Riceberry rice (Oryza sativa L.) slows gastric emptying and improves the postprandial glycaemic response.

Postprandial glycemia is a key determinant of overall glycemic control. One mechanism by which dietary strategies can reduce postprandial glycemic excursions is by slowing gastric emptying. This study aimed to evaluate the acute effect of ingesting riceberry rice (RR) compared to that of ingesting white rice (WR) on gastric emptying rate (GER), plasma glucose, and glucose-regulating hormones, including insulin, glucose-dependent insulinotropic polypeptide (GIP), and glucagon-like peptide 1 (GLP-1), in healthy subjects. A randomized, open-label, within-subject, crossover study was performed in 6 healthy men. GER was measured by scintigraphy over 240 minutes, and plasma concentrations of glucose, insulin, GLP-1 and GIP were measured at multiple time points over 180 minutes. This study revealed that RR slows GER with a reduction in postprandial plasma glucose concentrations compared to WR. Plasma insulin and GLP-1 concentrations did not differ between RR and WR. However, plasma GIP concentrations were markedly increased after WR ingesting versus after RR ingestion. We conclude that RR attenuates postprandial glycemia by slowing GER without altering plasma insulin or GLP-1. Plasma GIP concentrations are likely related to differences in GER and carbohydrate absorption. We propose that dietary fiber-enriched foods, including RR, could contribute to improvement in postprandial glycemia via delayed gastric emptying.