The acute effect of a β-glucan-enriched oat bread on gastric emptying, GLP-1 response, and postprandial glycaemia and insulinemia: a randomised crossover trial in healthy adults

Sammendrag

Background The cereal fbre β-glucan reduces postprandial glycaemia, however, the underlying mechanisms are not fully understood. Thus, the aim of this study was to investigate the acute efect of a β-glucan-enriched oat bread on gastric emptying half-time (T1/2), gastric emptying lag phase (Tlag), and gastric emptying rate (GER), and the secre‑ tion of glucagon-like peptide-1 (GLP-1) as potential means to infuence postprandial glycaemia. Methods A randomised crossover trial was conducted in 22 healthy adults (age 24.6±3.1 years, BMI 23.1±2.7 kg/m2 ) receiving 25 g available carbohydrates from a β-glucan-enriched oat bread or a control whole-wheat bread at two non-consecutive days. T1/2, Tlag, and GER were determined based on ultrasound measures of the cross-sectional gas‑ tric antrum area in the fasting state and 15, 30, 45, 60, 90, and 120 min postprandially. Capillary glucose, serum insulin, and plasma GLP-1 concentrations were measured at the same time points. Results A biphasic pattern of gastric emptying with a distinct Tlag before the commencement of emptying was observed in most subjects for both bread types. While no diferences in GER were evident (p=0.562), consump‑ tion of the oat bread signifcantly increased T1/2 by 18 min and Tlag by 14 min compared with the whole-wheat bread (p=0.005 and p=0.010, respectively). In addition, the oat bread signifcantly reduced iAUC2h for glucose and insulin responses compared with the whole-wheat bread (p=0.001 and p<0.001, respectively). There were no signifcant dif‑ ferences in GLP-1 response between the two breads (p=0.892). Conclusion The increased T1/2 and Tlag could ofer a potential mechanism for the observed attenuation of postpran‑ dial glycaemia and insulinemia after consumption of the β-glucan-enriched oat bread compared with the wholewheat bread. Trial registration: The study is registered at clinicaltrails.gov (NCT04571866). Keywords Oats, β-glucans, Gastric emptying, Ultrasound, Postprandial responses, Glycaemia, Insulinemia, Gastrointestinal hormones