The proportion of trans monounsaturated fatty acids in serum triacylglycerols or platelet phospholipids as an objective indicator of their short-term intake in healthy men.

Unfavourable effects of trans monounsaturated fatty acid (trans-C18:1) isomers on health variables have been reported. Reports on their actual intake, however, are scarce, because of the absence in many nutrient databases of values for trans-C18:1, and the wide variation in the level of trans fatty acids between different brands of the same product. We therefore examined whether the intake of trans-C18:1 is reflected by trans-C18:1 concentrations in serum triacylglycerols or platelet phospholipids. Thirty-eight men received two diets in random order. During the first experimental period twenty men consumed a Western-type control diet for six weeks, and eighteen men consumed a modified diet in which 70% of the fat was replaced by palm oil. After a wash-out period of 3 weeks, regimens were crossed over (second experimental period). The proportion of total fatty acids from trans-C18:1 in the diet decreased from 4.7 (SEM 0.27) during the control to 2.1 (SEM 0.16) on the modified diet (P < 0.001). Trans-C18:1 in serum triacylglycerols decreased from 3.5 (SEM 0.13) to 2.8 (SEM 0.11)% (P < 0.001), and in platelet phospholipids from 1.0 (SEM 0.06) to 0.7 (SEM 0.04)% (P < 0.001). After the first experimental period trans-C18:1 in the diet correlated with trans-C18:1 in serum triacylglycerols (r 0.41; P = 0.014), and platelet phospholipids (r 0.52; P = 0.001). Also, differences in the intake between the two periods correlated with changes in the proportion of trans-C18:1 in serum triacylglycerols (r 0.56; P = 0.001) and platelet phospholipids (r 0.58; P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)