Gastrointestinal Contributions to the Postprandial Experience

Foodingestion induces homeostatic sensations (satiety, fullness) with a hedonic dimension (satisfaction, changes in mood) that characterize the postprandial experience. Both types of sensation are secondary to intraluminal stimuli produced by the food itself, as well as to the activity of the digestive tract. Postprandial sensations also depend on the nutrient composition of the meal and on colonic fermentation of non-absorbed residues. Gastrointestinal function and the sensitivity of the digestive tract, i.e., perception of gut stimuli, are determined by inherent individual factors, e.g., sex, and can be modulated by different conditioning mechanisms. This narrative review examines the factors that determine perception of digestive stimuli and the postprandial experience

Un desdejuni calòric disminueix la satisfacció después d'esmorzar a mig matí

Un estudi del Departament de Medicina de la UAB i l'Hospital Universitari Vall d'Hebron ha analitzat l'efecte de la quantitat de calories ingerides durant el desdejuni, a primera hora del matí, a la satisfacció i sensació de benestar en prendre un petit esmorzar dues hores després. Com més calòric és el primer àpat, menys es gaudeix del segon.Un estudio del Departamento de Medicina de la UAB y el Hospital Universitario Vall d'Hebron ha analizado el efecto de la cantidad de calorías ingeridas durante el desayuno en la satisfacción y sensación de bienestar al tomar un pequeño almuerzo dos horas después. Cuanto más calórico es el desayuno, menos se disfruta del almuerzo.A study conducted by the UAB Department of Medicine and the Vall d'Hebron University Hospital analyses the effects a high-calorie breakfast early in the morning has on the satifaction and sense of well-being after eating a mid-morning snack two hours later. More breakfast calories results in less enjoyment when eating the snack

Conditioning by a Previous Experience Impairs the Rewarding Value of a Comfort Meal

Pavlovian conditioning; Digestive well-being; Eating behaviourCondicionamiento pavloviano; Bienestar digestivo; Conducta alimentariaCondicionament pavlovià; Benestar digestiu; Conducta alimentàriaBackground. Meal ingestion induces a postprandial experience that involves homeostatic and hedonic sensations. Our aim was to determine the effect of aversive conditioning on the postprandial reward of a comfort meal. Methods: A sham-controlled, randomised, parallel, single-blind study was performed on 12 healthy women (6 per group). A comfort meal was tested before and after coupling the meal with an aversive sensation (conditioning intervention), induced by infusion of lipids via a thin naso-duodenal catheter; in the pre- and post-conditioning tests and in the control group, a sham infusion was performed. Participants were instructed that two recipes of a tasty humus would be tested; however, the same meal was administered with a colour additive in the conditioning and post-conditioning tests. Digestive well-being (primary outcome) was measured every 10 min before and 60 min after ingestion using graded scales. Results: In the aversive conditioning group, the comfort meal in the pre-conditioning test induced a pleasant postprandial experience, which was significantly lower in the post-conditioning test; the effect of aversive conditioning (change from pre- to post-conditioning) was significant as compared to sham conditioning in the control group, which showed no differences between study days. Conclusion: The hedonic postprandial response to a comfort meal in healthy women is impaired by aversive conditioning. ClinicalTrials.gov ID: NCT04938934.The present study was supported in part by the Ministerio de Ciencia e Innovación (Agencia Estatal de Investigación, PID2021-122295OB-I00). Ciberehd is funded by the Instituto de Salud Carlos III. D.M.L received support from the Israeli Medical Association and from the Israel Gastroenterological Association

Reversal of Conditioned Food Aversion Using a Cognitive Intervention : A Sham-Controlled, Randomized, Parallel Study

Background: Aversive conditioning weakens the gratifying value of a comfort meal. The aim was to determine the effect of a cognitive intervention to reverse aversive conditioning and restore hedonic postprandial response. Methods: This was a randomized, sham-controlled, single-blind, parallel study that was conducted on 12 healthy women (n = 6 in each group). The reward value of a comfort meal was measured on different days: at initial exposure, after aversive conditioning (administration of the same meal with a masked fat overload on the previous day) and after a cognitive intervention (disclosing the aversive conditioning paradigm in the test group vs. no explanation in the control group). The primary outcome, digestive wellbeing, was determined using graded scales at regular intervals before and after ingestion. Results: At initial exposure, the comfort meal produced a rewarding experience that was impaired using aversive conditioning; upon re-exposure to the original meal, the cognitive intervention increased meal wanting and liking; improved digestive wellbeing and mood; tended to reduce postprandial satiety, bloating/fullness; and abolished discomfort/pain, thereby restoring the hedonic value of the comfort meal. By contrast, sham intervention had no effects, and the postprandial sensations remained like the responses to the offending meal. Conclusion: In this proof-of-concept study, we demonstrate that in healthy women, a mild, short-term acquired aversion to a comfort meal can be reversed using a cognitive intervention

