Soluble dietary fiber protects against cholesterol gallstone formation

BACKGROUND: Epidemiological studies have suggested that soluble dietary fibers are hypocholesterolemic and may inhibit cholelithiasis. METHODS: Thirty prairie dogs were placed on a cholesterol-supplemented lithogenic diet. Ten animals received 5% psyllium (PSY) and 10 animals received 5% cellulose. After 6 weeks all gallbladders were inspected for stones; blood and bile were collected for analysis. RESULTS: Cholesterol stones were present in 8 of 10 of the control animals, in 6 of 10 of the cellulose group, and 3 of 10 of the PSY animals (P <0.05). Concentrations of cholesterol and chenodeoxycholic acid (CDCA) were significantly lower in the PSY group compared with controls (0.49 versus 0.88 mM and 4.2 versus 9.2 mM, respectively) leading to a significant reduction in the cholesterol saturation index (0.62 versus 1.2). CONCLUSIONS: A dietary soluble fiber (PSY) inhibits cholesterol stone formation by reducing the biliary cholesterol saturation index. This protective effect is associated with a selective decrease in biliary cholesterol and CDCA.