Meal composition influences postprandial sensations independently of valence and gustation.

BACKGROUND: Palatability of meals with identical composition has been shown to influence postprandial sensations. Our aim was to determine to what extent meal composition influences postprandial sensations independently of palatability. METHODS: Randomized, crossover, double-blind trial comparing the postprandial responses to a low-fat vs a high-fat test meal, with the same physical and organoleptic characteristics (taste, smell, texture, color, and temperature). The test meal consisted in 150 g hummus containing either 17.7 g fat (low-fat) or 22.3 g fat (high-fat), 19.8 g toasts, 120 mL water and 50 g apple puree. In 12 non-obese healthy men, palatability, homeostatic sensations (hunger/satiety, fullness) and hedonic sensations (digestive well-being, mood) were measured on 10 cm scales before and during the 60-min postprandial period. Comparisons between meals were performed with a two-way repeated measures ANCOVA with premeal data as co-variate. KEY RESULTS: Both test meals were rated equally palatable (palatability scores 3.8 ± 0.3 low-fat, 3.3 ± 0.2 high-fat; P = .156). As compared to the high-fat meal, the low-fat meal induced more satisfaction (meal effect on well-being F(1,21) = 4.92; P = .038) and tended to improve mood (meal effect F(1,21) = 3.02; P = .064), and this was associated with a non-significant decrease in satiety (meal effect F(1,21) = 2.29; P = .145) and fullness (meal effect F(1,21) = 1.57; P = .224). CONCLUSIONS AND INFERENCES: The composition of meals with equal palatability influences postprandial satisfaction, even without significant impact on homeostatic sensations, although an effect on homeostatic sensations has not been excluded. These conditioning factors may have clinical implications in patients with impaired meal tolerance or meal-related symptoms.

Biogastronomy: Factors that determine the biological response to meal ingestion.

BACKGROUND: The biological response to a meal includes physiological changes, primarily related to the digestive process, and a sensory experience, involving sensations related to the homeostatic control of food consumption, eg, satiety and fullness, with a hedonic dimension, ie associated with changes in digestive well-being and mood. The responses to a meal include a series of events before, during and after ingestion. While much attention has been paid to the events before and during ingestion, relatively little is known about the postprandial sensations, which are key to the gastronomical experience. PURPOSE: The aim of this narrative review is to provide a comprehensive overview and to define the framework to investigate the factors that determine the postprandial experience. Based on a series of proof-of-concept studies and related information, we propose that the biological responses to a meal depend on the characteristics of the meal, primarily its palatability and composition, and the responsiveness of the guest, which may be influenced by multiple previous and concurrent conditioning factors. This information provides the scientific backbone to the development of personalized gastronomy.

Effects of meal palatability on postprandial sensations.

BACKGROUND: Food palatability has been shown to influence satiation and meal consumption; our aim was to determine its effects on postprandial satisfaction, ie digestive well-being (primary outcome), and homeostatic sensations (satiety, fullness). METHODS: Randomized, cross-over trial comparing the postprandial responses to conventional (potato-cheese cream followed by vanilla cream) vs unconventional test meals (mixture of both creams) with identical composition and physical characteristics (color, texture, consistency, temperature) but distinctively different palatability. In 22 non-obese healthy men sensations were measured on 10 cm scales before and during the 60-min postprandial period (-5 to +5 score scales for palatability, satiety, well-being, and mood, and 0-10 score scales for fullness and discomfort). Comparisons between meals were performed with a 2-way repeated measures ANCOVA with premeal data as co-variate. KEY RESULTS: As compared to the palatable conventional meal, the unconventional meal was rated unpalatable (-1.8 ± 0.4 score vs 2.8 ± 0.1 score potato cream and 2.9 ± 0.2 vanilla cream; P < .001 for both), induced significantly more fullness sensation [meal effect F (1, 19) = 7.389; P = .014] but had less effect on digestive well-being [meal effect F (1, 19) = 47.016; P < .001] and mood [meal-effect F (1, 19) = 6.609; P = .019]. The difference in satiety was not significantly different. CONCLUSION & INFERENCES: Meal palatability influences the postprandial experience: it bears a direct relation to the hedonic response (well-being/mood) but an inverse relation to homeostatic sensations (fullness). These relations could be applicable to influence eating behavior, because at equal conditions, more palatable meals induce less fullness but more satisfaction, and vice-versa.

