In a study at the University of Illinois, recently published in the Journal of Applied Physiology, exercise-trained mice developed far fewer gallstones than mice who didn't exercise.
"For the first time, we have direct evidence that physical activity reduces gallstone formation, adding to the ever-increasing number of reasons that people should get more exercise," said Kenneth Wilund, assistant professor in kinesiology and community health.
In the study, 50 gallstone-susceptible mice ate a high-fat diet with cholic acid, which aids in absorbing cholesterol. (Gallstones form because bile cholesterol levels become so high that they solidify.) Two groups of mice were formed: one that ran on treadmills for 45 minutes a day, five days a week, and one that did not exercise.
After three months, the researchers removed the rodents' gallbladders and weighed the stones from each group. The gallstones in the sedentary group checked in at two and a half times the weight of the stones in the group that exercised. "You could see through the gallbladders in the exercise-trained group, whereas the gallbladders in the sedentary group were full of stones,' Wilund said.
Previous studies had suggested a link between physical fitness, lower cholesterol, and fewer gallstones, but laboratory experiments had not confirmed it. Mice are particularly useful as a model for human gallstone development, according to Wilund, because they have similar genes that regulate liver and bile cholesterol metabolism.
About 10 to 25 percent of American adults have gallbladder disease, which sends 800,000 people to the hospital every year.