High Olive Oil vs. High Safflower Oil Diets Produce Different Metabolic Abnormalities in Rats

Abstract

Olive oil (~72% monounsaturated fat) and safflower oil (~78% ω‐6 polyunsaturated fat) are regarded as healthful by the general public. To assess the effects of high intakes of these oils, we fed male Sprague Dawley rats ad libitum diets containing 55% of energy as olive oil (OHF, N=20) or safflower oil (SHF, N=20), using a 15% fat diet as the control (LF, N=20), for 8 wk. OHF and SHF rats exhibited similar energy intakes throughout the study. At wk 8, % body fat of the HF groups similarly exceeded those of the LF group (OHF~SHF > LF, p < 0.01 ).Plasma glucose levels after fasting, or after a high‐carbohydrate meal, were similar in all groups. At wk 8, fasting plasma insulin levels were higher in OHF than SHF or LF rats (p< 0.01) and HOMA‐IR was higher in OHF vs. SHF rats (p<0.05), evidencing insulin resistance in the OHF group. Plasma insulin levels increased in LF and SHF (p < 0.005) but not in OHF rats following the high‐carbohydrate meal, reflecting a blunted insulin secretory response to glucose in OHF rats. Fasting free fatty acid (FFA) levels were higher in LF than in OHF or SHF rats (p < 0.05); following insulin injection ( 0.75 U/kg), FFA levels decreased in the LF and OHF groups (p < 0.005), but increased in SHF rats (p < 0.05), indicating a diminished antilipolytic effect of insulin on adipose tissue in the SHF group. These findings suggest that high intakes of olive oil impair the regulation of insulin release and its effect on plasma glucose levels, whereas high intakes of safflower oil impair suppression of lipolysis by insulin.Support or Funding InformationNIGMS 1SC3GM086298 PSC‐CUNY 6783300‐45