Comparison between small bowel manometric patterns and full-thickness biopsy histopathology in severe intestinal dysmotility.

BACKGROUND: Intestinal manometry is the current standard for direct evaluation of small bowel dysmotility. Patients with abnormal motility can either be diagnosed of pseudo-obstruction when there are radiological findings mimicking mechanical intestinal obstruction or of enteric dysmotility when these findings are absent. The aim of the present study was to prospectively compare small bowel manometric abnormalities with histopathological findings in intestinal full-thickness biopsies in patients with severe dysmotility disorders. METHODS: We investigated 38 patients with intestinal manometry and a subsequent full-thickness intestinal biopsy. Manometric recordings were read by 4 investigators and a diagnostic consensus was obtained in 35 patients. Histopathological analysis, including specific immunohistochemical techniques of small bowel biopsies was performed and compared to manometric readings. KEY RESULTS: Patients with abnormal intestinal manometry had abnormal histopathological findings in 73% of cases. However, manometric patterns did not match with the specific neuromuscular abnormalities. Among patients with a neuropathic manometry pattern and abnormal histopathology, only 23% had an enteric neuropathy, whereas 62% had neuromuscular inflammation, and 15% an enteric myopathy. On the other hand, patients with a myopathic manometry pattern all had abnormal histopathology, however, none of them with signs of enteric myopathy. CONCLUSION & INFERENCES: Small bowel dysmotility detected by intestinal manometry is often associated with abnormal neuromuscular findings in full-thickness biopsies. However, there is no correlation between the specific manometric patterns and the histopathological findings.

Education of the postprandial experience by a sensory-cognitive intervention.

BACKGROUND: Ingestion of a meal induces homeostasis-related sensations (satiety/fullness) that have a hedonic dimension (satisfaction/mood). We have previously shown that a previous physiological intervention, a meal preload, influences the responses to a subsequent meal, specifically: it increases satiety/fullness and decreases satisfaction. We now wished to determine the differential effects of education on the homeostatic and hedonic postprandial experience. METHODS: Randomized, parallel study comparing the effect of real vs sham education on the responses to a probe meal. In two groups of healthy subjects (n = 14 each), homeostatic (satiety, fullness) and hedonic sensations (digestive well-being, mood) in response to a probe meal (250 mL soup, 25 g bread) were measured on 2 separate days before and after a single sensory-cognitive educational intervention (taste recognition test of supra- and sub-threshold tastands for real and sham education, respectively). KEY RESULTS: Before education, in both groups the probe meal induced homeostatic sensations (satiety, fullness) with a positive hedonic dimension (increased digestive well-being and mood). In contrast to sham education, real education enhanced both homeostatic and hedonic responses to the probe meal (P < .05 vs sham education for all). CONCLUSIONS AND INFERENCES: Education modifies the subjects' receptiveness and influences the responses to a meal, not only the hedonic postprandial experience, but also homeostatic sensations. Since homeostatic and hedonic responses are dissociable, education might be tailored to target different conditions.

Colonic gas homeostasis: Mechanisms of adaptation following HOST-G904 galactooligosaccharide use in humans.

BACKGROUND: We have shown that a galactooligosaccharide prebiotic administration (HOST-G904) initially increased intestinal gas production and this increase declined back to baseline after 2 week administration. Our aim was to determine the mechanism of microbiota adaptation; i.e., to determine whether the net reduction is due to decreased overall production or increased gas consumption. METHODS: In 10 healthy subjects, intestinal gas production and intraluminal disposal was measured before, at the beginning and after 2 week of HOST-G904 prebiotic administration. Anal gas was collected for 4 hour after a probe meal. Paired studies were performed without and with high-rate infusion of exogenous gas (24 mL/min) into the jejunum to wash-out the endogenous gas produced by bacterial fermentation. The exogenous gas infused was labeled (5% SF6 ) to calculate the proportion of endogenous gas evacuated. KEY RESULTS: The volume of intestinal gas produced i.e., endogenous gas washed-out, increased by 37% at the beginning of HOST-G904 administration (P=.049 vs preadministration) and decreased down to preadministration level after 2 week administration (P=.030 vs early administration). The proportion of gas eliminated from the lumen before reaching the anus tended to increase after 2-week administration (87±3% vs 78±5% preadministration; P=.098). CONCLUSIONS & INFERENCES: Adaptation to regular consumption of HOST-G904 prebiotic involves a shift in microbiota metabolism toward low-gas producing pathways, with a non-significant increase in gas-consuming activity. Hence, regular consumption of HOST-G904 regulates intestinal gas metabolism: less gas is produced and a somewhat larger proportion of it is consumed.

