University Of Tasmania
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Carbohydrate and protein intake during exertional-heat stress ameliorates intestinal epithelial injury and small intestine permeability

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journal contribution
posted on 2023-05-19, 09:36 authored by Snipe, RMJ, Khoo, A, Kiktic, CM, Gibson, P, Costa, RJS

Background: Exertional-heat stress (EHS) disturbs the integrity of the gastrointestinal tract leading to endotoxaemia and cytokinaemia, which have symptomatic and health implications. This study aimed to determine the effects of carbohydrate and protein intake during EHS on gastrointestinal integrity, symptoms and systemic responses.

Methods: Eleven (male n=6, female n=5) endurance runners completed 2h running at 60% V̇O2max in 35°C ambient temperature on three occasions in randomised order, consuming water (WATER) or 15g glucose (GLUC) or energy-matched whey protein hydrolysate (WPH) before and every 20min during EHS. Rectal temperature and gastrointestinal symptoms were recorded every 10min during EHS. Blood was collected pre- and post-EHS, and during recovery to determine plasma concentrations of intestinal fatty-acid binding protein (I-FABP) as a marker of intestinal epithelial injury, cortisol, endotoxin, and inflammatory cytokines. Urinary lactulose:L-rhamnose was used to measure small intestine permeability.

Results: Compared to WATER, GLUC and WPH ameliorated EHS-associated intestinal epithelial injury (I-FABP: 897±478pg·ml-1 vs. 123±197pg·ml-1 and 82±156pg·ml-1, respectively, p<0.001) and small intestine permeability (lactulose:L-rhamnose ratio 0.034±0.014 vs. 0.017±0.005 and 0.008±0.002, respectively, p=0.001). Endotoxaemia was observed post-EHS in all trials (10.2pg·ml-1, p=0.001). Post-EHS anti-endotoxin antibodies were higher (p<0.01) and cortisol and IL-6 lower (p<0.05) on GLUC than WATER only. Total and upper-gastrointestinal symptoms were greater on WPH, compared to GLUC and WATER (p<0.05), in response to EHS.

Conclusion: Carbohydrate and protein intake during EHS ameliorates intestinal injury and permeability. Carbohydrate also supports endotoxin clearance and reduces stress markers, while protein appears to increase gastrointestinal symptoms. Suggesting carbohydrate is a more appropriate option.


Publication title

Applied physiology, nutrition, and metabolism










School of Health Sciences


Canadian Science Publishing

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Copyright 2017 the Authors

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  • Open

Socio-economic Objectives

Specific population health (excl. Indigenous health) not elsewhere classified

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