Consumption of hydrogenated versus nonhydrogenated vegetable oils and risk of insulin resistance and the metabolic syndrome among Iranian adult women.

R emarkably rapid increase in the prevalence of the metabolic syndrome reflects the strong impact of lifestyle factors, including diet, on its etiology. In particular, dietary intake of fat may play a role in this regard. Different types of fat have been related to insulin resistance and the metabolic syndrome, but findings are inconsistent. One specific type of dietary fatty acid that has received increased attention is trans fatty acid (TFA); higher consumption was associated with increased risk of cardiovascular disease (1) and type 2 diabetes (2). Although some studies have reported a significant association between dietary fat intake and the metabolic syndrome (3,4), to our knowledge, such analyses have not been done separately for hydrogenated and nonhydrogenated vegetable oils. Hydrogenated vegetable oils (HVOs)—rich sources of both saturated fatty acids (SFAs) and TFAs—are extensively used for cooking in Iranian homes with average per-person intake of 14g per 1,000 kcal (5). In addition to large amounts of SFAs, these products have almost 33% of total fatty acids as TFAs. In other words, 4.2% of all calories consumed by Iranians are derived from TFAs, which is about twice the amount consumed in many developed countries (5). In the current study, we investigated whether high consumption of HVOs is contributing to a high prevalence of the metabolic syndrome among Iranian women.