EFFECTS OF LACTULOSE AND LACTITOL ON COLONIC MICROFLORA AND ENZYMATIC-ACTIVITY

The effects of lactulose and lactitol (2x10 g/d) were studied in 36 he althy volunteers in comparison to placebo. All parameters studied were affected by both treatments, lactulose in general leading to more pro nounced changes compared to lactitol. Probiotic bacteria were increase d, and putrefactive bacteria and potential pathogens were significantl y reduced. These variations in colonic flora had the following consequ ences: (i) a reduced activity of pro-carcinogenic enzymes: azoreductas e, 7 alpha-dehydroxylase, beta-glucuronidase, nitroreductase and ureas e activity; (ii) a global increase of short-chain fatty acids in faece s (iii) an effect an pH and moisture of faeces, and (iv) also on aroma tic 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 probiot ic effects on human health. The differences found may also be of clini cal relevance suggesting that neither compound is equipotent.