Whole grain vs refined wheat foods do not differ in glycaemic response, gastric emptying

Whole grain wheat foods boast of several health benefits but, in their natural composition, do not provide lower postprandial glycaemia or gastric emptying relative to their refined wheat counterparts, reveals a recent study.

A team of investigators sought to examine the effect of whole grain wheat compared with refined wheat milled products on postprandial glycaemia, gastric emptying, and subjective appetite in this randomized, crossover trial.

Sixteen healthy participants consumed six different medium-viscosity porridges made from whole grain wheat or refined wheat milled products, all from the same grain source and mill: whole wheat flour, refined wheat flour, cracked wheat, semolina, reconstituted wheat flour with fine bran, and reconstituted wheat flour with coarse bran.

The investigators measured postprandial glycaemia, gastric emptying, and appetitive response using continuous glucose monitors, the ¹³C-octanoic acid (8:0) breath test, and visual analogue scale (VAS) ratings. They also implemented Bayes factors to draw inferences on null effects.

There were little to no differences seen in glycaemia responses, with lower incremental area under the curve between 0- and 120-min glycaemia responses only for semolina (mean difference [MD], ‒966 mg min/dL, 95 percent confidence interval [CI], ‒1,775 to ‒156; p=0.02) and cracked wheat (MD, ‒721 mg min/dL, 95 percent CI, ‒1,426 to ‒16; p=0.04) compared with whole wheat flour porridge.

In addition, Bayes factors indicated weak to strong evidence for a null effect (ie, no effect of treatment type) in glycaemic response, gastric emptying, and VAS ratings.