Gamma-polyglutamic acid-rich natto suppresses postprandial blood glucose response in the early phase after meals: A randomized crossover study

Abstract

We evaluated the suppressive e_ects of high-gamma-polyglutamic acid (-PGA) natto on postprandial blood glucose level and insulin response. After confirming the eligibility of candidates using a pre-selective test with packaged white rice, a meal loading test including low- or high—PGA natto (with 57.6 mg (LPGA) and 439.6 mg (HPGA) of -PGA, respectively) was conducted in menaged 20 to 70 years (n = 29) and postmenopausal women aged _70 years (n = 7). On each examination day, blood samples were obtained after they fasted overnight and for 120 min after test meal loading. The primary outcome of this study was the di_erence between the measurements of the incremental area under the curve (IAUC) for blood glucose 0 to 30 min after loading of LPGA and HPGA meals. The IAUCs for blood glucose and insulin after the HPGA meal were lower than those after the LPGA meal within 45 min (0 to 15 and 0 to 30 min: p < 0.001, 0 to 45 min: p < 0.01) and 1 h (all p < 0.001) of loading, respectively. The suppressive e_ects of HPGA natto on postprandial glucose response in the early phase, which possibly relates to the risk of dysglycemia and cardiovascular disease, were clarified.