Leitzmann and his colleagues last year reported a similarly elevated risk of gallstones in sedentary men. Despite these and other gallbladder studies, the biological effect of exercise remains obscure. Exercise might limit stone formation by cutting blood concentrations of LDL cholesterol, the so-called bad cholesterol, Leitzmann says. High triglyceride concentrations in blood result in the liver adding cholesterol to bile-a digestive juice stored in the gallbladder. There, the saturated bile can form stones of hardened cholesterol, sometimes blocking bile's exit and causing pain.
Gallstones necessitate nearly all gallbladder removal surgery.
Copyright 1999, Science Service.