Consumption of a meal containing refined barley flour bread is associated with a lower postprandial blood glucose concentration after a second meal compared with one containing refined wheat flour bread in healthy Japanese: A randomized control trial

Objective: Foods reducing postprandial hyperglycemia could suppress the postprandial blood glucose response after the next meal (a "second-meal" effect). However, the second-meal effect of refined barley flour bread has not been evaluated. The aim of this study is to determine whether consumption of refined barley flour bread reduces postprandial glucose concentrations after this and the subsequent meal. Methods: We enrolled 23 healthy young Japanese adults and conducted a randomized, double-blind, placebo-controlled, crossover study. The participants consumed refined barley flour bread containing 2.5 g beta-glucan or refined wheat flour bread in a first meal, then consumed three rice balls as a second meal. Their postprandial blood glucose concentrations were measured 0, 15, 30, 45, 60, 90, and 120 min after both meals. Participants with fasting glucose concentrations above the diagnostic threshold for diabetes were excluded. Results: The blood glucose concentration 30 min after the first meal was significantly lower (P < 0.05) if refined barley flour bread (7.1 +/- 1.0 mmol/L) rather than refined wheat flour bread (7.7 +/- 1.2 mmol/L) was consumed. Significantly lower glucose concentrations after the second meal measured at 60 (P < 0.05, barley flour bread: 8.7 +/- 1.8 mmol/L, wheat flour bread: 9.3 +/- 1.7 mmol/L) and 90 min (P < 0.01, barley flour bread: 7.8 +/- 1.4 mmol/L, wheat flour bread: 8.8 +/- 2.1 mmol/L) were lower in participants who had previously consumed the refined barley flour bread. Conclusions: Consumption of bread made with refined barley flour lowers postprandial blood glucose concentration after this and a subsequent meal compared with the consumption of refined wheat flour bread in healthy young Japanese adults. (C) 2019 Elsevier Inc. All rights reserved.