Novel Allulose- and Amino Acid-Containing Sugar-Free Electrolyte Beverage Improves Body Water Restoration in Ad Libitum Rehydration Following Exercise-Induced Dehydration

Objectives: This study evaluated the rehydration efficacy of a novel sugar-free oral rehydration solution sweetened with allulose and amino acids (SF-ORS), compared to a traditional sugar-sweetened ORS (SS-ORS) and water. Methods: Twenty recreationally active adults (nine females) participated in a randomized crossover study involving three rehydration trials after a ~1.8% body mass loss induced by exercise in heat. Participants consumed ad libitum for 4 h one of: (a) SS-ORS (glucose/sucrose: 26 g/L, Na+: 49 mmol/L, K+: 19 mmol/L, osmolality: 223 mmol/kg); (b) SF-ORS (allulose: ~8 g/L, L-glutamine and L-alanine: ~8 g/L, Na+: 46 mmol/L, K+: 19 mmol/L, osmolality: 234 mmol/kg); or (c) plain water, all labeled with D2O (10 g/L) to trace the appearance of ingested fluid in plasma. Results: There was no statistically significant difference in total fluid intake between trials (water: 1603 ± 567, SF-ORS: 1826 ± 728, SS-ORS: 1918 ± 713 mL; p = 0.087). At 4 h, fluid retention following SF-ORS (46.6 ± 23.1%) and SS-ORS (39.7 ± 24.0%) was higher than water (24.8 ± 29.3%, all p < 0.05), and body weight was better restored following SF-ORS (0.83 ± 0.65%) than water (0.16 ± 0.77%, p = 0.011). Urine output at 3 h was lower following SF-ORS (753 ± 394 mL) than SS-ORS (976 ± 583 mL, p = 0.035). No significant difference in plasma D2O enrichment per gram of D2O ingested (average over 4 h) was found between SF-ORS (21.0 ± 5.5 ppm/g) and water (22.0 ± 5.0 ppm/g, p = 0.30), while SS-ORS (20.2 ± 4.9 ppm/g) showed lower enrichment per g ingested compared to water (p = 0.022). SF-ORS resulted in lower free water clearance than water over the rehydration period (p < 0.001). Conclusions: An allulose-sweetened, amino acid-based electrolyte beverage may be a viable option for post-exercise rehydration when limiting sugar and energy intake is desired.