Hydrating with a higher-fructose sport drink does not worsen acute kidney injury risk during simulated work-related heat stress

Fructose containing soft drinks worsen acute kidney injury (AKI) risk during simulated work related heat stress (WrHS), but the fructose content is comparatively lower in sport drinks. This study tested the hypothesis that consuming a higher-fructose sport drink exacerbates AKI risk compared to consuming a sucrose-sweetened sport drink during a four-hour WrHS simulation. In this block randomized, double-blind crossover study, 12 healthy adults (26±7 y; 6 women) completed two trials involving ingesting six 500 mL doses of a higher-fructose sport drink (55% fructose & 45% glucose; Fructose55) or a sucrose-sweetened sport drink (50% fructose & 50% glucose; Sucrose) before, during, and following a 4 hour WrHS simulation that comprised three circuits of treadmill walking (10 minutes) and rowing (5 minutes) at five metabolic equivalents and 15 minutes of rest every hour. Drinks were matched for total carbohydrates, calories, and electrolytes and modestly matched for osmolality. Urine and blood samples were collected pre- and post-exposure, at recovery, and 24 hours post-visit. AKI risk was quantified as the product of urine insulin-like growth factor-binding protein 7 and urine tissue inhibitor of metalloproteinase-2 ([IGFBP7•TIMP-2]) normalized to specific gravity. Peak rectal temperature (Fructose55: 38.3±0.7°C, Sucrose: 38.3±0.7°C, p=0.991) and percent change in body weight (Fructose55: -0.7±1.0%, Sucrose: -0.9±1.0%, p=0.466) were not different between trials. Urinary [IGFBP7•TIMP-2] increased over time (p<0.001) but did not differ between trials (peak change - Fructose55: 1.7±1.6 (ng/mL)2/1000, Sucrose: 1.6±1.8 (ng/mL)2/1000, p=0.677). Consuming a higher-fructose containing sport drink does not exacerbate AKI risk during WrHS when compared to a sucrose-sweetened equivalent.