Effects of dietary canola, olive, and linolenic acid enriched olive oils on plasma lipids, lipid peroxidation and lipoprotein lipase activity in rats

This study investigated the effect of alpha-linolenic acid enriched virgin olive, canola and virgin olive oil on body composition, serum lipids, lipid peroxidation and adipose tissue lipoprotein lipase activity in rats. Twenty six male Sprague Dawley rats were fed ad-libitum three diets, containing 40% of dietary calories from fat being either canola (CO), virgin olive (VO), or alpha-linolenic acid enriched virgin olive oil (LO) for seven weeks. At the end of feeding period, the rats were killed by decapitation and blood samples were analyzed for serum triglycerides (TG), total and HDL-Cholesterol (TC and HDL-C), glucose, insulin, malondialdehyde (MDA) and 4-hydroxy-2(E)-nonenal (4-HNE). Carcasses were analysed for water, fat, and protein content. Individual fat pads were dissected out and weighed. Fat cell size and number, and adipose tissue lipoprotein lipase activity were determined. Results showed that serum triglycerides levels were lower in the CO and LO as compared to VO group. Total plasma cholesterol levels were not different between the CO and LO group but were significantly lower than the VO group. The alpha-linolenic acid enrichment of VO seems to mimic the effect of CO on blood lipids, and hence could be responsible for reducing triglycerides and total cholesterol, and increasing HDLC/total cholesterol ratio when compared to VO. Feeding CO, resulted in significantly lower 4-HNE levels as compared to VO and LO. The effects of alpha-linolenic acid may be explained by its conversion into eicosapentaenoic acid (EPA), which has been previously reported to produce the same effects on plasma lipids. Further studies are needed to elucidate other possible mechanisms of action of alpha-linolenic acid on the atherogenic factors. (C) 1999 Elsevier Science inc.