Effects of immediate‐release niacin and dietary fatty acids on acute insulin and lipid status in individuals with metabolic syndrome

Abstract

BACKGROUND The nature of dietary fats profoundly affects postprandial hypertriglyceridemia and glucose homeostasis. Niacin is a potent lipid‐lowering agent. However, limited data exist on postprandial triglycerides and glycemic control following co‐administration of high‐fat meals with a single dose of niacin in subjects with metabolic syndrome (MetS). The aim of the study was to explore whether a fat challenge containing predominantly saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs) or MUFAs plus omega‐3 long‐chain polyunsaturated (LCPUFAs) fatty acids together with a single dose of immediate‐release niacin have a relevant role in postprandial insulin and lipid status in subjects with MetS. RESULTS In a randomized crossover within‐subject design, 16 men with MetS were given a single dose of immediate‐release niacin (2 g) and ∼15 cal kg−1 body weight meals containing either SFAs, MUFAs, MUFAs plus omega‐3 LCPUFAs or no fat. At baseline and hourly over 6 h, plasma glucose, insulin, C‐peptide, triglycerides, free fatty acids (FFAs), total cholesterol, and both high‐ and low‐density lipoprotein cholesterol were assessed. Co‐administered with niacin, high‐fat meals significantly increased the postprandial concentrations of glucose, insulin, C‐peptide, triglycerides, FFAs and postprandial indices of β‐cell function. However, postprandial indices of insulin sensitivity were significantly decreased. These effects were significantly attenuated with MUFAs or MUFAs plus omega‐3 LCPUFAs when compared with SFAs. CONCLUSION In the setting of niacin co‐administration and compared to dietary SFAs, MUFAs limit the postprandial insulin, triglyceride and FFA excursions, and improve postprandial glucose homeostasis in MetS.