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Gastrointestinal Tolerance of Low, Medium and High Dose Acute Oral l -Glutamine Supplementation in Healthy Adults: A Pilot Study

Authors
  • Ogden, Henry B.1
  • Child, Robert B.
  • Fallowfield, Joanne L.2
  • Delves, Simon K.2
  • Westwood, Caroline S.1
  • Millyard, Alison1
  • Layden, Joseph D.1
  • 1 (J.D.L.)
  • 2 (S.K.D.)
Type
Published Article
Journal
Nutrients
Publisher
MDPI AG
Publication Date
Sep 27, 2020
Volume
12
Issue
10
Identifiers
DOI: 10.3390/nu12102953
PMID: 32992440
PMCID: PMC7601811
Source
PubMed Central
Keywords
License
Green

Abstract

l -Glutamine (GLN) is a conditionally essential amino acid which supports gastrointestinal (GI) and immune function prior to catabolic stress (e.g., strenuous exercise). Despite potential dose-dependent benefits, GI tolerance of acute high dose oral GLN supplementation is poorly characterised. Fourteen healthy males (25 ± 5 years; 1.79 ± 0.07 cm; 77.7 ± 9.8 kg; 14.8 ± 4.6% body fat) ingested 0.3 (LOW), 0.6 (MED) or 0.9 (HIGH) g·kg·FFM−1 GLN beverages, in a randomised, double-blind, counter-balanced, cross-over trial. Individual and accumulated GI symptoms were recorded using a visual analogue scale at regular intervals up to 24-h post ingestion. GLN beverages were characterised by tonicity measurement and microscopic observations. 24-h accumulated upper- and lower- and total-GI symptoms were all greater in the HIGH, compared to LOW and MED trials ( p < 0.05). Specific GI symptoms (discomfort, nausea, belching, upper GI pain) were all more pronounced on the HIGH versus LOW GLN trial ( p < 0.05). Nevertheless, most symptoms were still rated as mild. In comparison, the remaining GI symptoms were either comparable (flatulence, urge to regurgitate, bloating, lower GI pain) or absent (heart burn, vomiting, urge to defecate, abnormal stools, stitch, dizziness) between trials ( p > 0.05). All beverages were isotonic and contained a dose-dependent number of GLN crystals. Acute oral GLN ingestion in dosages up to 0.9 g·kg·FFM−1 are generally well-tolerated. However, the severity of mild GI symptoms appeared dose-dependent during the first two hours post prandial and may be due to high-concentrations of GLN crystals.

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