The e †ect on food intake, weight gain, liver lipid peroxides, lipemia and lipoprotein composition was determined in rats fed a diet with 15% sunÑower oil used repeatedly for frying and containing D19% polar material (group 2). These dietary e †ects were compared over a 4 week study period with those found in rats fed a control diet that contained 15% unused sunÑower oil with D5% polar material (group 1). Both groups had similar food and nutrient intakes (except for linoleic acid, signiÐcantly lower (P \ 0É01) in group 2), yet the Ðnal weight gain and food efficiency and protein efficiency ratios were signiÐcantly lower in group 2. As a consequence of thermoxidised oil ingestion, liver homogenates from group 2 presented higher (P \ 0É02) levels of thiobarbituric acid reactive substances (TBARS) Liver TBARS levels were signiÐcantly correlated (P \ 0É01) with the amount of thermoxidised substances ingested. No treatment e †ect was found on VLDL lipid composition. However, the LDL fraction of group 2 animals appears enriched (P \ 0É05) in total and free cholesterol. In group 2 rats, phospholipids, and total and esteriÐed cholesterol were signiÐcantly increased (P \ 0É05) in HDL. As a consequence of the changes in the lipoprotein composition, the amount of all forms of serum cholesterol, and serum phospholipids was signiÐcantly higher (at least P \ 0É05) while the amount of serum triacylglycerols remained unchanged in rats fed the used oil. HDL-phospholipids were signiÐcantly correlated (P \ 0É02) with the amount of thermoxidised compounds ingested. The increase in serum cholesterol and phospholipids, and in HDLcholesterol and HDL-phospholipid concentration seens in group 2 rats may be a protective mechanism against the peroxidative stress produced by the ingestion of used sunÑower oil.
1998 SCI.