AbstractLactobacillus acidophilusis considered to possess health-promoting attributes. These include anticarcinogenic and hypocholesterolemic properties and antagonistic action against intestinal and food-bome pathogens.L acidophiluscan also survive the hostile environment and establish in the complex ecosystem of the gastrointestinal tract. Therefore, the beneficial effects of ingestingL. acidophilusaccrue over a longer period than those organisms that cannot colonize the gut. However, the exact mechanisms of these attributes are not known. Presumably, the anticarcinogenic activity may be attributed to production of compounds and/or conditions that inhibit the proliferation of tumor cells, suppression of microorganisms that convert procarcinogens to carcinogens, and degradation of carcinogens formed. The hypocholesterolemic effect is probably exerted by inhibition of 3-hydroxy-3-methylglutaryl CoA reductase, which is a rate-limiting enzyme in endogenous cholesterol biosynthesis in the body and by promoting the excretion of dietary cholesterol in feces as a result of coprecipitation in the presence of deconjugated bile acids in the intestine and/or adsorption by the organisms. The antagonistic effect against pathogens and other organisms is possibly mediated by competition for nutrients and adhesion sites, formation of metabolites such as Organic acids, hydrogen peroxide, and production of antibiotic-like compounds and bacteriocins.