Appetite influences the responses to meal ingestion.

BACKGROUND: We have previously shown that the postprandial experience includes cognitive sensations, such as satiety and fullness, with a hedonic dimension involving digestive well-being and mood. Preload conditioning has been shown to modulate appetite and food consumption under certain conditions, but its effects on the responses to meal ingestion are not clear. We hypothesized that appetite modulation by preload conditioning has differential effects on the cognitive and the emotive responses to meal ingestion. METHODS: The effects of preload conditioning (ingestion of a low- vs a high-calorie breakfast) on appetite and on the cognitive and emotive responses to a comfort probe meal ingested 2 hours later (ham and cheese sandwich with orange juice; 300 mL, 425 Kcal) was tested in healthy subjects (n=12) in a cross-over design. Sensations were measured at regular intervals 15 minutes before and 60 minutes after the probe meal. KEY RESULTS: As compared to the low-calorie breakfast, the high-calorie breakfast reduced basal hunger sensation and influenced the responses to the subsequent probe meal: it increased satiety (4.3±0.2 score vs 2.7±0.2 score; P<.001) and fullness (5.4±0.5 score vs 3.1±0.5; P<.001), but reduced the expected postprandial experience of digestive well-being after a palatable meal (1.3±0.7 score vs 3.0±0.3; P=.045). CONCLUSION AND INFERENCES: Appetite modulation by preload conditioning has differential effects on the cognitive and emotive responses to a meal. Preload conditioning of the postprandial experience may be applicable to dietary planning and prevention of postprandial symptoms.

Randomised clinical trial: the analgesic properties of dietary supplementation with palmitoylethanolamide and polydatin in irritable bowel syndrome.

BACKGROUND: Intestinal immune activation is involved in irritable bowel syndrome (IBS) pathophysiology. While most dietary approaches in IBS involve food avoidance, there are fewer indications on food supplementation. Palmithoylethanolamide, structurally related to the endocannabinoid anandamide, and polydatin are dietary compounds which act synergistically to reduce mast cell activation. AIM: To assess the effect on mast cell count and the efficacy of palmithoylethanolamide/polydatin in patients with IBS. METHODS: We conducted a pilot, 12-week, randomised, double-blind, placebo-controlled, multicentre study assessing the effect of palmithoylethanolamide/polydatin 200 mg/20 mg or placebo b.d. on low-grade immune activation, endocannabinoid system and symptoms in IBS patients. Biopsy samples, obtained at screening visit and at the end of the study, were analysed by immunohistochemistry, enzyme-linked immunoassay, liquid chromatography and Western blot. RESULTS: A total of 54 patients with IBS and 12 healthy controls were enrolled from five European centres. Compared with controls, IBS patients showed higher mucosal mast cell counts (3.2 ± 1.3 vs. 5.3 ± 2.7%, P = 0.013), reduced fatty acid amide oleoylethanolamide (12.7 ± 9.8 vs. 45.8 ± 55.6 pmol/mg, P = 0.002) and increased expression of cannabinoid receptor 2 (0.7 ± 0.1 vs. 1.0 ± 0.8, P = 0.012). The treatment did not significantly modify IBS biological profile, including mast cell count. Compared with placebo, palmithoylethanolamide/polydatin markedly improved abdominal pain severity (P < 0.05). CONCLUSIONS: The marked effect of the dietary supplement palmithoylethanolamide/polydatin on abdominal pain in patients with IBS suggests that this is a promising natural approach for pain management in this condition. Further studies are now required to elucidate the mechanism of action of palmithoylethanolamide/polydatin in IBS. ClinicalTrials.gov number, NCT01370720.

