (: 10.1% of energy) correlated (r = 0.43, P < 0.001) with adipose tissue linoleic acid, which constituted 25.6% of storage fatty acids. High intakes of linoleic acid were not associated with excess risk of AMI (age- and sex-adjusted odds ratio for the third versus the first tertile: 0.96; 95% CI: 0.62, 1.48; NS). In contrast, arachidonic acid, the long chain n-6 derivative of linoleic acid, was positively associated with AMI (age- and sex-adjusted odds ratio: 2.12; 95% CI: 1.33, 3.36; P = 0.004). With multivariate adjustment, there was no evidence for an adverse association of linoleic acid with AMI, whereas the risk associated with arachidonic acid persisted, albeit attenuated. A very high linoleic acid intake does not appear to confer increased risk of nonfatal AMI. Nonetheless, the increased risk associated with arachidonic acid, a finding that requires confirmation, tempers an inference that diets rich in n-6 fatty acids are safe vis-à-vis coronary health.