[Trans-fatty acids and health].

Trans fatty acids are formed by partial hydrogenation of vegetable and marine oils or by bacterial activity in the rumen of ruminants. Main dietary sources are margarine, meat, milk fat and bakery products. Unsaturated fatty acids in the trans form have a more straight structure than their cis counterparts. They therefore have properties more like saturated fatty acids. Trans fatty acids may compete with essential fatty acids for elongating and desaturating enzymes and thereby interfere in the formation of eicosanoids. Trans fatty acids in the diet will increase LDL-cholesterol but to a lesser degree than the saturated fatty acids C12-C16. They also decrease HDL-cholesterol and increase Lp(a). By these unfavorable effects on blood lipids it may be expected that they will increase the risk of coronary heart disease. This has been confirmed in some, but not all, epidemiological studies. Provided the diet contains sufficient amounts of essential fatty acids there are no strong indications that trans fatty acids may have other unfavorable effects on health. Over time the intake of trans fatty acids has decreased considerably in Norway (from a mean of about 15 g/day in 1958 to about 4 g/day actually). The health effects of such an intake must be considered minor compared to an eight to ten fold higher intake of saturated fatty acids.