Gut microflora interactions with xylitol in the mouse, rat and man.

The influence of dietary xylitol on the quantity and quality of faecal microflora was studied in Wistar albino rats, CD-1 mice and healthy human volunteers. In animals, the effects of xylitol adaptation and of 4-wk xylitol feeding were examined. No major changes in the numbers of total aerobic or anaerobic bacteria, aerobic streptococci, anaerobic streptococci or yeasts were observed, although there was evidence of a dose-dependent decrease in the numbers of aerobic streptococci in the faeces. However, xylitol feeding caused a clear shift in the rodent faecal microbial population from Gram-negative to Gram-positive bacteria. In human volunteers a similar shift was observed even after a single 30-g oral dose of xylitol. All animals were capable of adapting to 20% dietary xylitol and an accompanying enhancement of the ability of caecal and faecal flora to utilize xylitol was observed.