An isomeric mixture of conjugated linoleic acids but not pure cis-9, trans-11-octadecadienoic acid affects body weight gain and plasma lipids in hamsters.

We report the effect of an atherogenic diet supplemented with cis-9, trans-11-octadecadienoic acid (c9t11), linoleic acid (LA) or an isomeric mixture of conjugated linoleic acids (CLA) on plasma lipids, weight gain and food intake of male Golden Syrian hamsters. Animals were assigned to three diet groups (n = 10), and fed nonpurified diet, supplemented with 10% hydrogenated coconut oil and 0.05% cholesterol for 6 wk. The first diet group was further supplemented with 1% CLA (CLA group), the second diet group with 0.2% c9t11 (c9t11 group) and the third group with 0.2% LA (LA group). The diets were designed to have equivalent levels of c9t11 in the CLA and c9t11 groups. At 2 and 6 wk of feeding, the CLA group had significantly lower plasma triglyceride and total cholesterol concentrations than either the c9t11 or the LA groups. HDL-cholesterol did not differ among diet groups. The CLA group had significantly lower weight gain but greater food intake than either the c9t11 or the LA groups. There were no significant differences between the c9t11 and the LA groups in any of the variables measured. We conclude that under our experimental conditions of short-term feeding, c9t11, thought to be the active compound in CLA, does not produce the same effect as the isomer mixture.