Intestinal water and electrolyte flux of glucose-polymer electrolyte solutions

Carbohydrate-containing beverages, designed for consumption during physical activity, have been shown to improve endurance and performance during prolonged exercise. However, any solution consumed during exercise should allow rapid water absorption to ensure proper hydration. In this study, nine healthy volunteers were used to assess intestinal water and electrolyte flux characteristics of two carbohydrate-electrolyte solutions compared with water. One solution (GPF) contained 5.0% glucose polymers and 2.0% fructose, while the other (GPFS) contained 3.6% glucose polymers, 1.8% fructose, and 1.6% sucrose. Both solutions contained similar amounts of sodium, chloride, potassium, magnesium, and calcium (10, 10, 5, 1.2, and 3.2 mEq X l-1, respectively). Solutions were administered via a triple-lumen perfusion tube placed just distal to the ligament of Treitz in the small intestine. Polyethylene glycol (5 g X l-1) was employed as a non-absorbable marker to measure water and mineral fluxes. Results indicated that: jejunal intestinal net water absorption was similar for the GPF carbohydrate-mineral solution when compared with perfusion of plain water and replacement of a portion of the glucose-polymer with sucrose significantly slowed net water absorption when compared with perfusion of plain water. Net sodium, chloride, and potassium absorption also were not different for either of the two perfusates. These findings suggest that the water and mineral fluxes association with these solutions are not different from water alone. Therefore, the gastric emptying rate remains as the primary limiting factor in delivering water, carbohydrate, and minerals to the body.