Faster gastric emptying for glucose-polymer and fructose solutions than for glucose in humans

Summary This study examined the rates of gastric emptying for water and 13 different carbohydrate-containing solutions in seven subjects, using conventional gastric intubation techniques. The rates of gastric emptying for water and a 10% glucose-polymer solution were also measured during 90 min of treadmill running at 75% of each subject's maximum oxygen consumption \((\dot V_{O_{2 max} } )\). At rest, 15% glucose-polymer (P) and fructose (F) solutions emptied more rapidly from the stomach and provided a faster rate of carbohydrate delivery than did a 15% glucose (G) solution (p<0.05). The G solutions showed a constant energy delivery rate of 3.3 kcal · min⁻¹; energy delivery from P and F solutions rose with increasing solution concentrations. The osmolality of the gastric aspirate predicted the rate of gastric emptying for all solutions (p<0.05) but overestimated rates of emptying for 10% and 15% P solutions and underestimated emptying rates for 10% and 15% F solutions. Exercise at 75% \(\dot V_{O_{2 max} }\) decreased the rate of gastric emptying of water but not of 10% P solutions. Thus the different rates of gastric emptying for different carbohydrate-containing solutions were not entirely explained by differences in osmolality. Furthermore, exercise may have different effects on the gastric emptying rates of water and carbohydrate solutions.