Effects of inulin on faecal bifidobacteria in human subjects

Abstract

A controlled study with eight healthy free-living subjects was carried out, in which energy intake was adjusted to the individual energy requirements. On administration of inulin, blood lipids, the faecal microflora, short-chain fatty acids and accompanying gastrointestinal symptoms were characterized in order to investigate the long-term effect of inulin. During the run-in phase (8 d), subjects received a typical Western diet providing 45 % energy as fat and 40 % energy as carbohydrate. Subsequently, the subjects consumed a fat-reduced diet which provided 30 % energy as fat and 55 % energy as carbohydrate for a period of 64 d using inulin as a fat replacer. The amounts of inulin consumed by the subjects (up to 34 g/d) were based on individual energy requirements with the aim to keep the diet isoenergetic with that used in the run-in period. To assess the effects of inulin administration, a control study (run-in and intervention) was carried out in which subjects consumed the same diet but devoid of inulin during the whole course of the study. To investigate the effect of inulin on faecal flora composition total bacteria and bifidobacteria in the faeces were enumerated by in situ hybridization with 16S rRNA targeted oligonucleotide probes. Inulin significantly increased bifidobacteria from 9⋅8 to 11⋅0 log 10 /g dry faeces and caused a moderate increase in gastrointestinal symptoms such as flatulence and bloatedness, whereas blood lipids and short-chain fatty acids remained essentially unaffected. Inulin: Blood lipids: BifidobacteriaIn contemporary Western societies the lifestyle is characterized by a high dietary energy input due to a surplus of alimentary fat and reduced physical activity, leading to an increased incidence of adiposity. To meet dietary guidelines aimed at lowering fat consumption to prevent overweight and, at the same time, satisfying the consumer's enjoyment, the food industry has developed low-fat products using fat replacers. Such a fat replacer is inulin from chicory (Cichorium intybus) roots or Jerusalem artichoke (Helianthus tuberosus), which may help to improve the acceptability of low-fat food products by the consumer while also contributing to decreases in energy intake and body weight (Dreon et al. 1988;Grundy, 1991;Bruhn et al.

A double-blind placebo-controlled study to establish the bifidogenic dose of inulin in healthy humans

“…Previous human feeding studies have demonstrated the bifidogenic nature of both inulin and oligofructose. A variety of doses have been thus far reported effective in increasing faecal bifidobacteria in vivo, ranging from 4 to 40 g/day (Williams et al, 1994;Gibson et al, 1995;Buddington et al, 1996;Kleessen et al, 1997;Bouhnik et al, 1999;Kruse et al, 1999;Den Hond et al, 2000;Tuohy et al, 2001a;Bouhnik et al, 2004). Although microbial culture techniques were used in the majority of studies, results reported thus far on the prebiotic efficacy of inulin and oligofructose are in agreement with studies employing molecular methodologies of monitoring the prebiotic effect on the bacterial microflora (Tuohy et al, 2001a, b).…”

From Structure to Function: the Ecology of Host-Associated Microbial Communities

“…Although resistance to inulin and other prebiotics is low, it appears that the gut microbiota exhibits resilience following the conclusion of treatment. Kruse et al showed that 34 days after a 64-day treatment period, Bifidobacterium population sizes in 8 human subjects began to return to the levels observed before treatment (179). Studies of the mouse gut microbiota also suggest that prebiotic effects are short-lived.…”

Impact of cereal fibre on glucose-regulating factors

“…Interassay CV was 4.7%. Butyric acid was quantified by a modified version of a method described previously [31] and analysed by gas chromatography (HP 5890 II GC; Hewlett-Packard, Böblingen, Germany) using a capillary column (HP-20M; Hewlett-Packard, Palo Alto, CA, USA) and a flameionisation detector.…”