Objective: The effects of postprandial water intake on the gastrointestinal tract have not been systematically investigated in humans.
Material and methods: In 8 healthy volunteers, the gastric antral pressure was measured with a strain gauge transducer, while the esophageal and lower esophageal sphincter pressures were measured with an infused catheter with a Dent sleeve. The esophageal pH at 5 cm above the lower sphincter was measured with a microglass electrode. A standard test meal (560 kcal) was eaten and 500 ml water was ingested 1 h later. The plasma cholecystokinin level was assessed at 4-min intervals. As a control, the same study was done on another day with sham water intake.
Results: At 4 min after water intake, there was a significant decrease in gastric antral motility and a significant increase in the plasma cholecystokinin level. Water intake also significantly increased the occurrence of gastroesophageal reflux.
Conclusions: The rapid increase in cholecystokinin after water intake may be initiated by a feedback mechanism related to inflow of fatty chyme into the duodenum that inhibits gastric antral activity.