Physical activity, biliary lipids, and gallstones in obese subjects

OBJECTIVE: Gallstone disease is a major source of morbidity in the US. Reduced physical activity has been shown to be a risk factor for gallstone formation in recent studies; however, the mechanisms to explain how physical activity may protect against gallstone formation have not been well elucidated. We investigated the relationships between physical activity, biliary lipids, and gallstone disease. METHODS: Three types of habitual physical activity (work, sport, and leisure time), biliary lipids, and serum lipids were estimated or measured in 53 obese subjects undergoing gastric bypass surgery. These physical activities were defined as activity at work, sport activity during leisure time, and activity during leisure time excluding sports, respectively. RESULTS: We found that sport activity but not work and leisure time activities was inversely associated with gallstone disease. Lower levels of biliary bile salts and percent biliary bile salts (expressed in percentage of total biliary lipids) and higher levels of percent cholesterol were also found to be associated with gallstone disease. A lower level of sport activity appeared to be associated with higher levels of biliary cholesterol, percent biliary cholesterol, and serum triglycerides. CONCLUSION: Our findings demonstrate that low levels of physical activity are associated with gallstone formation. Our study also suggests that a possible mechanism for the protective effect of physical activity on gallstone formation is the lowering of biliary cholesterol levels, thus preventing cholesterol from precipitating in the bile. In addition, our data suggest that sport activity is a more effective form of physical activity than working and leisure activities in the prevention of gallstone disease.