Trans isomers of oleic and linoleic acids in adipose tissue and sudden cardiac death

Abstract

Trans isomers of unsaturated fatty acids are formed by biological or industrial hydrogenation. A population case-control study of sudden cardiac death in men was done to test the hypothesis that trans isomers of oleic acid and linoleic acid increase the risk of sudden cardiac death due to coronary artery disease. In adipose tissue obtained at necropsy from 66 cases of sudden cardiac death and taken from 286 healthy age and sex matched controls, the proportions of trans isomers of oleic and linoleic acid were measured by gas-liquid chromatography. In cases, the mean (SE) percentage of total trans fatty acids (C18:1 plus C18:2), expressed as a proportion of all fatty acids, was significantly lower (2·68 [0·08]%) than in healthy controls (2·86 [0·04]%; p<0·05). Trans C18:1 was 2·1 (0·7)% in cases compared with 2·27 (0·04)% (p<0·05) in controls. The proportion of all trans isomers of linoleic acid was 0·58 (0·02)% in cases compared with 0·59 (0·01)% in controls (p=0·98). The estimated relative risk for sudden cardiac death of trans C18:1 and C18:2 fatty acids combined did not differ significantly from 1·0 in relation to the distribution of these trans isomers by quintile in the control population. The relative risk (95% Cl) of sudden cardiac death in the top quintile was 0·40 (0·15-1·02) for C18:1 and 1·08 (0·48-2·74) for C18:2 compared with the bottom quintiles of their respective control distributions. When these univariate relations for trans fatty acids were adjusted for coronary risk factors, smoking was the only factor that remained independently associated with risk of sudden cardiac death (2·27 [1·23-4·17]). Overall, there was no evidence of a relation between trans isomers of oleic and linoleic acids combined and sudden cardiac death. However, trans oleic acid was negatively associated with risk of sudden cardiac death, whereas no association with trans forms of linoleic acid was seen. This study does not support the hypothesis that trans isomers increase the risk of sudden cardiac death.