Abstract 003: Effects of Saturated, Polyunsaturated, and Monounsaturated Fat on Blood Glucose, Insulin Sensitivity, and 2 Cell Function: A Systematic Review and Meta-analysis of 84 Randomized Controlled Feeding Trials
Background: Effects of saturated fat (SFA), monounsaturated fat (MUFA), and polyunsaturated fat (PUFA) on blood glucose, insulin sensitivity (IS), and β cell function are not well established.
Aim: To systematically quantify the effects of dietary fats on glucose homeostasis in randomized controlled feeding trials (RCTs).
Methods: Using PRISMA guidelines, we systematically searched 11 databases for RCTs testing effects of isocaloric diets of varying dietary fat composition on glucose-insulin metrics in adults. We excluded RCTs of supplements or diet advice rather than provision of diets. Data were extracted independently and in duplicate. Using multivariate meta-regression, we estimated dose-response effects of isocaloric exchange of major macronutrients (SFA, MUFA, PUFA, carbohydrate [CHO]), adjusting for protein and fiber, and assessed heterogeneity (α=0.001 adjusted for multiple testing) by prespecified factors.
Results: Of 3,661 identified abstracts, 84 RCTs met inclusion criteria, comprising 195 diet arms in 4,837 adults (19-74 y). Replacing CHO with SFA raised fasting glucose (FG), while MUFA and PUFA lowered FG (Table). Findings were concordant for HbA1C. Effects on FG were strongest in diabetics and Asians (P interaction<0.001 each); interactions for HbA1c were not statistically significant. Significant effects were not seen on IS or β cell indices by intravenous tests, although fewer RCTs evaluated such tests.
Conclusions: SFA raises, while MUFA and PUFA reduce FG and HbA1c. Effects are stronger in diabetics and Asians. Our meta-analysis provides robust quantitative evidence on effects of major dietary fats on glucose-insulin metrics, directing further research and dietary guidelines.
- © 2013 by American Heart Association, Inc.