Combined effects of glucose and fructose on fluid absorption from hypertonic carbohydrate-electrolyte beverages.

Published: J Exerc Physiol Online 2008; 11(2), 46-55

Abstract
This study examined the effect of glucose and fructose, compared to glucose alone on water absorption from hypertonic carbohydrate-electrolyte solutions (CES) in the small intestine. Six solutions were perfused into the duodenojejunum and water flux was determined using the segmental perfusion technique. The solutions were: 1) 6% glucose, 2) 3% glucose + 3% fructose, 3) 8% glucose, 4) 4% glucose + 4% fructose, 5) 10% glucose, or 6) 5% glucose + 5% fructose. All solutions also contained 20 mEq sodium, 3 mEg potassium and flavoring/coloring to simulate commonly ingested CES. Water flux was related to osmolality (r = 0.79) and the 6% glucose, 3% glucose + 3% fructose, and 4% glucose + 4% fructose solutions promoted greater (P < 0.05) water absorption rate than the 8% glucose, 10% glucose and 5% glucose + 5% fructose solutions. These results indicate increasing osmolality negatively affects fluid absorption, and this is attenuated in a moderately hypertonic 8% CES by using both fructose and glucose compared to glucose alone.