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 with consuming a sucrose-sweetened sport drink during a 4-h WrHS simulation. In this block randomized, double-blind crossover study, 12 healthy adults (26 ± 7 yr; 6 women) completed two trials involving ingesting six 500 mL doses of a higher-fructose sport drink (55% fructose and 45% glucose; Fructose55) or a sucrose-sweetened sport drink (50% fructose and 50% glucose; Sucrose) before, during, and following a 4-h WrHS simulation that comprised three circuits of treadmill walking (10 min) and rowing (5 min) at five metabolic equivalents and 15 min 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 postexposure, at recovery, and 24 h 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)2/1,000, Sucrose: 1.6 ± 1.8 (ng/mL)2/1,000, P = 0.677). Consuming a higher-fructose-containing sport drink does not exacerbate AKI risk during WrHS when compared with a sucrose-sweetened equivalent.NEW & NOTEWORTHY This study tested whether drinking a sport drink with a higher proportion of fructose influences acute kidney injury (AKI) risk during simulated work-related heat stress. In a block randomized, double-blind crossover design, healthy adults consumed either a higher-fructose or sucrose-sweetened sport drink matched for calories, electrolytes, and carbohydrates. Despite increases in AKI biomarkers with heat stress, the type of sugar in the sport drink did not alter AKI risk, indicating that modest differences in fructose content do not meaningfully impact kidney stress.