The coronary benefit of polyunsaturated fat (PUFA) replacing saturated fat (SFA) in the diet is largely attributed to the reduction in LDL-cholesterol that occurs as a result. However, new research suggests that the benefit of PUFA isn’t limited to this one metric as a recently published meta-analysis found pronounced benefits of PUFA on glycemic control. This analysis involved 102 controlled trials, including 239 diet arms and 4,220 adults. Using multiple-treatment meta-regression, the dose-response effects of isocaloric replacements between SFA, monounsaturated fat (MUFA), PUFA and carbohydrate, adjusted for protein, trans fat, and dietary fiber were estimated.
Key findings include the following 1) replacing carbohydrate with PUFA significantly lowered glycosylated hemoglobin and fasting insulin and 2) replacing SFA with PUFA significantly lowered glucose, glycosylated hemoglobin, C-peptide and insulin resistance and 3) PUFA significantly improved insulin secretion capacity whether replacing carbohydrate, SFA or MUFA.
Not surprisingly, given the above findings, the authors of this analysis concluded that their meta-analysis “provides evidence that dietary macronutrients have diverse effects on glucose-insulin homeostasis. In comparison to carbohydrate, SFA, or MUFA, most consistent favourable effects were seen with PUFA, which was linked to improved glycaemia, insulin resistance, and insulin secretion capacity.”
Imamura F, Micha R, Wu JH, de Oliveira Otto MC, Otite FO, Abioye AI, and Mozaffarian D. Effects of saturated fat, polyunsaturated fat, monounsaturated fat, and carbohydrate on glucose-insulin homeostasis: A systematic review and meta-analysis of randomised controlled feeding trials. PLoS Med 2016;13:e1002087.