Meghana D. Gadgil, M.D., M.P.H., of Johns Hopkins University in Baltimore, and colleagues enrolled 164 individuals with prehypertension or stage 1 hypertension, without diabetes, in a randomized, controlled, three-period, crossover feeding study. The three diets studied were a carbohydrate-rich diet (similar to the Dietary Approaches to Stop Hypertension [DASH] diet), a protein-rich diet (predominantly from plant sources), and an unsaturated fat-rich diet (mostly monounsaturated fat). The primary outcome was calculation of the quantitative insulin sensitivity check index (QUICKI), a validated measure of insulin sensitivity.
At baseline, the researchers noted a mean body mass index of 30.2 kg/m² and a mean QUICKI of 0.35. The increase in QUICKI (0.005) was significantly greater with the unsaturated fat-rich diet compared with the carbohydrate-rich diet. The protein-rich diet had no significant effect on insulin sensitivity compared with the carbohydrate-rich diet.
“Our analysis suggests that a diet rich in unsaturated fats, which is commonplace in Mediterranean-style diets, improves insulin sensitivity in a population at risk for cardiovascular disease,” the authors write.