Normal endothelial function after meals rich in olive or safflower oil previously used for deep frying

Background and Aim: Polyunsaturated fats are more susceptible to oxidation during heating than monounsaturated fats but their effects on endothelial f unction when heated are unknown. The aim of this study was to compare the e ffect of meals rich in heat-modified safflower and olive oils on postprandi al flow-mediated endothelium-dependent dilation (EDD) in healthy men. Methods and Results: Flow-mediated EDD and glyceryl-trinitrate-induced endo thelium-independent dilation of the brachial artery were investigated in 14 subjects before and 4 hours after meals rich in olive oil and safflower oi l used hourly for deep-frying for 8 hours in a double-blind crossover study design. There were high levels of lipid oxidation products (peroxides and carbonyls) in both heated oils. Plasma triglycerides were markedly increase d at 4 hours after heated olive oil (1.26 +/-0.43 vs 2.06 +/-0.97 mmol/L) a nd heated safflower oil (1.44 +/-0.63 vs 1.99 +/-0.88 mmol/L). There was no change in EDD between fasting and postprandial studies and the response du ring the postprandial period was not significantly, (p=0.51) different betw een the meals (heated olive oil: 4.9 +/-2.2% vs 4.9 +/-2.5%; heated safflow er oil: 5.1 +/-3.1% vs 5.6 +/-3.4%). Conclusions: Meals rich in olive and safflower oils previously used for dee p frying and containing high levels of lipid oxidation products increase po stprandial serum triglycerides without affecting endothelial function. Thes e findings suggest that relatively short-term use of these vegetable oils f or frying may not adversely affect postprandial endothelial function when f oods containing the heat-modified oils the consumed. (C) 2001, Medikal Pres s.