Effect of carbonated drinks on upper digestive tract sensations and physiology in healthy subjects.

The large use of sweetened carbonated beverages has fuelled several conflicting opinions about their effects on upper digestive tract functions. This matter has been poorly investigated with controlled trials. We aimed to evaluate the effect of sweetened carbonated drinks on upper digestive tract sensations and physiology in healthy subjects. Gastroesophageal reflux, gastric emptying and gallbladder contraction were studied in 13 healthy volunteers (7 women; median age 22 years; body mass index 23±3.5) by pH-impedance, octanoic acid breath test and ultrasound, respectively. The study was designed in a double-blind, randomized fashion with the subjects receiving 300 ml (150 before and 150 after meal) of two sets of beverage: a) still water, sweetened (sucrose 10%) water without or with increasing concentrations of carbon dioxide (2.0; 2.8 and 3.75 vol%; 7 subjects) and b) still water, sweetened (sucrose 10%) flavoured drink with (3.75 vol %) and without carbon dioxide (6 subjects). The study was scheduled performing on the first day the gastric emptying test (test meal of 480 Kcal: carbohydrates 32%, fat 44%, protein 24%) and a simultaneous esophageal pH-impedance. During the test a visual analogue score-based questionnaire assessing belching, satiety, epigastric burning/pain, bloating, heartburn, regurgitation and nausea was also performed before and every 15 minutes for 4 hours after meal. On the second day, milk-induced gallbladder contraction was studied with each of the beverages. Postprandial sensations were similar with any of the beverages tested. No differences were also found for gastric emptying and gallbladder contraction. However, 1 hour after meal, total numbers of gastroesophageal refluxes were significantly increased compared to basal values with all beverages tested. Only sweetened water without carbon dioxide determined a persistent increase in the number of refluxes two hours post meal. Although acid refluxes were prevalent, no differences were observed for gas and non acid-refluxes with any of the beverages. This study shows that increasing concentrations of carbon dioxide added to sweetened or flavored water does not significantly affect upper digestive tract functions and sensations in healthy subjects