Food ingestion in an upright sitting position increases post-prandial amino acid availability when compared to food ingestion in a lying down position

Dietary protein digestion and absorption kinetics determine the post-prandial increase in muscle protein synthesis. We recently demonstrated that body position during feeding can modulate the post-prandial rise in plasma amino acid availability. Here we investigated whether protein ingestion in an upright sitting body position accelerates gastric emptying and improves dietary protein digestion and subsequent amino acid absorption compared with feeding in a supine lying body position. In a crossover design, eight young males (26±1 y, 24.0±0.9 kg.m-2) ingested 20 g intrinsically L-[1-13C]-phenylalanine labeled milk protein plus 1.5 g paracetamol while sitting in an upright position or lying down in a supine position. Blood samples were collected frequently during a 5 h post-prandial period. Gastric emptying rates and dietary protein digestion and absorption were assessed using plasma paracetamol and amino acid concentrations as well as plasma L-[1-13C]-phenylalanine enrichments. Peak plasma leucine concentrations were higher when protein was ingested in an upright sitting vs lying position (213±15 vs 193±12 mol.L-1, PThe accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author