Gallbladder dynamics in response to various meals: is dietary fat restriction necessary in the management of gallstones?

An estimated 20 million Americans have gallstones the majority asymptomatic. Yet traditionally many are often placed on low-fat or fat-free diets, presumably to reduce the risk of biliary colic. To assess the gallbladder dynamics in response to various meals, we studied 15 subjects (ages 21-54), each on 4 separate days. After an overnight fast, each subject was given, at random, either a breakfast containing greater than 30 g fat, less than 15 g fat, totally free of fat, or an infusion of C-terminal octapeptide of cholecystokinin. Gallbladder ejections at regular time intervals were measured using real time ultrasonography and the sum of cylinders technic corrected for the gallbladder shape. Considerable variability in the gallbladder dynamics and time response was noted with all the stimuli. However, among various meals, there were no statistically significant differences in the mean maximum ejection fraction or the mean maximum ejection time (p greater than 0.10). The mean maximum ejection fraction after cholecystokinin was somewhat greater (0.01 less than p less than 0.05) than that after meals, but the mean maximum ejection time was similar (p greater than 0.10). We conclude that the gallbladder dynamics in response to various meals are independent of a meal's fat content. Since the passage of gallstones into the cystic or common duct (biliary colic) is a random event unrelated to the type of food, fat-restricted diets offer no significant therapeutic advantage in the management of the large population with asymptomatic gallstones.