Overweight/obesity, CVD and type 2 diabetes are strongly associated with nutritional habits. High consumption of fried foods might increase the risk of these disorders. However, it is not clear whether the use of vegetables oils for cooking increases the risk of chronic diseases. We systematically searched for published studies that assessed the association between vegetable oil consumption including fried food consumption and the risk of overweight/obesity or weight gain, T2DM or the metabolic syndrome, and CVD or hypertension in the following databases: PubMed; Web of Science; Google Scholar. Keywords such as 'fried food' or 'vegetable oil' or 'frying' or 'frying oils' or 'dietary fats' and 'weight gain' or 'overweight' or 'obesity' or 'CHD' or 'CVD' or 'type 2 diabetes' or 'metabolic syndrome' were used in the primary search. Additional published reports were obtained through other sources. A total of twenty-three publications were included based on specific selection criteria. Based on the results of the studies included in the present systematic review, we conclude that (1) the myth that frying foods is generally associated with a higher risk of CVD is not supported by the available evidence; (2) virgin olive oil significantly reduces the risk of CVD clinical events, based on the results of a large randomised trial that included as part of the intervention the recommendation to use high amounts of virgin olive oil, also for frying foods; and (3) high consumption of fried foods is probably related to a higher risk of weight gain, though the type of oil may perhaps modify this association.
Keywords: CVD; Fried foods; Hypertension; Metabolic syndrome; Obesity; Olive oil; Type 2 diabetes mellitus.