Effect of wheat bread with elevated amylose on postprandial glycaemic response: a randomised crossover trial delivered remotely using continuous glucose monitoring

Abstract

This study measured the effect of white bread made with a starch branching enzyme II (sbeII) mutant wheat flour with elevated amylose on postprandial glycaemic response compared to an isoglucidic white bread made with a wild-type (WT) control flour. A randomised, double-blind, placebo-controlled two-period crossover trial was conducted to measure glycaemic responses after consuming sbeII and WT bread rolls, in duplicates. The study, comprising 26 healthy adult participants (≥18 years of age; BMI ≥ 18 and ≤30 kg m⁻²; HbA1C < 42 mmol mol⁻¹, 6.0%), was conducted remotely in the participants’ homes and interstitial glucose concentration was measured by continuous glucose monitors on the upper arm for 10 days. No harms or adverse events were detected; one participant withdrew from the study due to inability to finish the bread roll meal. The maximum rise in glucose within 2 hours did not differ significantly between breads (−0.08 ± 0.12 mMol L⁻¹, mean difference ± SE, p = 0.514), even though in vitro starch digestion was ∼7% lower for the sbeII bread than the WT (p = 0.006). Effects on satiety and palatability were evaluated using online questionnaires; there was no difference between products in their overall effects on satiety, however more participants preferred the WT bread compared to the sbeII bread, which had a slightly harder and less resilient texture when measured instrumentally. Future studies should investigate the dose-dependent effects of foods with increased amylose on glycaemic responses to determine whether higher levels of amylose could yield greater metabolic benefits, while maintaining palatability and consumer acceptance.