Relation between cognitive and hedonic responses to a meal.

BACKGROUND: Ingestion of a meal induces cognitive and hedonic sensations and our aim was to determine the relation between both dimensions. METHODS: In three groups of healthy non-obese men (n=10 per group) three types of meals with equivalent levels of palatability were tested: a liquid meal, a solid-liquid low-calorie meal, and a solid-liquid high-calorie meal. The cognitive and hedonic responses were measured on 10-cm scales before and during the 30-minute postprandial period. KEY RESULTS: The liquid meal induced a relatively strong cognitive response with satiation (4.7±0.7 score increment), fullness (3.3±0.7 score increment), and inhibition of desire of eating a food of choice; in contrast, its impact on sensation of digestive well-being and satisfaction was not significant (0.7±0.7 score increment). The high-calorie solid-liquid meal, with larger volume load and caloric content, induced much lower satiation (2.4±0.8 score increment; P=.041 vs liquid meal) and fullness sensation (1.3±0.6 score increment; P=.031 vs liquid meal), but a markedly higher level of satisfaction (2.7±0.4 score increment; P=.021 vs liquid meal); the low-calorie mixed meal had less prominent effects with significantly lower satisfaction (1.0±0.4 score increment; P=.039 vs high-calorie meal). CONCLUSIONS AND INFERENCES: The cognitive (satiation, fullness) and hedonic responses (satisfaction) to meals with equivalent levels of palatability, that is, equally likable, are dissociable. The characteristics of meals in terms of satiation and rewarding power could be adapted to specific clinical targets, whether nutritional supplementation or restriction.

Brain networks associated with cognitive and hedonic responses to a meal.

BACKGROUND: We recently reported interrelated digestive, cognitive, and hedonic responses to a meal. The aim of this study was to identify brain networks related to the hedonic response to eating. METHODS: Thirty-eight healthy subjects (20-38 age range) were evaluated after a 5-hour fast and after ingestion of a test meal (juice and warm ham and cheese sandwich, 300 mL, 425 kcal). Perceptual and affective responses (satiety, abdominal fullness, digestive well-being, and positive mood), and resting scans of the brain using functional MRI (3T Trio, Siemens, Germany) were evaluated immediately before and after the test meal. A high-order group independent component analysis was performed to investigate ingestion-related changes in the intrinsic connectivity of brain networks, with a focus on thalamic and insular networks. KEY RESULTS: Ingestion induced satiation (3.3±0.4 score increase; P<.001) and abdominal fullness (2.4±0.3 score increase; P<.001). These sensations included an affective dimension involving digestive well-being (2.8±0.3 score increase; P<.001) and positive mood (1.8±0.2 score increase; P<.001). In general, thalamo-cortical connectivity increased with meal ingestion while insular-cortical connectivity mainly decreased. Furthermore, larger meal-induced changes (increase/decrease) in specific thalamic connections were associated with smaller changes in satiety/fullness. In contrast, a larger meal-induced decrease in insular-anterior cingulate cortex connectivity was associated with increased satiety, fullness, and digestive well-being. CONCLUSIONS AND INFERENCES: Perceptual and emotional responses to food intake are related to brain connectivity in defined functional networks. Brain imaging may provide objective biomarkers of subjective effects of meal ingestion.

Metabolic adaptation of colonic microbiota to galactooligosaccharides: a proof-of-concept-study.

BACKGROUND: Prebiotics have been shown to reduce abdominal symptoms in patients with functional gut disorders, despite that they are fermented by colonic bacteria and may induce gas-related symptoms. AIM: To investigate changes in the metabolic activity of gut microbiota induced by a recognised prebiotic. METHODS: Healthy subjects (n = 20) were given a prebiotic (2.8 g/day HOST-G904, HOST Therabiomics, Jersey, Channel Islands) for 3 weeks. During 3-day periods immediately before, at the beginning and at the end of the administration subjects were put on a standard diet (low fibre diet supplemented with one portion of high fibre foods) and the following outcomes were measured: (i) number of daytime gas evacuations for 2 days by means of an event marker; (ii) volume of gas evacuated via a rectal tube during 4 h after a test meal; and (iii) microbiota composition by faecal Illumina MiSeq sequencing. RESULTS: At the beginning of administration, HOST-G904 significantly increased the number of daily anal gas evacuations (18 ± 2 vs. 12 ± 1 pre-administration; P < 0.001) and the volume of gas evacuated after the test meal (236 ± 23 mL vs. 160 ± 17 mL pre-administration; P = 0.006). However, after 3 weeks of administration, these effects diminished (11 ± 2 daily evacuations, 169 ± 23 mL gas evacuation). At day 21, relative abundance of butyrate producers (Lachnospiraceae) correlated inversely with the volume of gas evacuated (r = -0.52; P = 0.02). CONCLUSION: The availability of substrates induces an adaptation of the colonic microbiota activity in bacterial metabolism, which produces less gas and associated issues. Clinical trials.gov NCT02618239.

