SERUM-LIPID RESPONSES TO SIMULTANEOUS ALTERATIONS IN DIETARY PALMITICAND OLEIC ACIDS IN THE ABSENCE AND PRESENCE OF DIETARY-CHOLESTEROL INTHE HAMSTER

Three separate studies, each of B-week duration, were carried out to a ssess the effects of simultaneously lowering palmitic acid (PA) and in creasing oleic acid (OA) levels in the diets on serum lipid responses in the absence and in the presence of dietary cholesterol in the hamst er. Our results show that in the absence of dietary cholesterol, refin ed, bleached and deodorized palm oil (RBDPO), a new hybrid crude palm oil (HBCPO) and olive oil (OLO) produced similar serum lipid responses in the hamster. In the presence of low level (0.05%,w/w) of dietary c holesterol, RBDPO, HBCPO, OLO and high-oleate sunflowerseed oil (HOSFL O) again produced no difference in serum lipid responses. Since RBDPO and HBCPO are high in PA and OLO and HOSFLO are high in OA, the above results indicate that PA and OA have similar nonhypercholesterolemic e ffect in cholesterol-free and low cholesterol dietary conditions. Howe ver, in the presence of high level (2%,w/w) of dietary cholesterol, OL O and HOSFLO lowered serum total. cholesterol level significantly (P<0 .05) than RBDPO and HBCPO. High density lipoprotein cholesterol (HDL-C ) level was not significantly affected. Serum triacylglycerol (TAG) le vels in the RBDPO and HBCPO groups were much higher than that of OLO a nd HOSFLO groups; but due to large standard deviations, statistical si gnificance was not achieved. Our results further show that serum TAG l evels in all four dietary groups were raised more than two-fold in the presence of low level of dietary cholesterol as compared to that seen in the absence of dietary cholesterol. Moreover, further increase in dietary cholesterol had no positive effect on the serum TAG level. Res ults from these studies show that PA and OA exhibited non-hypercholest erolemic effect in the absence and presence of low level of dietary ch olesterol in the hamster, and PA exhibited hypercholesterolemic effect while OA showed hypocholesterolemic effect in the presence of high le vel of dietary cholesterol.