Effect of Different Osmolalities, CHO Types, and [CHO] on Gastric Emptying in Humans

This study investigated the effect of beverage osmolalities, carbohydrate (CHO) type, and CHO concentration on gastric emptying in euhydrated subjects at rest.

The gastric emptying of water (W), four glucose beverages (2%, 4%, 6%, and 8% glucose: 2G, 4G, 6G, and 8G), and four sucrose beverages (2%, 4%, 6%, and 8% sucrose: 2S, 4S, 6S, and 8S) were determined in eight healthy subjects using the modified George double-sampling technique. Subjects ingested a beverage (7 mL·kg body weight) containing 25 ppm phenol red as quickly as possible (≤1.0 min), and subsequent gastric and blood samples were collected every 10 min for 40 min. A linear regression and a repeated-measures ANOVA were used for statistical analysis.

The gastric secretion volume was not significantly different among beverages across time. Gastric residual beverage volume (GRBV) at each sampling time point was not different among 2S, 4S, 6S, 8S, and water (P > 0.05). The 8G resulted in a significantly greater GRBV compared with other beverages at 20, 30, and 40 min (P < 0.05). GRBV from 6G was significantly higher than 2G at 30 min, but no other statistical differences were found among W, 2G, 4G, and 6G. The 8S had a greater GRBV compared with W at 40 min (P < 0.05). Mean gastric osmolality positively correlated to mean GRBV (r = 0.93). Gastric emptying rate was negatively correlated to the calories emptied (r = 0.84) with a greater effect from glucose beverages compared with sucrose beverages.

These data suggest that glucose exerts a stronger inhibitory stimulus compared with sucrose on gastric emptying and that a physiological threshold exists for the combined influence of glucose concentration and beverage osmolality to trigger the feedback inhibition of gastric emptying.