Colonic content: effect of diet, meals, and defecation.

BACKGROUND: The metabolic activity of colonic microbiota is influenced by diet; however, the relationship between metabolism and colonic content is not known. Our aim was to determine the effect of meals, defecation, and diet on colonic content. METHODS: In 10 healthy subjects, two abdominal MRI scans were acquired during fasting, 1 week apart, and after 3 days on low- and high-residue diets, respectively. With each diet, daily fecal output and the number of daytime anal gas evacuations were measured. On the first study day, a second scan was acquired 4 hours after a test meal (n=6) or after 4 hours with nil ingestion (n=4). On the second study day, a scan was also acquired after a spontaneous bowel movement. RESULTS: On the low-residue diet, daily fecal volume averaged 145 ± 15 mL; subjects passed 10.6 ± 1.6 daytime anal gas evacuations and, by the third day, non-gaseous colonic content was 479 ± 36 mL. The high-residue diet increased the three parameters to 16.5 ± 2.9 anal gas evacuations, 223 ± 19 mL fecal output, and 616 ± 55 mL non-gaseous colonic content (P<.05 vs low-residue diet for all). On the low-residue diet, non-gaseous content in the right colon had increased by 41 ± 11 mL, 4 hours after the test meal, whereas no significant change was observed after 4-hour fast (-15 ± 8 mL; P=.006 vs fed). Defecation significantly reduced the non-gaseous content in distal colonic segments. CONCLUSION & INFERENCES: Colonic content exhibits physiologic variations with an approximate 1/3 daily turnover produced by meals and defecation, superimposed over diet-related day-to-day variations.

Effects of scFOS on the composition of fecal microbiota and anxiety in patients with irritable bowel syndrome: a randomized, double blind, placebo controlled study.

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 (5 g d-1 ) 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.

Cognitive and hedonic responses to meal ingestion correlate with changes in circulating metabolites.

BACKGROUND: We have previously shown that meal ingestion induces cognitive perception (sensations) with a hedonic dimension (well-being) that depends on the characteristics of the meal and the appropriateness of the digestive response. The aim of the present study is to identify metabolomic biomarkers of the cognitive response to meal ingestion. METHODS: In 18 healthy subjects, the response to a test meal (Edanec, 1 kcal/mL) ingested until maximum satiation (50 mL/min) was assessed. Perception measurements and blood samples were taken before, at the end of the meal, and 20 min after ingestion. The cognitive response and the hedonic dimension were measured on 10 cm scales. Metabolomic analysis was performed using nuclear magnetic resonance (NMR) spectroscopy and values of triglycerides, insulin, peptide YY (PYY), and glucagon-like peptide-1 (GLP-1) were determined using conventional laboratory techniques. KEY RESULTS: Ingestion up to maximum satiation induced sensation of fullness and decreased digestive well-being. The total amount ingested by each subject correlated with the basal sensation of hunger, but not with other sensations or blood metabolite levels. Immediately after ingestion, satiation correlated with an increase in glucose (R = 0.49; p = 0.038) and valine levels (R = 0.48; p = 0.043). Twenty-minutes after finalizing ingestion, triglyceride levels had significantly increased which correlated with the recovery in well-being (R = 0.48; p = 0.046) and the decrease in desire to eat a food of choice (R = -0.56; p = 0.016). The increase in lipids inversely correlated with abdominal discomfort (R = -0.51; p = 0.032). CONCLUSIONS & INFERENCES: Cognitive and hedonic responses to meal ingestion correlate with changes in circulating metabolites, which may serve as objective biomarkers of perception.

