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NutrInsight • Satiety: News Insights
The gut microbiota and obesity: evidence from animal models
Would it be possible to link the properties of dietary fibres which specifically modulate the gut microbiota with host functions related to obesity and overfeeding? Recent animal studies have provided evidence that alterations in the composition of the gut microbiota participate in the development of obesity and metabolic diseases [Neyrinck et al., 2012]. Such alterations might be consecutive to high fat intake. Figure 1 shows the decrease in gut bacteria induced in mice by a high fat diet in different experiments. There is evidence that prebiotics, a class of non-digestible/fermentable CHO that are prone to increase bifidobacteria, also decrease food intake in different animal models of obesity. Indeed, Figure 1 also shows that when animals fed a high fat diet were administered prebiotic fibres, such as inulin-type fructans (ITF) or arabinoxylans, the total count of bifidobacteria selectively increased [Cani et al., 2007; 2009b; Neyrinck et al., 2011]. The supplementation with arabinoxylans also decreased body weight gain and fat mass development, although it did not affect energy intake.
(a)
(b) 11.5
10.5
9.5
Total bacteria
**
HF HF-ITF
Total bacteria
*
HF HF-AX
Bifidobacteria * $
HF HF-ITF
Inulin-type fructans (ITF) (0,2g/day)
Arabinoxylans (AX)
11.5 11.0 10.5 10.0
9.5
9.5 9.0 8.5 8.0 7.5 7.0 6.5 6.0
9.5 9.0 8.5 8.0 7.5 7.0 6.5 6.0
CT
CT
CT
CT
Bifidobacteria
*
*$
*
HF HF-AX
Figure 1: Modulation of gut bacteria by dietary treatment in mice.
(a) Caecal bacterial content of total bacteria and bifidobacteria in mice fed a regular diet (CT), mice fed a high-fat diet (49.5%) (HF), and mice fed a high-fat diet plus 0.2 g/day inulin-type fructans (HF-ITF).
Source: Dewulf et al., 2011
(b) Lower level, caecal bacterial content of total bacteria and bifidobacteria in mice fed a standard diet (CT), mice fed a high-fat diet (HF), and mice a high-fat diet supplemented with arabinoxylans (10% w/w) (HF-AX). Bacterial quantities are expressed as Log10 (bacterial cells/g caecal content wet weight).
Source: Neyrinck et al., 2011
Data are mean ± S.E.M.
* p<0.05 from baseline; $ p<0.05 from HF
4.2 Interactionbetweenprebiotics,gutmicrobiota and host targets regulating appetite
Animal studies
Several hypotheses have been proposed to account for these appetite regulating effects of prebiotics on gut microbiota and host targets. Some have to do with the gut endocrine functions, including the role of glucagon-like peptide-1 (GLP-1), the implication of short chain free fatty acids (SCFA) following fermentation of prebiotics, and the differentiation of L-cells. Other hypotheses involve intestinal endocannabinoids.
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Log10 [DNA copies / total caecal content]
Log10 [DNA copies / total caecal content]
Log10 [DNA copies / total caecal content]
Log10 [DNA copies / total caecal content]