Background & Aims: Hydrogen sulfide is one of the main malodorous compounds in human flatus. This toxic gas also has been implicated in the pathogenesis of ulcerative colitis. Therefore, a treatment that reduces colonic H 2 S levels could be clinically useful in the treatment of flatus odor and of ulcerative colitis. In this study the ability of bismuth subsalicylate, a compound that binds H 2 S, to reduce H 2 S release in the colon, was tested. Methods: Homogenates made from human and rat feces were incubated with and without bismuth subsalicylate, and gas production was measured. Fecal samples from 10 healthy subjects were analyzed before and after ingestion of bismuth subsalicylate (524 mg four times a day) for 3–7 days. Results: Fecal homogenates showed a dose-dependent relationship between the concentration of bismuth subsalicylate and H 2 S release. Treatment of subjects with bismuth subsalicylate produced a >95% reduction in fecal H 2 S release. Conclusions: The ability of bismuth subsalicylate to dramatically reduce H 2 S could provide a clinically useful means of controlling fecal and/or flatus odor and of decreasing the putative injurious effects of H 2 S on the colonic mucosa.

GASTROENTEROLOGY 1998;114:923-929