Recherches sur le métabolisme du rumen chez les bovins tropicaux. Première partie : matériel, méthodes et étude de trois fourrages utilisés au Sénégal

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Prebiotic effects: metabolic and health benefits

The different compartments of the gastrointestinal tract are inhabited by populations of micro-organisms. By far the most important predominant populations are in the colon where a true symbiosis with the host exists that is a key for well-being and health. For such a microbiota, 'normobiosis' characterises a composition of the gut 'ecosystem' in which micro-organisms with potential health benefits predominate in number over potentially harmful ones, in contrast to 'dysbiosis', in which one or a few potentially harmful micro-organisms are dominant, thus creating a disease-prone situation. The present document has been written by a group of both academic and industry experts (in the ILSI Europe Prebiotic Expert Group and Prebiotic Task Force, respectively). It does not aim to propose a new definition of a prebiotic nor to identify which food products are classified as prebiotic but rather to validate and expand the original idea of the prebiotic concept (that can be translated in 'prebiotic effects'), defined as: 'The selective stimulation of growth and/or activity(ies) of one or a limited number of microbial genus(era)/species in the gut microbiota that confer(s) health benefits to the host.' Thanks to the methodological and fundamental research of microbiologists, immense progress has very recently been made in our understanding of the gut microbiota. A large number of human intervention studies have been performed that have demonstrated that dietary consumption of certain food products can result in statistically significant changes in the composition of the gut microbiota in line with the prebiotic concept. Thus the prebiotic effect is now a well-established scientific fact. The more data are accumulating, the more it will be recognised that such changes in the microbiota's composition, especially increase in bifidobacteria, can be regarded as a marker of intestinal health. The review is divided in chapters that cover the major areas of nutrition research where a prebiotic effect has tentatively been investigated for potential health benefits. The prebiotic effect has been shown to associate with modulation of biomarkers and activity(ies) of the immune system. Confirming the studies in adults, it has been demonstrated that, in infant nutrition, the prebiotic effect includes a significant change of gut microbiota composition, especially an increase of faecal concentrations of bifidobacteria. This concomitantly improves stool quality (pH, SCFA, frequency and consistency), reduces the risk of gastroenteritis and infections, improves general well-being and reduces the incidence of allergic symptoms such as atopic eczema. Changes in the gut microbiota composition are classically considered as one of the many factors involved in the pathogenesis of either inflammatory bowel disease or irritable bowel syndrome. The use of particular food products with a prebiotic effect has thus been tested in clinical trials with the objective to improve the clinical activity and well-being of patients with such disorders. Promising beneficial effects have been demonstrated in some preliminary studies, including changes in gut microbiota composition (especially increase in bifidobacteria concentration). Often associated with toxic load and/or miscellaneous risk factors, colon cancer is another pathology for which a possible role of gut microbiota composition has been hypothesised. Numerous experimental studies have reported reduction in incidence of tumours and cancers after feeding specific food products with a prebiotic effect. Some of these studies (including one human trial) have also reported that, in such conditions, gut microbiota composition was modified (especially due to increased concentration of bifidobacteria). Dietary intake of particular food products with a prebiotic effect has been shown, especially in adolescents, but also tentatively in postmenopausal women, to increase Ca absorption as well as bone Ca accretion and bone mineral density. Recent data, both from experimental models and from human studies, support the beneficial effects of particular food products with prebiotic properties on energy homaeostasis, satiety regulation and body weight gain. Together, with data in obese animals and patients, these studies support the hypothesis that gut microbiota composition (especially the number of bifidobacteria) may contribute to modulate metabolic processes associated with syndrome X, especially obesity and diabetes type 2. It is plausible, even though not exclusive, that these effects are linked to the microbiota-induced changes and it is feasible to conclude that their mechanisms fit into the prebiotic effect. However, the role of such changes in these health benefits remains to be definitively proven. As a result of the research activity that followed the publication of the prebiotic concept 15 years ago, it has become clear that products that cause a selective modification in the gut microbiota's composition and/or activity(ies) and thus strengthens normobiosis could either induce beneficial physiological effects in the colon and also in extra-intestinal compartments or contribute towards reducing the risk of dysbiosis and associated intestinal and systemic pathologies

Bien se nourrir et préserver la planète

National audienceOur diet has negative consequences on our health and that of the planet. There are solutions for a real food transition; but political will is lacking.Notre régime alimentaire a des conséquences négatives sur notre santé et sur celle de la planète. Des solutions existent pour faire naître une véritable transition alimentaire ; encore faut-il avoir la volonté politique de les mettre en place

Intérêt de la mise en relation des indicateurs lactiques avec la puissance maximale aérobie (PMA) obtenue lors de test à l’effort avec des paliers de 8 minutes sur cycloergomètre par des cyclistes de haut niveau

Introduction: L’analyse des facteurs déterminants la performance en endurance est primordiale pour le sportif souhaitant programmer de façon optimale les entrainements qu’il effectue au cours de sa saison. À cette fin, les cyclistes réalisent des tests à l’effort que ce soit en laboratoire ou sur le terrain. Par conséquent, il est indispensable de trouver quels sont les paramètres lactiques qui permettent d’expliquer la performance lors de ces tests. Objectifs: L’objectif de ce mémoire est de mettre en évidence une relation entre des indicateurs lactiques et la puissance développée lors de tests à l’effort en laboratoire et lors de tests de terrain. Méthode: 78 hommes élites en cyclisme ont participé à un ou plusieurs tests à l’effort par palier de 8 minutes sur cycloergomètre dans le laboratoire du CAPS. La Puissance maximale aérobie (PMA), la consommation maximale d’oxygène (VO2max), la fréquence cardiaque (FC) et les seuils lactiques ont été mesurés. Ensuite, 32 sujets issus de la première étape ont réalisé les tests de terrain 5 (P5) et 20 minutes (P20). Pendant ces tests, la puissance moyenne a été mesurée. Résultats: PDmax est corrélé à la PMA (r =0.944) ainsi qu’à P5 (r =0.770) et P20 (r =0.824); (p<0.001). Discussion: PDmax est une méthode fiable pour déterminer le seuil lactique d’un athlète. En effet, elle est mieux corrélée à la PMA, P5 et P20 que six autres méthodes de détermination de seuil lactique. Conclusion: PDmax semble être une méthode fiable pour expliquer la performance lors de tests en laboratoire et lors de tests de terrain.Master [120] en sciences de la motricité, orientation éducation physique, Université catholique de Louvain, 201

Eating well and saving the planet

Notre régime alimentaire a des conséquences négatives sur notre santé et sur celle de la planète. Des solutions existent pour faire naître une véritable transition alimentaire ; encore faut-il avoir la volonté politique de les mettre en place.Our diet has negative consequences on our health and that of the planet. There are solutions for a real food transition; but political will is lacking