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

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

Effect of colonic distension on small bowel motility measured by jejunal high-resolution manometry

Colonic distension; High-resolution manometry; Small bowel motilityDistensió colònica; Manometria d'alta resolució; Motilitat de l'intestí primDistensión colónica; Manometría de alta resolución; Motilidad del intestino delgadoBackground Abnormal motility patterns in the jejunum can be detected in patients with prominent colonic content, and these abnormalities may be due to either a primary jejunal dysfunction or a reflex distortion. The objective of the present study was to determine the effect of colonic distension on small bowel postprandial motility using high-resolution manometry. Methods Single center, controlled, parallel, randomized, single blind study in healthy subjects testing the effect of colonic filling vs sham infusion on the responses to a meal in 16 healthy subjects. Nutrients were continuously infused in the proximal jejunum (2 Kcal/min) during the 2-h study period to induce a steady-state postprandial motor pattern. Jejunal motility was measured by water-perfused, high-resolution manometry. After 1 h postprandial recording (basal period), gas was infused during 7.5 min via a rectal tube (720 mL or sham infusion), and jejunal motility was recorded for another hour. Key Results Jejunal postprandial motility during the basal period was characterized by two overlapping components: a) continuous segmental activity (non-propagated or shortly propagated) and b) intercurrent propagated fronts (3.8 ± 1.1 fronts of 2-5 clustered contractions/h >10 cm propagation). As compared to sham infusion, colonic gas filling: a) inhibited continuous segmental contractile activity (by 17 ± 4%; p = 0.044 vs control group) and b) stimulated intermittent propagated fronts (up to 9.0 ± 2.2 fronts/h; p = 0.017 vs control group). Conclusions and Inferences Long retrograde reflexes induced by colonic distension distort the balance between segmental and propagated activity, and may affect the normal response of the jejunum to food ingestion. Jejunal manometry in patients may be artifacted by colonic overload

Evaluation of abdominal gas by plain abdominal radiographs

Abdominal CT imaging; Abdominal distension; Intestinal gasTAC abdominal; Distensión abdominal; Gas intestinalTAC abdominal; Distensió abdominal; Gas intestinalBackground Our aim was to determine the reliability of plain abdominal radiographs for the evaluation of abdominal gas content in patients with functional digestive symptoms. Methods Abdominal CT scan scout views, mimicking a conventional plain abdominal radiograph, were obtained from 30 patients both during episodes of abdominal distension and basal conditions. Physicians (n = 50) were instructed to rate the estimated volume of gas in the 60 images presented in random sequence using a scale graded from 0 to ≥600 ml. Key Results The gas volumes estimated in the scout views differed from those measured by CT by a median of 90 (95% CI 70–102) ml, and the misestimation was not related to the absolute volume in the image. The accuracy of the observers, measured by their mean misestimation, was not related to their specialty or the training status (misestimation by 96 (95% CI 85–104) ml in staff vs 78 (70–106) ml in residents; p = 0.297). The accuracy was independent of the order of presentation of the images. Gas volume measured by CT in the images obtained during episodes of abdominal distension differed by a median of 39 (95% CI 29–66) ml from those during basal conditions, and this difference was misestimated by a median of 107 (95% CI 94–119) ml. The accuracy of these estimations was not related to the absolute gas volumes (R = −0.352; p < 0.001) or the magnitude of the differences. Conclusions & Inferences Plain abdominal radiographs have limited value for the evaluation of abdominal gas volume in patients with functional gut disorders.This work was supported in part by the Spanish Ministry of Economy and Competitiveness (Dirección General de Investigación Científica y Técnica, grant SAF 2016-76,648-R to F Azpiroz); Ciberehd is funded by the Instituto de Salud Carlos III. Dan M. Livovsky received support from the Israeli Medical Association and from Israeli Gastroenterological Association 2020 fellowship grants

