Co-ingestion of traditional Japanese barley mixed rice (Mugi gohan) with yam paste in healthy Japanese adults decreases postprandial glucose and insulin secretion in a randomized crossover trial.

Background and objectives: Barley mixed rice, "Mugi gohan," is traditionally eaten with yam paste in Japan. Both ingredients contain dietary fiber and reportedly reduce postprandial hyperglycemia. However, evidence supporting the benefits of combining barley mixed rice with yam paste is limited. In this study, we evaluated whether ingesting a combination of barley mixed rice and yam paste affected postprandial blood glucose concentration and insulin secretion.

Methods and study design: This study followed an open-label, randomized controlled crossover design, following the unified protocol of the Japanese Association for the Study of Glycemic Index. Fourteen healthy subjects each consumed four different test meals: white rice only, white rice with yam paste, barley mixed rice, and barley mixed rice with yam paste. We measured their postprandial blood glucose and insulin concentrations after every meal, and we calculated the area under curve for glucose and insulin.

Results: Participants had significantly reduced area under curve for glucose and insulin after eating barley mixed rice with yam paste compared to when they ate white rice only. Participants had similar area under curve for glucose and insulin after eating barley mixed rice only, or eating white rice with yam paste. Participants had lower blood glucose concentrations 15 min after eating barley mixed rice only, whilst eating white rice with yam paste did not maintain lower blood glucose after 15 min.

Conclusions: Eating barley mixed rice with yam paste decreases postprandial blood glucose concentrations and reduces insulin secretion.