a Monash University, Department of Nutrition, Dietetics and Food, Level 1, 264 Ferntree Gully Road, Notting Hill, Victoria 3168, Australia.
b University of Tasmania, Sport Performance Optimisation Research Team, School of Health Sciences, Locked Bag 1322, Launceston, Tasmania 7250, Australia.
Appl Physiol Nutr Metab. 2017 Dec;42(12):1283-1292. doi: 10.1139/apnm-2017-0361. Epub 2017 Aug 4.
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 vs. 123 ± 197 pg·mL and 82 ± 156 pg·mL, 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, 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.
运动性热应激（EHS）会破坏胃肠道的完整性，导致内毒素血症和细胞因子血症，从而产生症状和健康影响。本研究旨在确定 EHS 期间碳水化合物和蛋白质摄入对胃肠道完整性、症状和全身反应的影响。11 名（男性 6 名；女性 5 名）耐力跑者在 3 次随机顺序的实验中，在 35°C 环境温度下以 60%最大摄氧量的速度跑步 2 小时，在 EHS 前和每 20 分钟摄入水（WATER）、15 克葡萄糖（GLUC）或能量匹配的乳清蛋白水解物（WPH）。在 EHS 期间，每 10 分钟记录一次直肠温度和胃肠道症状。在 EHS 前后和恢复期间采集血液，以确定血浆中肠道脂肪酸结合蛋白（I-FABP）的浓度作为肠道上皮损伤的标志物、皮质醇、内毒素和炎症细胞因子。尿乳果糖/鼠李糖比值用于测量小肠通透性。与 WATER 相比，GLUC 和 WPH 改善了 EHS 相关的肠道上皮损伤（I-FABP：897 ± 478 pg·mL 与 123 ± 197 pg·mL 和 82 ± 156 pg·mL，分别为 p < 0.001）和小肠通透性（乳果糖/鼠李糖比值：0.034 ± 0.014 与 0.017 ± 0.005 和 0.008 ± 0.002，分别为 p = 0.001）。所有试验均在 EHS 后观察到内毒素血症（10.2 pg·mL，p = 0.001）。与 WATER 相比，GLUC 仅在 EHS 后，抗内毒素抗体更高（p < 0.01），皮质醇和白细胞介素-6 更低（p < 0.05）。与 GLUC 和 WATER 相比，WPH 在 EHS 期间会引起更大的总胃肠道和上胃肠道症状（p < 0.05）。总之，EHS 期间碳水化合物和蛋白质的摄入可改善肠道损伤和通透性。碳水化合物还支持内毒素清除并降低应激标志物，而蛋白质似乎会增加胃肠道症状，这表明碳水化合物是更好的选择。