Colonic content in health and its relation to functional gut symptoms.

BACKGROUND: Gut content may be determinant in the generation of digestive symptoms, particularly in patients with impaired gut function and hypersensitivity. Since the relation of intraluminal gas to symptoms is only partial, we hypothesized that non-gaseous component may play a decisive role. METHODS: Abdominal computed tomography scans were evaluated in healthy subjects during fasting and after a meal (n = 15) and in patients with functional gut disorders during basal conditions (when they were feeling well) and during an episode of abdominal distension (n = 15). Colonic content and distribution were measured by an original analysis program. KEY RESULTS: In healthy subjects both gaseous (87 ± 24 mL) and non-gaseous colonic content (714 ± 34 mL) were uniformly distributed along the colon. In the early postprandial period gas volume increased (by 46 ± 23 mL), but non-gaseous content did not, although a partial caudad displacement from the descending to the pelvic colon was observed. No differences in colonic content were detected between patients and healthy subjects. Symptoms were associated with discrete increments in gas volume. However, no consistent differences in non-gaseous content were detected in patients between asymptomatic periods and during episodes of abdominal distension. CONCLUSIONS & INFERENCES: In patients with functional gut disorders, abdominal distension is not related to changes in non-gaseous colonic content. Hence, other factors, such as intestinal hypersensitivity and poor tolerance of small increases in luminal gas may be involved.

Accumulative effect of food residues on intestinal gas production.

BACKGROUND: As mean transit time in the colon is longer than the interval between meals, several consecutive meal loads accumulate, and contribute to colonic biomass. Our aim was to determine the summation effect of fermentable food residues on intestinal gas production. METHODS: In eight healthy subjects, the volume of endogenous intestinal gas produced in the intestine over a 4-h period was measured by means of a wash-out technique, using an exogenous gas infusion into the jejunum (24 mL/min) and collection of the effluent via a rectal Foley catheter. The exogenous gas infused was labeled (5% SF6 ) to calculate the proportion of endogenous intestinal gas evacuated. In each subject, four experiments were performed ≥1 week apart combining a 1-day high- or low-flatulogenic diet with a test meal or fast. KEY RESULTS: Basal conditions: on the low-flatulogenic diet, intestinal gas production during fasting over the 4-h study period was 609 ± 63 mL. Effect of diet: during fasting, intestinal gas production on the high-flatulogenic diet was 370 ± 146 mL greater than on the low-flatulogenic diet (p = 0.040). Effect of test meal: on the low-flatulogenic diet, intestinal gas production after the test meal was 681 ± 114 mL greater than during fasting (p = 0.001); a similar effect was observed on the high-flatulogenic diet (599 ± 174 mL more intestinal gas production after the test meal than during fasting; p = 0.021). CONCLUSIONS & INFERENCES: Our data demonstrate temporal summation effects of food residues on intestinal gas production. Hence, intestinal gas production depends on pre-existing and on recent colonic loads of fermentable foodstuffs.

Intestinal gas content and distribution in health and in patients with functional gut symptoms.

BACKGROUND: The precise relation of intestinal gas to symptoms, particularly abdominal bloating and distension remains incompletely elucidated. Our aim was to define the normal values of intestinal gas volume and distribution and to identify abnormalities in relation to functional-type symptoms. METHODS: Abdominal computed tomography scans were evaluated in healthy subjects (n = 37) and in patients in three conditions: basal (when they were feeling well; n = 88), during an episode of abdominal distension (n = 82) and after a challenge diet (n = 24). Intestinal gas content and distribution were measured by an original analysis program. Identification of patients outside the normal range was performed by machine learning techniques (one-class classifier). Results are expressed as median (IQR) or mean ± SE, as appropriate. KEY RESULTS: In healthy subjects the gut contained 95 (71, 141) mL gas distributed along the entire lumen. No differences were detected between patients studied under asymptomatic basal conditions and healthy subjects. However, either during a spontaneous bloating episode or once challenged with a flatulogenic diet, luminal gas was found to be increased and/or abnormally distributed in about one-fourth of the patients. These patients detected outside the normal range by the classifier exhibited a significantly greater number of abnormal features than those within the normal range (3.7 ± 0.4 vs 0.4 ± 0.1; p < 0.001). CONCLUSIONS & INFERENCES: The analysis of a large cohort of subjects using original techniques provides unique and heretofore unavailable information on the volume and distribution of intestinal gas in normal conditions and in relation to functional gastrointestinal symptoms.