Evaluation of abdominal gas by plain abdominal radiographs

Our aim was to determine the reliability of plain abdominal radiographs for the evaluation of abdominal gas content in patients with functional digestive symptoms. Abdominal CT scan scout views, mimicking a conventional plain abdominal radiograph, were obtained from 30 patients both during episodes of abdominal distension and basal conditions. Physicians (n = 50) were instructed to rate the estimated volume of gas in the 60 images presented in random sequence using a scale graded from 0 to ≥600 ml. The gas volumes estimated in the scout views differed from those measured by CT by a median of 90 (95% CI 70-102) ml, and the misestimation was not related to the absolute volume in the image. The accuracy of the observers, measured by their mean misestimation, was not related to their specialty or the training status (misestimation by 96 (95% CI 85-104) ml in staff vs 78 (70-106) ml in residents; p = 0.297). The accuracy was independent of the order of presentation of the images. Gas volume measured by CT in the images obtained during episodes of abdominal distension differed by a median of 39 (95% CI 29-66) ml from those during basal conditions, and this difference was misestimated by a median of 107 (95% CI 94-119) ml. The accuracy of these estimations was not related to the absolute gas volumes (R = −0.352; p < 0.001) or the magnitude of the differences. Plain abdominal radiographs have limited value for the evaluation of abdominal gas volume in patients with functional gut disorders. Example of three-dimensional reconstruction of abdominal CT scan showing intestinal gas. Plain AP projection (scout view) of the same scan. Relation between objective values of intestinal gas, measured by a validated CT technique in patients with functional gut disorders, and the subjective estimation of gas volumes on plain AP projection of the same CT scans (scout views) by 48 physicians. Individual estimations of 60 images are shown. CONCLUSION: The volumes of abdominal gas were grossly misestimated in the scout views, indicating that plain abdominal radiographs have no value for the evaluation of intestinal gas volume in patients with functional gut disorders

Abdominothoracic Postural Tone Influences the Sensations Induced by Meal Ingestion

Postprandial objective abdominal distention is frequently associated with a subjective sensation of abdominal bloating, but the relation between both complaints is unknown. While the bloating sensation has a visceral origin, abdominal distention is a behavioral somatic response, involving contraction and descent of the diaphragm with protrusion of the anterior abdominal wall. Our aim was to determine whether abdominal distention influences digestive sensations. In 16 healthy women we investigated the effect of intentional abdominal distention on experimentally induced bloating sensation (by a meal overload). Participants were first taught to produce diaphragmatic contraction and visible abdominal distention. After a meal overload, sensations of bloating (0 to 10) and digestive well-being (−5 to + 5) were measured during 30-s. maneuvers alternating diaphragmatic contraction and diaphragmatic relaxation. Compared to diaphragmatic relaxation, diaphragmatic contraction was associated with diaphragmatic descent (by 21 + 3 mm; p &lt; 0.001), objective abdominal distension (32 + 5 mm girth increase; p = 0.001), more intense sensation of bloating (7.3 + 0.4 vs. 8.0 + 0.4 score; p = 0.010) and lower digestive well-being (−0.9 + 0.5 vs. −1.9 + 0.5 score; p = 0.028). These results indicate that somatic postural tone underlying abdominal distention worsens the perception of visceral sensations (ClinicalTrials.gov ID: NCT04691882)

Food, Eating, and the Gastrointestinal Tract

Food ingestion induces a metered response of the digestive system. Initially, the upper digestive system reacts to process and extract meal substrates. Later, meal residues not absorbed in the small bowel, pass into the colon and activate the metabolism of resident microbiota. Food consumption also induces sensations that arise before ingestion (e.g., anticipatory reward), during ingestion (e.g., gustation), and most importantly, after the meal (i.e., the postprandial experience). The postprandial experience involves homeostatic sensations (satiety, fullness) with a hedonic dimension (digestive well-being, mood). The factors that determine the postprandial experience are poorly understood, despite their potential role in personalized diets and healthy eating habits. Current data suggest that the characteristics of the meal (amount, palatability, composition), the activity of the digestive system (suited processing), and the receptivity of the eater (influenced by multiple conditioning factors) may be important in this context

Construction of complicated multifactor models of optimal form on the basis of statistical data, when the physical essence of phenomenon is known

The work contains computer-aided method of construction of multifactor and complicated models on the basis of experimental data. The models are non-linear but traditional (constructed with the help of the method with the preliminary transformation of the matrix of the initial data and the subsequent reverse transformation of the results). The models can have different form linear, multiplicative, exponent and so on. After the construction the models are improved using method of Givis and Hook, which improves their statistical characteristics and the quality of representation of the results of experiment. This work is in a certain way methodological. We have shown in it that having enough experimental data we can improve the quality of the models and formulas even those which already exist in school textbooks. On the other hand it is shown here that when knowing the essence of the phenomenon it is possible to choose an optimal model from the multitude of regressional models

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. ClinicalTrials.gov ID: NCT05897411