Evaluating Crossbred Red Rice Variants for Postprandial Glucometabolic Responses: A Comparison with Commercial Varieties

Abstract

Consumption of white rice predisposes some Asian populations to increased risk of type 2 diabetes. We compared the postprandial glucometabolic responses to three newly-developed crossbred red rice variants (UKMRC9, UKMRC10, UKMRC11) against three selected commercial rice types (Thai red, Basmati white, Jasmine white) using 50-g carbohydrate equivalents provided to 12 normoglycaemic adults in a crossover design. Venous blood was drawn fasted and postprandially for three hours. Glycaemic (GI) and insulin (II) indices, incremental areas-under-the-curves for glucose and insulin (IAUCins), indices of insulin sensitivity and secretion, lactate and peptide hormones (motilin, neuropeptide-Y, orexin-A) were analyzed. The lowest to highest trends for GI and II were similar i.e., UKMRC9 < Basmati < Thai red < UKMRC10 < UKMRC11 < Jasmine. Postprandial insulinaemia and IAUCins of only UKMRC9 were significantly the lowest compared to Jasmine. Crude protein and fiber content correlated negatively with the GI values of the test rice. Although peptide hormones were not associated with GI and II characteristics of test rice, early and late phases of prandial neuropeptide-Y changes were negatively correlated with postprandial insulinaemia. This study indicated that only UKMRC9 among the new rice crossbreeds could serve as an alternative cereal option to improve diet quality of Asians with its lowest glycaemic and insulinaemic burden.

Keywords: cross-breeding; glycaemic index; insulin resistance; peptide hormones; red rice.

Figure 1

Baseline-adjusted trends (mean ± SEM) in postprandial plasma (a) glucose; (b) insulin and (c) lactate responses for six test rice and glucose standard, and incremental area-under-the-curve (IAUC) for postprandial (ai) glycaemia; (bi) insulinaemia and (ci) lactataemia. ^§ Mean values bearing the same alphabets were not significantly different (p > 0.05, univariate analysis of variance followed by Tukey’s post hoc test, ns = not significant); η_p² = partial eta-squared, 0.01, 0.06 and 0.14 were used to denote small, moderate and large differences in measured outcomes, respectively.

Figure 2

Baseline-adjusted trends in postprandial plasma (a) motilin (MTL); (b) neuropeptide-Y (NPY) and (c) orexin-A (ORXA) responses for six test rice and glucose standard. Note: Horizontal bars = smallest and largest values; Lower band = 25th percentile; Upper band = 75th percentile; (×) = median; (•) = outlier and (◊) = extreme values defined as 1.5 × (Q3 − Q1) below 25th or above 75th percentiles.