Wapnir, Raul A., Maria C. Sia, and Stanley E. Fisher. Enhancement of intestinal water absorption and sodium transport by glycerol in rats. J. Appl. Physiol. 81(6): 2523-2527, 1996.Glycerol (Gly) is a hydrophilic, absorbable, and energy-rich solute that could make water absorption more efficient. We investigated the use of Gly in a high-energy beverage containing corn syrup (CS) by using a small intestine perfusion procedure in the rat, an approach shown earlier to provide good preclinical information. The effectiveness of several formulations with Gly and CS was compared with commercial products and to experimental formulas where Gly substituted for glucose (Glc). The CS-Gly combination was more effective than preparations on the market containing sucrose and Glc-fructose syrups (G-P and G-L, respectively) in maintaining a net water absorption balance in the test jejunal segment [CS-Gly = 0.021 ± 0.226, G-L = 1.516 ± 0.467, and G-P = 0.299 ± 0.106 (SE) µl ^· min^{1 ·} cm¹ (P = 0.0113)] and in reducing sodium release into the lumen [CS-Gly = 133.2 ± 16.2, G-L = 226.7 ± 25.2, and G-P = 245.6 ± 23.4 nmol ^· min^{1 ·} cm¹ (P = 0.0022)]. In other preparations, at equal CS concentrations (60 and 80 g/l, respectively), Gly clearly improved net water absorption over a comparable Glc-containing product [CS60-Gly = 0.422 ± 0.136 and CS80-Gly = 0.666 ± 0.378 vs. CS60-Glc = 0.282 ± 0.200 and CS80-Glc = 1.046 ± 0.480 µl ^· min^{1 ·} cm¹ (P = 0.0019)]. On the basis of the data of this rat intestine perfusion model, Gly could be a useful ingredient in energy-rich beverages and might enhance fluid absorption in humans.