ELAIDIC AND TRANS-VACCENIC ACIDS IN PLASMA PHOSPHOLIPIDS AS INDICATORS OF DIETARY-INTAKE OF 18 1 TRANS-FATTY-ACIDS/

Octadecenoic (18:1) trans-fatty acid fractions from margarine, butter and plasma phospholipids (PL) were isolated by silver ion TLC, and nin e positional isomers (n-11-n-3) were identified by GC-MS based on thei r ozonolysis products. The GC analysis of the isolated fractions gave similar peak profiles and separated seven trans-isomers (n-11-n-6 and n-3). Without a preceding isolation step, the reproducibility of the G C method for plasma PL elaidic (18:1 n-9 trans) and trans-vaccenic aci ds (n-7) was 3.4 and 2.7% (R.S.D.), respectively. These hans-isomers w ere rapidly incorporated and cleared in plasma PL and they closely ref lected both increased and decreased intake of 18:1 trans-fatty acids d uring moderate fat substitutions. Significant associations between hig h-density lipoprotein cholesterol (HDL-C) and PL elaidic and trans-vac cenic acids appeared in habitual margarine users only.