Relationships between transit time in man and in vitro fermentation of dietary fiber by fecal bacteria

Abstract

Objective: To assess the effects of drug-induced changes in mean transit time (MTT) on the activity of human fecal¯ora in vitro. Methods: The activity of fecal¯ora was estimated by the ability of a fecal inoculum to ferment a substrate (beet ®ber) in vitro in a batch system for 24 h. The inoculum was collected from 8 healthy volunteers studied during three 3-week randomized periods, who received a controlled diet alone (control period) or the same diet with either cisapride or loperamide. Cisapride and loperamide were adjusted in order to halve and double MTT measured during the control period. At the end of each period, the percentage disappearance of the initial added substrate and the concentration and the pro®le of short-chain fatty acids (SCFAs), were determined. Results: In the control period, the pH of the inoculum and SCFA concentration were inversely related to MTT (P 0.0001). Individual SCFA production was also signi®cantly related to MTT (P`0.01). Cisapride-reduced transit time was associated with a signi®cant rise in the concentrations of total SCFAs (P`0.05), propionic and butyric acids (P`0.05) and the percentage substrate disappearance (P`0.05). Inverse relations were observed during the loperamide period. Moreover, MTT was inversely related to the percentage substrate disappearance (P`0.001), SCFA production (P`0.001) and butyrate production (P`0.0005). Conclusion: Changes in MTT alter bacterial activity and modify the bacterial pathways affecting the proportion of individual SCFAs. Sponsorship:

Short-chain fatty acids in control of body weight and insulin sensitivity

“…10,[35][36][37][38][39] Consistent with this observation, a cisaprideinduced reduction in gut transit time in humans was associated with an increased in vitro production of the major SCFA, as measured by the ability of individuals faecal inoculum to ferment dietary fibres in vitro. 39 …”

“…27,33,34 During increased speed of transit through the colon, substrates available for microbial fermentation are diminished, which might lead to reduced Key points ■ Short-chain fatty acids (SCFA), which are derived from gut microbial fermentation of indigestible foods, have important metabolic functions and are crucial for intestinal health ■ The discovery of SCFA receptors in many different tissues highlights that SCFA are involved in the crosstalk between the gut and peripheral tissues ■ In addition to their role in gut health and as signalling molecules, SCFA might enter the systemic circulation and directly affect substrate metabolism and function of peripheral tissues ■ SCFA might increase intestinal energy harvesting and promote the development of obesity, but could also increase energy expenditure and anorexic hormone production, as well as improving appetite regulation ■ Increasing evidence supports a beneficial role for SCFA in adipose tissue, skeletal muscle and liver substrate metabolism and function, thereby contributing to improved insulin sensitivity ■ Well-controlled human intervention studies investigating the role of SCFA and differential SCFA availability on gut and systemic metabolic health are eagerly awaited SCFA production. 10,[35][36][37][38][39] Furthermore, differences in substrate availability, due to altered gut transit times could shift microbial composition and concen trations, which might lead to alterations in microbial SCFA production. 10,[35][36][37][38][39] Consistent with this observation, a cisaprideinduced reduction in gut transit time in humans was associated with an increased in vitro production of the major SCFA, as measured by the ability of individuals faecal inoculum to ferment dietary fibres in vitro.…”

“…10,[35][36][37][38][39] Furthermore, differences in substrate availability, due to altered gut transit times could shift microbial composition and concen trations, which might lead to alterations in microbial SCFA production. 10,[35][36][37][38][39] Consistent with this observation, a cisaprideinduced reduction in gut transit time in humans was associated with an increased in vitro production of the major SCFA, as measured by the ability of individuals faecal inoculum to ferment dietary fibres in vitro. 39 …”

Methane on Breath Testing Is Associated with Constipation: A Systematic Review and Meta-analysis

“…In addition, the systematic review identified eight papers that examined intestinal transit in the presence of methane (Table 2) [39][40][41][42][43][44][45][46]. While studies could not be combined for meta-analysis due to markedly different techniques (bowel frequency, orocecal, colonic, and whole gut transit time), all eight studies demonstrated that the presence of methane was associated with significant slowing of intestinal transit irrespective of the measure used.…”

Stimulation of Indigenous Lactobacilli by Fermented Milk Prepared with Probiotic Bacterium, Lactobacillus delbrueckii subsp. bulgaricus Strain 2038, in the Pigs

“…Digesta kinetics is modified by fermented milk (23) and the cell component of LAB (27). The modification of digesta retention time should affect the bacterial composition, then the fermentation pattern (28). Further in vivo study using appropriate control materials such as unfermented milk will be required for elucidating the specific mechanism of Ldb to stimulate and/or inhibit the growth of indigenous lactobacilli.…”