Effect of lactulose on biliary lipid composition

Lactulose: Patient- and dose-dependent prebiotic properties in humans

Lactulose is a disaccharide used in clinical practice since 1957 and has since been tested in the treatment of many human disorders, including chronic constipation, hepatic encephalopathy, and chronic kidney disease. Its mode of action is based on the lactulose fermentation by intestinal microbiota. Based on in silico, in vitro and in vivo studies we comprehensively review here the impact of lactulose on human gut/fecal and vaginal microbiota composition and both fecal and blood metabolomes. However, both in vitro and in vivo studies summarized in this review have revealed that the effects of lactulose on human microbiota composition are both patient- and dose-dependent. This highlights the need of heterogeneity indication in clinical trials.

Effects of lactulose and lactitol on colonic microflora and enzymatic activity

The effects of lactulose and lactitol (2 x 10 g/d) were studied in 36 healthy volunteers in comparison to placebo. All parameters studied were affected by both treatments, lactulose in general leading to more pronounced changes compared to lactitol. Probiotic bacteria were increased, and putrefactive bacteria and potential pathogens were significantly reduced. These variations in colonic flora had the following consequences: (i) a reduced activity of pro-carcinogenic enzymes: azoreductase, 7 alpha-dehydroxylase, beta-glucuronidase, nitroreductase and urease activity; (ii) a global increase of short-chain fatty acids in faeces; (iii) an effect on pH and moisture of faeces, and (iv) also on aromatic compounds such as phenol, cresol, indole and skatol. The findings suggest that lactulose and lactitol are not comparable in their effect on the colonic microflora, its metabolism, and the consequent probiotic effects on human health. The differences found may also be of clinical relevance suggesting that neither compound is equipotent.

Effect of lactulose and fiber-rich diets on bile in relation to gallstone disease: an update

The primum movens in cholesterol gallstone formation is hepatic cholesterol hypersecretion and chronic supersaturation of bile. From this event a cascade of contributing factors can be differentiated: (i) Motility defects with impaired gallbladder contractility and gallbladder stasis, but also with small and large intestinal hypomotility. (ii) Multiple biochemical defects in gallbladder bile with increased biliary proteins, increased deoxycholic acid and rapid crystallization of biliary cholesterol from supersaturated unstable vesicles. There is considerable evidence that slow intestinal and colonic transit can increase the deoxycholic acid pool size and biliary cholesterol saturation. Changes in intestinal transit influence the anaerobic bacterial enzymatic biotransformation of conjugated cholate to more hydrophobic deoxycholate. This leads to biliary cholesterol hypersecretion and gallstone formation. Prokinetic drugs or administration of lactulose or fiber products like bran can change the slow intestinal transit favourably with subsequent reduction in deoxycholic acid formation and cholesterol saturation of bile. Whether these applications are indeed of value in the long-term prevention of gallstone disease, however, is doubtful, since fiber-rich diet in prevention of gallstone recurrence after complete gallstone dissolution was not successful.