The Intestinal Gas Questionnaire: development of a new instrument for measuring gas-related symptoms and their impact on daily life.

BACKGROUND: Although gas-related symptoms (GRS) are common and intrusive, there are no questionnaires to quantitate this problem. This study aimed to develop an instrument to rectify this gap in our knowledge. METHODS: Concepts were initially identified from the literature and interviews with gastroenterologists. Exploratory one-to-one interviews and focus groups with irritable bowel syndrome (IBS) patients (n = 28) and non-IBS subjects (n = 27) with GRS were conducted in UK, France, and Spain leading to a conceptual framework for the questionnaire. Last, iterative rounds of cognitive debriefing were performed with IBS (n = 16) and non-IBS subjects (n = 14). KEY RESULTS: From the first three steps, nine GRS (bloating, distension, flatulence, odorous flatulence, difficult gas evacuation, stomach rumbling, belching, bad breath, and abdominal movement) were identified although abdominal movement was subsequently excluded. Twelve quality of life domains affected by these symptoms were identified as: Clothing, emotional, physical appearance, diet, daily living, work, social life, physical activity, relationships, sex life, sleep, and cognitive function. A 24-h recall for symptoms and a 7-day recall for impact assessment were supported by the qualitative findings. Cognitive debriefing confirmed the understanding of the instrument. Across the three languages, the instrument was conceptually and linguistically consistent. CONCLUSIONS & INFERENCES: The International Gas Questionnaire is a 2-part instrument, developed rigorously and simultaneously in three languages assessing seven symptoms (17 items) and their impact on 12 domains (26 items) in IBS and general population. It is now undergoing psychometric validation and should provide a unique tool for epidemiological surveys and clinical trials for developing new treatments for these symptoms.

[Prebiotics: concept, properties and beneficial effects]. / Prebiotics: concept, properties and beneficial effects.

Prebiotics are non-digestible food ingredients (oligosaccharides) that reach the colon and are used as substrate by microorganisms producing energy, metabolites and micronutrients used for the host; in addition they also stimulate the selective growth of certain beneficial species (mainly bifidobacteria and lactobacilli) in the intestinal microbiota. In this article, a multidisciplinary approach to understand the concept of prebiotic carbohydrates, their properties and beneficial effects in humans has been carried out. Definitions of prebiotics, reported by relevant international organizations and researchers, are described. A comprehensive description of accepted prebiotics having strong scientific evidence of their beneficial properties in humans (inulin-type fructans, FOS, GOS, lactulose and human milk oligosaccharides) is reported. Emerging prebiotics and those which are in the early stages of study have also included in this study. Taken into account that the chemical structure greatly influences carbohydrates prebiotic properties, the analytical techniques used for their analysis and characterization are discussed. In vitro and in vivo models used to evaluate the gastrointestinal digestion, absorption resistance and fermentability in the colon of prebiotics as well as major criteria to design robust intervention trials in humans are described. Finally, a comprehensive summary of the beneficial effects of prebiotics for health at systemic and intestinal levels is reported. The research effort on prebiotics has been intensive in last decades and has demonstrated that a multidisciplinary approach is necessary in order to claim their health benefits.

