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.

The myofibrillar protein synthetic response to the ingestion of 35 g casein is greater than after an equal amount of wheat protein. Ingesting a larger amount of wheat protein (i.e., 60 g) substantially increases myofibrillar protein synthesis rates in healthy older men. This trial was registered at clinicaltrials.gov as NCT01952639.

Background: Short-chain fructooligosaccharides (scFOS) have beneficial effects in subjects with minor digestive complaints, but the potential mechanisms involved have not been elucidated. The aim of the study was to evaluate changes in rectal sensitivity related to the clinical effects of scFOS in a selected group of patients with irritable bowel syndrome (IBS) and rectal hypersensitivity. Methods:In 79 IBS patients (defined by Rome III criteria) with rectal hypersensitivity (defined as discomfort threshold ≤44 g) a parallel, placebo-controlled, randomized, and double-blind study was performed to assess the effects of dietary supplementation) with scFOS vs placebo for 4 weeks on rectal sensitivity (primary outcome: tolerance to increasing wall tension applied by a tensostat), clinical outcomes (IBS, anxiety/depression and quality of life scores) and composition of fecal microbiota.Key Results: Rectal discomfort threshold, and IBS and quality of life scores, significantly improved during treatment, but in a similar manner in both scFOS and placebo groups; a post-hoc analysis showed that the effect of scFOS on rectal sensitivity was more pronounced in constipation-predominant-IBS patients (P=.051 vs placebo). Contrary with placebo, scFOS significantly reduced anxiety scores and increased fecal Bifidobacteria (P<.05 for both) without modifying other bacterial groups. Conclusions & Interfences:The effect of scFOS on anxiety may be related to modulation of the gut microbiota; demonstration of effects of scFOS on rectal sensitivity may require higher doses and may depend on the IBS subgroup. K E Y W O R D Sanxiety, fibers, fructooligosaccharides, irritable bowel syndrome, microbiota

Peripartum nutrition is crucial for developing the immune system of neonates. We hypothesized that maternal short-chain fructooligosaccharide (scFOS) supplementation could accelerate the development of intestinal immunity in offspring. Thirty-four sows received a standard or a scFOS supplemented diet (10 g scFOS/d) for the last 4 weeks of gestation and the 4 weeks of lactation. Colostrum and milk immunoglobulins (Ig) and TGFβ1 concentrations were evaluated on the day of delivery and at d 6 and d 21 postpartum. Piglet intestinal structure, the immunologic features of jejunal and ileal Peyer's patches, and mesenteric lymph node cells were analysed at postnatal d 21. Short-chain fatty acid concentrations were measured over time in the intestinal contents of suckling and weaned piglets. Colostral IgA (P<0.05) significantly increased because of scFOS and TGFβ1 concentrations tended to improve (P<0.1). IFNγ secretion by stimulated Peyer's patch and mesenteric lymph node cells, and secretory IgA production by unstimulated Peyer's patch cells were increased (P<0.05) in postnatal d 21 scFOS piglets. These differences were associated with a higher proportion of activated CD25+CD4α+ T cells among the CD4+ helper T lymphocytes (P<0.05) as assessed by flow cytometry. IFNγ secretion was positively correlated with the population of activated T lymphocytes (P<0.05). Total short-chain fatty acids were unchanged between groups during lactation but were higher in caecal contents of d 90 scFOS piglets (P<0.05); specifically propionate, butyrate and valerate. In conclusion, we demonstrated that maternal scFOS supplementation modified the intestinal immune functions in piglets in association with increased colostral immunity. Such results underline the key role of maternal nutrition in supporting the postnatal development of mucosal immunity.

A comparative, randomised, double-blind trial was performed in the medical departments of five hospitals to study the effects of regular consumption of short-chain fructo-oligosaccharides (sc-FOS) on the digestive comfort of subjects with minor functional bowel disorders (FBD). In step 1, 2235 subjects were questioned to assess the incidence and intensity of digestive disorders. In step 2, 105 of these patients diagnosed with minor FBD were randomised into two groups to receive either 5 g sc-FOS or 5 g placebo (sucrose and maltodextrins) per d over a 6-week period. The incidence and intensity of digestive disorders were assessed at the end of the treatment period (day 43) using the step 1 questionnaires. A qualityof-life questionnaire was also completed at the start and end of the treatment period to assess potential effects on well-being and social performance. In step 1, 44 % of the subjects questioned presented FBD, of whom 57·1 % suffered from minor FBD. In step 2, on day 43, the intensity of digestive disorders decreased by 43·6 % in the sc-FOS group v. a 13·8 % increase in the placebo group (P¼0·026). Symptoms were experienced less frequently by 75·0 % of subjects in the sc-FOS group, while 53·8 % of controls experienced no change (P¼0·064). Using the functional digestive disorders quality of life questionnaire, the discomfort item scores increased in the sc-FOS group (P¼ 0·031). However, expressed as change in quality of life (improvement, worsening or unchanged), daily activities were significantly improved in the sc-FOS group (P¼ 0.022). Regular consumption of sc-FOS may improve digestive comfort in a working population not undergoing medical treatment. Short-chain fructo-oligosaccharides: Quality of life: Functional bowel disordersFunctional bowel disorders (FBD) are diagnosed on the basis of characteristic symptoms in the digestive system persisting for at least 12 weeks over the last 12 months in the absence of any structural or biochemical explanation 1 . The five main symptoms reported by patients are abdominal bloating, rumbling, transit disorders (occasional constipation and/or diarrhoea, possibly alternating), abdominal pains and flatulence. FBD have been reported as being chronic, non-life-threatening conditions, but having a marked impact on daily activities, wellbeing and social performance, even during symptom-free periods, mainly due to apprehension about impending pain 2 -6 .These functional disorders, influenced by psychological and environmental factors 7 , are common, with a reported prevalence of up to 61 % in the French population aged over 15 years 6 . Functional disorders thus lead to a high number of general medical and gastroenterology consultations, respectively accounting for 10 and 50 % of all medical consultations 4 -6,8 -11 . However, two-thirds of subjects with FBD never consult a doctor for their disorder. A nutritional approach therefore appears a good alternative to medication for subjects with minor FBD or individuals rejecting medical therapy. Amongst the few already ...