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

<jats:title>Abstract</jats:title><jats:sec> <jats:title>Background</jats:title> <jats:p>The cereal fibre β-glucan reduces postprandial glycaemia, however, the underlying mechanisms are not fully understood. Thus, the aim of this study was to investigate the acute effect of a β-glucan-enriched oat bread on gastric emptying half-time (<jats:italic>T</jats:italic><jats:sub><jats:italic>1/2</jats:italic></jats:sub>), gastric emptying lag phase (<jats:italic>T</jats:italic><jats:sub><jats:italic>lag</jats:italic></jats:sub>), and gastric emptying rate (GER), and the secretion of glucagon-like peptide-1 (GLP-1) as potential means to influence postprandial glycaemia.</jats:p> </jats:sec><jats:sec> <jats:title>Methods</jats:title> <jats:p>A randomised crossover trial was conducted in 22 healthy adults (age 24.6 ± 3.1 years, BMI 23.1 ± 2.7 kg/m<jats:sup>2</jats:sup>) receiving 25 g available carbohydrates from a β-glucan-enriched oat bread or a control whole-wheat bread at two non-consecutive days. <jats:italic>T</jats:italic><jats:sub><jats:italic>1/2</jats:italic></jats:sub>, <jats:italic>T</jats:italic><jats:sub><jats:italic>lag</jats:italic></jats:sub>, and GER were determined based on ultrasound measures of the cross-sectional gastric 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.</jats:p> </jats:sec><jats:sec> <jats:title>Results</jats:title> <jats:p>A biphasic pattern of gastric emptying with a distinct <jats:italic>T</jats:italic><jats:sub><jats:italic>lag</jats:italic></jats:sub> before the commencement of emptying was observed in most subjects for both bread types. While no differences in GER were evident (<jats:italic>p</jats:italic> = 0.562), consumption of the oat bread significantly increased <jats:italic>T</jats:italic><jats:sub><jats:italic>1/2</jats:italic></jats:sub> by 18 min and <jats:italic>T</jats:italic><jats:sub><jats:italic>lag</jats:italic></jats:sub> by 14 min compared with the whole-wheat bread (<jats:italic>p</jats:italic> = 0.005 and <jats:italic>p</jats:italic> = 0.010, respectively). In addition, the oat bread significantly reduced iAUC<jats:sub>2h</jats:sub> for glucose and insulin responses compared with the whole-wheat bread (<jats:italic>p</jats:italic> = 0.001 and <jats:italic>p</jats:italic> &lt; 0.001, respectively). There were no significant differences in GLP-1 response between the two breads (<jats:italic>p</jats:italic> = 0.892).</jats:p> </jats:sec><jats:sec> <jats:title>Conclusion</jats:title> <jats:p>The increased <jats:italic>T</jats:italic><jats:sub><jats:italic>1/2</jats:italic></jats:sub> and <jats:italic>T</jats:italic><jats:sub><jats:italic>lag</jats:italic></jats:sub> could offer a potential mechanism for the observed attenuation of postprandial glycaemia and insulinemia after consumption of the β-glucan-enriched oat bread compared with the whole-wheat bread.</jats:p> <jats:p><jats:italic>Trial registration</jats:italic>: The study is registered at clinicaltrails.gov (NCT04571866).</jats:p> </jats:sec>