[Trans fatty acids: effects on lipoprotein metabolism and cardiovascular risk].

Dietary trans fatty acids (TFA) (mainly 18:1 isomers) have two sources: they are formed during the natural bacterial hydrogenation of unsaturated fatty acids in ruminants or they come from the industrial hydrogenation of unsaturated vegetable oils. Total trans fatty acids account for 1.3% of total energy intake in France compared to 2-3% in USA. Recent epidemiologic studies and meta-analyses of well-designed controlled trials clearly showed that trans fatty acids are associated with an increase of cardiovascular risk. It seems that TFA from industrial sources are responsible for the deleterious effects particularly on lipoprotein metabolism. Specifically the consumption of industrial TFA has been associated with high plasma concentrations of triacylglycerols, LDL-cholesterol and small dense LDL and lower HDL-cholesterol concentrations. The very recent interventional trials allowed for a comparison of TFAs from different sources suggest that the intake of natural TFA have no or neutral effects on plasma lipids and other cardiovascular risk factors. However, the mechanisms underlying the isomer-specific effects are not well understood and warrant further investigations.