Los prebióticos son ingredientes alimentarios no digeribles (oligosacáridos) que llegan al colon y sirven de sustrato a los microorganismos, originando energía, metabolitos y micronutrientes utilizados por el hospedador y estimulando el crecimiento selectivo de determinadas especies beneficiosas (principalmente, bifidobacterias y lactobacilos) de la microbiota intestinal. En este artículo se realiza una revisión sobre los carbohidratos prebióticos desde diferentes perspectivas, comenzando por las definiciones de prebióticos formuladas a lo largo de los últimos treinta años por científicos y diferentes organismos internacionales. Se realiza una descripción detallada de los prebióticos aceptados, como tales, que presentan propiedades beneficiosas fundamentadas en estudios llevados a cabo en humanos (fructanos tipo inulina y FOS; GOS, lactulosa y oligosacáridos de leche humana), los que se consideran prebióticos emergentes y aquellos que se encuentran en fases iniciales de estudio. Además y teniendo en cuenta que la estructura química de los carbohidratos influye notablemente en sus propiedades prebióticas, se describen las técnicas más utilizadas para su análisis y caracterización. Asimismo, se detallan los modelos in vitro e in vivo más utilizados para estudiar la resistencia de los prebióticos a la digestión y la absorción gastrointestinal, la fermentación de los prebióticos en el colon así como los criterios a tener en cuenta para llevar a cabo ensayos de intervención en humanos. Por último se realiza una amplia descripción de los efectos beneficiosos de los prebióticos para la salud a nivel intestinal y sistémico. Como conclusión, podría decirse que la investigación existente hasta el momento, sobre prebióticos, es extensa y pone de manifiesto que es necesario considerar un gran número de factores para poder atribuir alegaciones de salud a un prebiótico.

Prebióticos; concepto, propiedades y efectos beneficiosos / Prebiotics: concept, properties and beneficial effects

Los prebióticos son ingredientes alimentarios no digeribles (oligosacáridos) que llegan al colon y sirven de sustrato a los microorganismos, originando energía, metabolitos y micronutrientes utilizados por el hospedador y estimulando el crecimiento selectivo de determinadas especies beneficiosas (principalmente, bifidobacterias y lactobacilos) de la microbiota intestinal. En este artículo se realiza una revisión sobre los carbohidratos prebió- ticos desde diferentes perspectivas, comenzando por las definiciones de prebióticos formuladas a lo largo de los últimos treinta años por científicos y diferentes organismos internacionales. Se realiza una descripción detallada de los prebióticos aceptados, como tales, que presentan propiedades beneficiosas fundamentadas en estudios llevados a cabo en humanos (fructanos tipo inulina y FOS; GOS, lactulosa y oligosacáridos de leche humana), los que se consideran prebióticos emergentes y aquellos que se encuentran en fases iniciales de estudio. Además y teniendo en cuenta que la estructura química de los carbohidratos influye notablemente en sus propiedades prebióticas, se describen las técnicas más utilizadas para su análisis y caracterización. Asimismo, se detallan los modelos in vitro e in vivo más utilizados para estudiar la resistencia de los prebióticos a la digestión y la absorción gastrointestinal, la fermentación de los prebióticos en el colon así como los criterios a tener en cuenta para llevar a cabo ensayos de intervención en humanos. Por último se realiza una amplia descripción de los efectos beneficiosos de los prebióticos para la salud a nivel intestinal y sistémico. Como conclusión, podría decirse que la investigación existente hasta el momento, sobre prebióticos, es extensa y pone de manifiesto que es necesario considerar un gran número de factores para poder atribuir alegaciones de salud a un prebiótico (AU)

Prebiotics are non-digestible food ingredients (oligosaccharides) that reach the colon and are used as substrate by microorganisms producing energy, metabolites and micronutrients used for the host; in addition they also stimulate the selective growth of certain beneficial species (mainly bifidobacteria and lactobacilli) in the intestinal microbiota. In this article, a multidisciplinary approach to understand the concept of prebiotic carbohydrates, their properties and beneficial effects in humans has been carried out. Definitions of prebiotics, reported by relevant international organizations and researchers, are described. A comprehensive description of accepted prebiotics having strong scientific evidence of their beneficial properties in humans (inulin-type fructans, FOS, GOS, lactulose and human milk oligosaccharides) is reported. Emerging prebiotics and those which are in the early stages of study have also included in this study. Taken into account that the chemical structure greatly influences carbohydrates prebiotic properties, the analytical techniques used for their analysis and characterization are discussed. In vitro and in vivo models used to evaluate the gastrointestinal digestion, absorption resistance and fermentability in the colon of prebiotics as well as major criteria to design robust intervention trials in humans are described. Finally, a comprehensive summary of the beneficial effects of prebiotics for health at systemic and intestinal levels is reported. The research effort on prebiotics has been intensive in last decades and has demonstrated that a multidisciplinary approach is necessary in order to claim their health benefits (AU)