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Matched whole grain and refined wheat milled products do not differ in glycemic response or gastric emptying in a randomized, crossover trial
Elizabeth A Pletsch, Anna M R Hayes, Mohammad Chegeni, Bruce R Hamaker
The American Journal of Clinical Nutrition, nqab434, https://doi.org/10.1093/ajcn/nqab434
Published: 06 January 2022

Abstract
Background
Epidemiological and some clinical studies support the view that whole grain foods have lower glycemic response compared to refined grain foods. However, from the perspective of food material properties, it is not clear why whole grain cereals containing mostly insoluble and non-viscous dietary fibers (e.g., wheat) would reduce postprandial glycemia.
Objectives
We hypothesized that glycemic response for whole grain wheat milled products would not differ from that of refined wheat when potentially confounding variables (wheat source, food form, particle size, viscosity) are matched. Our objective was to study the effect of whole grain versus refined wheat milled products on postprandial glycemia, gastric emptying, and subjective appetite.
Design
Using a randomized crossover design, healthy participants (n = 16) consumed six different medium-viscosity porridges made from whole grain 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. Postprandial glycemia, gastric emptying, and appetitive response were measured using continuous glucose monitors, the 13C-octanoic acid breath test, and visual analog scale (VAS) ratings. Bayes factors were implemented to draw inferences about null effects.
Results
Little-to-no differences were observed in glycemic responses, with lower incremental area under the curve (iAUC0-120 min) glycemic response only for semolina (mean difference [MD]: –966 mg min/dL; 95% CI: –1775, –156; P = 0.02) and cracked wheat (MD: –721 mg min/dL; 95% CI: –1426, –16; P = 0.04) compared to whole wheat flour porridge. Bayes factors suggested weak-to-strong evidence for a null effect (i.e., no effect of treatment type) in glycemic response, gastric emptying, and VAS ratings.
Conclusions
While whole grain wheat foods provide other health benefits, they did not in their natural composition confer lower postprandial glycemia or gastric emptying compared to their refined wheat counterparts.

Conclusion

There is insufficient evidence from randomised controlled trials to date to recommend consumption of whole grain diets to reduce the risk of cardiovascular disease, or lower blood cholesterol, or blood pressure.

Kokojyvävehnästä ja puhdistetusta vehnästä tehtyjä tuotteita verrattiin tässä Oxfordissa tehdyssä RCT:ssä.

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