Impact of Heated Versus Unheated Cooking Oil on Postprandial Vascular Function and Metabolism

ABSTRACT The impact of repeated heating of seed‐based culinary oils on cardiometabolic health has not been well established. Heating oils to high temperatures (> 150°C) causes lipid peroxidation, thus generating potentially harmful compounds that may impair vascular function. This randomized, single‐blind, crossover study investigated the acute effects of a high‐fat meal containing either repeatedly heated (at 180°C, over 10 days, with 5 potato fries per day) sunflower oil‐palm olein blend, compared with an unheated blend (containing 23.8% and 7.2% polar compounds respectively), on postprandial lipids and vascular function in 19 healthy male participants. Participants consumed each test meal on separate days, with measurements of flow‐mediated dilation (FMD; primary outcome), arterial stiffness, plasma triacylglycerol (TAG), non‐esterified fatty acid (NEFA), and glucose concentrations over 4 h. Postprandial vascular (FMD and arterial stiffness) responses as well as NEFA and glucose concentrations were comparable between meals. The postprandial TAG increase was lower after heated versus unheated oil ( p < 0.001). These findings indicate that repeated heating of oil modifies postprandial lipaemia without acutely impairing vascular function. However, these short‐term results do not address the potential cumulative effects of chronic, long‐term consumption.