Influence of the content of liquid test meals on gastric emptying assessed by <SUP>13</SUP>C-acetate breath test

Abstract

Background: 13C-acetate breath test (ABT) has been proposed as a noninvasive and nonradioactive technique for measuring gastric emptying. A variety of test meals have been used for the ABT. Since a standardized test meal that is easily prepared and inexpensive would be helpful for using ABT as a clinical test, we use a liquid test meal in screening for gastrointestinal motility disorders. Studies comparing ABT results after administrating a variety of liquid test meals are lacking. The aims of this study were to compare the gastric emptying indexes obtained by ABT after ingestion of three kinds of test meals with different fat and caloric content.Patients and Methods: Ten healthy subjects, 7 women and 3 men, aged 25-51 years, volunteered for this study. None of them complained of gastrointestinal symptoms, was taking any drugs or was a smoker. Each subject was studied three times, with a 1-week interval between tests. RACOL (200 kcal, protein 8.76 g, fat 4.46 g, glucose 31.24 g), Ensure Liquid (200 kcal, protein 7.04 g, fat 7.04 g, glucose 27.4 g), and Ensure Hi (300 kcal, protein 10.56 g, fat 10.56 g, glucose 41.2 g) were given in randomized order. Breath samples were collected at 5, 10, 15, 20, 30, 40, 50, 60, 75, 90, 105, 120, 135, 150, 165, 180, 210, and 240 min. 13C was measured as the 13CO2/12CO2 isotope ratio and was expressed as delta over baseline per mil. The results of ABT, gastric emptying, were expressed as the time of peak excretion (Tmax) and half emptying time (T1/2) calculated using the Solver procedure in Excel 2000 (Microsoft).Results: The mean values of Tmax were 0.99, 0.85, and 1.05 hours after ingestion of RACOL, Ensure Liquid, and Ensure Hi, respectively. The mean values of T1/2 were 1.53, 1.35, and 1.65 hours, respectively. Increasing the meal caloric content resulted in significantly longer half emptying time, whereas increasing the fat content had little effect on gastric emptying assessed by ABT using liquid test meals.Conclusions: In healthy subjects, caloric intake is a major determinant of gastric emptying rate.