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Appl Physiol Nutr Metab. 2017 Dec;42(12):1283-1292. doi: 10.1139/apnm-2017-0361. Epub 2017 Aug 4.

Carbohydrate and protein intake during exertional heat stress ameliorates intestinal epithelial injury and small intestine permeability.

Author information

1
a Monash University, Department of Nutrition, Dietetics and Food, Level 1, 264 Ferntree Gully Road, Notting Hill, Victoria 3168, Australia.
2
b University of Tasmania, Sport Performance Optimisation Research Team, School of Health Sciences, Locked Bag 1322, Launceston, Tasmania 7250, Australia.
3
c Monash University, Department of Gastroenterology - The Alfred Hospital, 55 Commercial Road, Melbourne, 3004 Victoria, Australia.

Abstract

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. Eleven (male, n = 6; female, n = 5) endurance runners completed 2 h of running at 60% maximal oxygen uptake in 35 °C ambient temperature on 3 occasions in randomised order, consuming water (WATER), 15 g glucose (GLUC), or energy-matched whey protein hydrolysate (WPH) before and every 20 min during EHS. Rectal temperature and gastrointestinal symptoms were recorded every 10 min 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 ratio was used to measure small intestine permeability. Compared with WATER, GLUC, and WPH ameliorated EHS associated intestinal epithelial injury (I-FABP: 897 ± 478 pg·mL-1 vs. 123 ± 197 pg·mL-1 and 82 ± 156 pg·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 (10.2 pg·mL-1, p = 0.001). Post-EHS anti-endotoxin antibodies were higher (p < 0.01) and cortisol and interleukin-6 lower (p < 0.05) on GLUC than WATER only. Total and upper gastrointestinal symptoms were greater on WPH, compared with GLUC and WATER (p < 0.05), in response to EHS. In 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 that carbohydrate is a more appropriate option.

KEYWORDS:

I-FABP; course; exposition à la chaleur; gastrointestinal symptoms; glucose; heat exposure; hydrolysat de petit-lait; running; symptômes gastro-intestinaux; whey protein hydrolysate

PMID:
28777927
DOI:
10.1139/apnm-2017-0361
[Indexed for MEDLINE]

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