Investigating the prebiotic and gas-generating effects of selected carbohydrates on the human colonic microflora

AIMS: To compare the fermentation of dietary carbohydrates with reference to their prebiotic and gas-generating capacity. METHODS AND RESULTS: Static anaerobic batch culture fermentations were carried out measuring gas generation and the prebiotic effect of five selected substrates (including various fructo-oligosaccharides, levan and maltodextrin). The largest gas producer was levan, whilst those showing no significant difference to Actilight included oligofructose and maltodextrin. Gas composition data showed that hydrogen and carbon dioxide were the two most quantitatively important gases. The substrate that appeared to have the best prebiotic effect in vitro was branched chain fructo-oligosaccharide (FOS), followed by oligofructose, Actilight and maltodextrin which each exerted a similar effect. The substrate with the least bifidogenic effect was levan. CONCLUSIONS: The composition and total gas generation data showed that there was much variation between and within donor inocula. Generally, the lower gas producers had a more selective fermentation whilst larger gas producers were less specific. SIGNIFICANCE AND IMPACT OF THE STUDY: The study of these three parameters enabled a more complete picture of carbohydrate breakdown to be drawn and hence highlighted the need for potential prebiotics to be more extensively evaluated in order to reduce negative side-effects such as gas distension.