Plant-protein supplementation improves thermoregulatory responses and ameliorates markers of intestinal damage during exercise in the heat.

Exercise in the heat often causes gastrointestinal (GI) disturbances, which can impair performance. Single amino acid supplementation can attenuate gut damage and enhance exercise tolerance; however, the effectiveness of innate amino acid blends from plant-based proteins remains underexplored. In this study, we investigated the effects of a novel fava bean-derived plant protein (ATURA) on thermoregulation, endurance performance and GI disturbances during exercise. Twelve healthy, non-heat-acclimatized participants completed an exercise trial (10 min walk, 40 min run, graded exercise test) in the heat (35°C; 40% relative humidity), before and after 8 days of ATURA (60 g/day) or placebo, in a double-blind, randomized, cross-over design. Whole-body sweat rate, local sweat rate, pulmonary gas exchange, skin and core temperature and perceptual responses were monitored, with pre- and post-trial blood samples. ATURA increased whole-body sweat rate (11%; P = 0.03) and back local sweat rate (11%; P < 0.001) and reduced core temperature (ATURA, 38.7°C ± 0.5°C; placebo, 38.8°C ± 0.5°C; P = 0.04) and thermal sensation (P = 0.05) in comparison to placebo. There were no differences for skin temperature, thermal comfort or graded exercise test time (P > 0.05). ATURA reduced postexercise intestinal fatty-acid binding protein (22%) compared with placebo (P = 0.05), with no difference for soluble CD14 or GI symptoms. Pre-to-post HSP70 was higher after ATURA (12%, P = 0.05), with no difference for interleukin-6 (P > 0.05). Pre-exercise fava bean protein reduced postexercise intestinal fatty-acid binding protein, indicating a potential protective effect on intestinal integrity, and was well tolerated, without increasing GI symptoms. Exploratory outcomes suggest possible thermoregulatory benefits, warranting further investigation.