Consumption of whole-grain rice lowers postprandial blood glucose response
Whole-grain rice significantly reduces postprandial blood glucose response relative to white rice, results of a systematic review and meta-analysis have shown.
“In most of the studies on wheat and rye, the postprandial blood glucose responses to foods formulated with wholemeal compared with refined flours were compared,” the authors said. “Whether reductions in the blood glucose AUC can be achieved with whole-grain (as opposed to wholemeal) wheat and rye requires further investigation.”
A total of 20 publications were included, with 10, 14 and five strata (or active-control comparisons) on whole-grain wheat, rice and rye, respectively.
Ground (wholemeal) vs white wheat consumption did not correlate with a significant reduction in blood glucose area under the curve (AUC) (–6.7 mmol/L ⋅ min; 95 percent CI, –25.1 to 11.7 mmol/L ⋅ min; p=0.477). Consumption of wholemeal vs endosperm rye was also not associated with a significant reduction in blood glucose AUC (–5.5 mmol/L ⋅ min; –24.8 to 13.9 mmol/L ⋅ min; p=0.576).
In contrast, consumption of intact (whole-grain) vs white rice correlated with a significant reduction in blood glucose AUC (–40.5 mmol/L ⋅ min; –59.6 to –21.3 mmol/L ⋅ min; p<0.001).
The authors systematically searched 11 electronic databases to identify studies published up to and including November 2017, including randomized controlled trials comparing the effects of whole-grain wheat, rice or rye with those of each grain’s refined counterpart on postprandial blood glucose AUC. The difference in blood glucose AUC after the consumption of whole vs refined grain was used to compute pooled effect sizes.
“Whole grains are often referred to collectively, despite differences in their composition, physical structure, processing and potential health benefits,” the authors said.