Resistant starch modifies gut microflora and microbial metabolism in humanflora-associated rats inoculated with faeces from Italian and UK donors

The effect of sucrose and resistant starch ('CrystaLean' - a retrograded, a mylose starch) on human gut microflora and associated parameters was studie d in human flora-associated (HFA) rats, colonized with microfloras from UK or Italian subjects, to determine whether such floras were affected differe ntly by dietary carbohydrates. Consumption of the resistant starch diet res ulted in significant changes in four of the seven main groups of bacteria e numerated. In both the UK and Italian flora-associated rats, numbers of lac tobacilli and bifidobacteria were increased 10-100-fold, and there was a co ncomitant decrease in enterobacteria when compared with sucrose-fed rats. T he induced changes in caecal microflora of both HFA rat groups were reflect ed in changes in bacterial enzyme activities and caecal ammonia concentrati on. Although it had little effect on caecal short-chain fatty acid concentr ation, CrystaLean markedly increased the proportion of n-butyric acid in bo th rat groups and was associated with a significant increase in cell prolif eration in the proximal colon of the Italian flora-associated rats. CrystaL ean appeared to play a protective role in the colon environment, lowering c aecal ammonia concentration, caecal pH and beta-glucuronidase activity.