Resistant Starch from High-Amylose Maize Increases Insulin Sensitivity in Overweight and Obese Men

This study evaluated the effects of 2 levels of intake of high-amylose maize type 2 resistant starch (HAM-RS2) on insulin sensitivity (S-I) in participants with waist circumference >= 89 (women) or >= 102 cm (men). Participants received 0 (control starch), 15, or 30 g/d (double-blind) of HAM-RS2 in random order for 4-wk periods separated by 3-wk washouts. Minimal model SI was assessed at the end of each period using the insulin-modified iv. glucose tolerance test. The efficacy evaluable sample included 11 men and 22 women (mean +/- SEM) age 49.5 +/- 1.6 y, with a BMI of 30.6 +/- 0.5 kg/m(2) and waist circumference 105.3 +/- 1.3 cm. A treatment main effect (P = 0.018) and a treatment X sex interaction (P = 0.033) were present. In men, least squares geometric mean analysis for SI did not differ after intake of 15 g/d HAM-RS2 (6.90 x 10(-5) pmol(-1). L-1 x min(-1)) and 30 g/d HAM-RS2 (7.13 x 10(-5) pmol(-1). L-1 x min(-1)), but both were higher than after the control treatment (4.66 x 10(-5) pmol(-1) . L-1 x min(-1)) (P < 0.05). In women, there was no difference among the treatments (overall least squares In-transformed mean pooled SEM = 1.80 +/- 0.08; geometric mean = 6.05 X 10(-5) pmol(-1) . L-1 min(-1)). These results suggest that consumption of 15-30 g/d of HAM-RS2 improves SI in men. Additional research is needed to understand the mechanisms that might account for the treatment x sex interaction observed. J. Nutr. 142: 717-723, 2012.