The interest of inulin-type fructans in the modulation of dysbiosis and metabolic alterations : experimental approach and nutritional interventions in humans
(2019)
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- Abstract
- Nowadays, obesity has reached an epidemic level worldwide. Overweight and obesity (body mass index >25 kg/m2 and >30 kg/m2, respectively) are associated with metabolic diseases including nonalcoholic fatty liver disease, type 2 diabetes, and cardiovascular diseases. Over the past decade, the gut microbiota was proposed as a biological component of obesity and related metabolic diseases. Diet is considered as a key driver of microbiome composition. Among nutrients able to modulate the gut microbiota, fermentable dietary fibers (DF) are generally considered as the most important food components prone to interact with the gut microbiome. Inulin-type fructans (ITF) have been widely studied for their prebiotic properties, when used as dietary supplement. However, very little is known about the effects of specific foodstuffs naturally rich in this type of fiber, such as vegetables. This PhD thesis is part of the Food4gut project (Excellence project financed by the Walloon Region) in which our aim was to unravel the interest for health of vegetables naturally rich in ITF. In this context, the objective of this work was to test the hypothesis that ITF as a dietary supplement, or as part of the diet, can positively impact host health through the modulation of the gut microbiota, particularly in the context of obesity. In the first part of this work, we demonstrated that ITF supplementation could improve postprandial hyperlipidemia in a murine model of diet-induced obesity. The mechanisms involve a potential improvement of lipid sensing in the jejunum, and an increase in fecal lipid excretion. In the second part of this thesis, we performed a single-group design trial in 26 healthy individuals who received a controlled diet based on ITF-rich vegetables for two weeks. We showed that ITF-rich vegetables consumption allows to reach a substantial amount of well-tolerated dietary fibers, and led to the improvement of food-related behavior in parallel with beneficial modifications of the gut microbiota composition and function. In the last part of this work, we evaluated the impact of inulin supplementation combined with a diet based on inulin-rich vegetables in obese patients in a randomized, simple-blinded, multicentric placebo-controlled trial. We first demonstrated that inulin-rich diet decreased body mass index and improves metabolic disorders after 3-months intervention. We also highlighted that the effects of inulin on metabolic disorders and gut microbiota were more prominent in patients who were not treated with the anti-diabetic drug metformin. In conclusion, this thesis demonstrates that ITF can be introduced in the diet and help to the management of weight and related metabolic diseases in the context of a healthy lifestyle.
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Hiel, S. (2019). The interest of inulin-type fructans in the modulation of dysbiosis and metabolic alterations : experimental approach and nutritional interventions in humans. https://hdl.handle.net/2078.5/60113