Metabolic response of intestinal microbiota to guar gum consumption

BackgroundGuar gum is used extensively as a thickening agent in food, but it remains uncertain whether and to what extent it is fermented by colonic microbiota and whether it has microbiota modulatory properties.AimTo determine the metabolic response of intestinal microbiota to guar gum consumption, specifically, the extent of initial fermentation and subsequent adaptation.MethodsSingle-center, single arm, open label, proof-of-concept study testing the effect of guar gum on microbiota metabolism and adaptation. Healthy male subjects (n = 12) were administered gum guar (8 g/day) for 18 days. Outcomes were measured before, at initial and late administration: (a) anal gas evacuations (number/day); (b) digestive sensations (daily scales); and (c) fecal gut microbiota taxonomy and metabolic functions by shotgun sequencing.ResultsAt initial consumption, guar gum induced a transient increase in anal gas evacuations and digestive sensations; gas evacuation completely reverted upon continuous administration, whereas sensations reverted only in part. Guar gum induced moderate changes in human microbiota composition at both taxonomic and functional levels. Positive associations between effects on microbiota (proliferation of Agathobaculum butyriciproducens and Lachnospira pectinoschiza) and hedonic sensations were detected.ConclusionGuar gum is metabolized by intestinal microbiota, and, upon continuous consumption, induces a selective adaptation of microbial taxonomy and function. These data highlight the potential interest of guar gum for novel prebiotic ingredient formulation

Ideen un mètode per evitar la regurgitació recurrent

La ruminació, la tornada del menjar cap a la boca després de ser ingerida, pot ser un problema menor o dur a complicacions nutricionals severes. L'equip del professor del Departament de Medicina de la UAB i investigador de l'Institut de Recerca Hospital Universitari Vall d'Hebron Fernando Azpiroz ha desenvolupat un mètode per ensenyar a qui la pateix a modular l'activitat muscular fins a suprimir aquest comportament.La rumiación, la vuelta de la comida hacia la boca después de ser ingerida, puede ser un problema menor o llevar a complicaciones nutricionales severas. El equipo del profesor del Departamento de Medicina de la UAB e investigador del Instituto de Investigación Hospital Universitario Vall d'Hebron Fernando Azpiroz ha desarrollado un método para enseñar a quienes la padecen a modular la actividad muscular hasta suprimir este comportamiento.Rumination, the regurgitation of recently ingested food into the mouth, can be a minor problem or lead to severe nutritional complications. Professor Fernando Azpiroz, from the UAB Department of Medicine and Vall d'Hebron Research Institute, and his team, have developed a new method to show people suffering from rumination how to modulate their muscular activity in order to suppress it

Metabolic response of intestinal microbiota to guar gum consumption

Food additive; Guar gum; PrebioticAdditiu alimentari; Goma guar; PrebiòticAditivo alimentario; Goma guar; PrebióticoBackground: Guar gum is used extensively as a thickening agent in food, but it remains uncertain whether and to what extent it is fermented by colonic microbiota and whether it has microbiota modulatory properties. Aim: To determine the metabolic response of intestinal microbiota to guar gum consumption, specifically, the extent of initial fermentation and subsequent adaptation. Methods: Single-center, single arm, open label, proof-of-concept study testing the effect of guar gum on microbiota metabolism and adaptation. Healthy male subjects (n = 12) were administered gum guar (8 g/day) for 18 days. Outcomes were measured before, at initial and late administration: (a) anal gas evacuations (number/day); (b) digestive sensations (daily scales); and (c) fecal gut microbiota taxonomy and metabolic functions by shotgun sequencing. Results: At initial consumption, guar gum induced a transient increase in anal gas evacuations and digestive sensations; gas evacuation completely reverted upon continuous administration, whereas sensations reverted only in part. Guar gum induced moderate changes in human microbiota composition at both taxonomic and functional levels. Positive associations between effects on microbiota (proliferation of Agathobaculum butyriciproducens and Lachnospira pectinoschiza) and hedonic sensations were detected. Conclusion: Guar gum is metabolized by intestinal microbiota, and, upon continuous consumption, induces a selective adaptation of microbial taxonomy and function. These data highlight the potential interest of guar gum for novel prebiotic ingredient formulation.This work was supported in part by the projects PID2021-122295OB-I00 (Ministerio de Ciencia e Innovación, Spain). Ciberehd is funded by the Instituto de Salud Carlos III

Understanding the large shift photocurrent of WS2_{2} nanotubes: A comparative analysis with monolayers

We study the similarities and differences in the shift photocurrent contribution to the bulk photovoltaic effect between transition-metal dichalcogenide monolayers and nanotubes. Our analysis is based on density functional theory in combination with the Wannier interpolation technique for the calculation of the shift photoconductivity tensor. Our results show that for nanotube radii of practical interest $r>60$~\AA, the shift photoconductivity of a single-wall nanotube is well described by that of the monolayer. Additionally, we quantify the shift photocurrent generated under realistic experimental conditions like device geometry and absorption capabilities. We show that a typical nanotube can generate a photocurrent of around 10 nA, while the monolayer only attains a maximum of 1 nA. This enhancement is mainly due to the larger conducting cross section of a nanotube in comparison to a monolayer. Finally, we discuss our results in the context of recent experimental measurements on WS$_{2}$ monolayer and nanotubes[Zhang et al., Nature 570, 349 (2019)].Comment: 11 pages, 9 figure