title: Body Position Modulates Gastric Emptying and Affects the Post-Prandial Rise in Plasma Amino Acid Concentrations Following Protein Ingestion in Humans.
abstract: Dietary protein digestion and amino acid absorption kinetics determine the post-prandial muscle protein synthetic response. Body position may affect gastrointestinal function and modulate the post-prandial rise in plasma amino acid availability. We aimed to assess the impact of body position on gastric emptying rate and the post-prandial rise in plasma amino acid concentrations following ingestion of a single, meal-like amount of protein. In a randomized, cross-over design, eight healthy males (25 ± 2 years, 23.9 ± 0.8 kg·m(-2)) ingested 22 g protein and 1.5 g paracetamol (acetaminophen) in an upright seated position (control) and in a -20° head-down tilted position (inversion). Blood samples were collected during a 240-min post-prandial period and analyzed for paracetamol and plasma amino acid concentrations to assess gastric emptying rate and post-prandial amino acid availability, respectively. Peak plasma leucine concentrations were lower in the inversion compared with the control treatment (177 ± 15 vs. 236 ± 15 mmol·L(-1), p < 0.05), which was accompanied by a lower plasma essential amino acid (EAA) response over 240 min (31,956 ± 6441 vs. 50,351 ± 4015 AU; p < 0.05). Peak plasma paracetamol concentrations were lower in the inversion vs. control treatment (5.8 ± 1.1 vs. 10.0 ± 0.6 mg·L(-1), p < 0.05). Gastric emptying rate and post-prandial plasma amino acid availability are significantly decreased after protein ingestion in a head-down tilted position. Therefore, upright body positioning should be considered when aiming to augment post-prandial muscle protein accretion in both health and disease.
authors.affiliation: Department of Human Movement Sciences, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, P.O. Box 616, Maastricht 6200 MD, The Netherlands. andy.holwerda@maastrichtuniversity.nl.
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Holwerda
authors.affiliation: Department of Surgery, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, P.O. Box 616, Maastricht 6200 MD, The Netherlands. kaatje.lenaerts@maastrichtuniversity.nl.
authors.forename: Kaatje
authors.initials: K
authors.lastname: Lenaerts
authors.affiliation: Department of Clinical Genetics, Maastricht University Medical Centre+, P.O. Box 616, Maastricht 6200 MD, The Netherlands. jorgen.bierau@mumc.nl.
authors.forename: Jörgen
authors.initials: J
authors.lastname: Bierau
authors.affiliation: Department of Human Movement Sciences, NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, P.O. Box 616, Maastricht 6200 MD, The Netherlands. l.vanloon@maastrichtuniversity.nl.
authors.forename: Luc J C
authors.initials: LJ
authors.lastname: van Loon
mesh_terms: D000082:Acetaminophen / Q000008:administration & dosage / Q000493:pharmacokinetics; D000328:Adult; D000596:Amino Acids / Q000097:blood* / Q000378:metabolism; D018712:Analgesics, Non-Narcotic / Q000008:administration & dosage / Q000493:pharmacokinetics; D001786:Blood Glucose; D018592:Cross-Over Studies; D004044:Dietary Proteins; D005746:Gastric Emptying / Q000502:physiology*; D006801:Humans; D007328:Insulin / Q000097:blood; D008297:Male; D009747:Nutritional Physiological Phenomena; D019518:Postprandial Period / Q000502:physiology*; D011187:Posture
chemical_list: D000596:Amino Acids; D018712:Analgesics, Non-Narcotic; D001786:Blood Glucose; D004044:Dietary Proteins; D007328:Insulin; D000082:Acetaminophen
keywords: body position; digestion; gastric emptying; protein