Digestive, cognitive and hedonic responses to a meal

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

BACKGROUND

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.

Effect of Resistant Dextrin on Intestinal Gas Homeostasis and Microbiota

Previous studies have shown that a resistant dextrin soluble fibre has prebiotic properties with related health benefits on blood glucose management and satiety. Our aim was to demonstrate the effects of continuous administration of resistant dextrin on intestinal gas production, digestive sensations, and gut microbiota metabolism and composition. Healthy subjects (n = 20) were given resistant dextrin (14 g/d NUTRIOSE^®, Roquette Frères, Lestrem, France) for four weeks. Outcomes were measured before, at the beginning, end, and two weeks after administration: anal evacuations of gas during daytime; digestive perception, girth, and gas production in response to a standard meal; sensory and digestive responses to a comfort meal; volume of colonic biomass by magnetic resonance; taxonomy and metabolic functions of fecal microbiota by shotgun sequencing; metabolomics in urine. Dextrin administration produced an initial increase in intestinal gas production and gas-related sensations, followed by a subsequent decrease, which magnified after discontinuation. Dextrin enlarged the volume of colonic biomass, inducing changes in microbial metabolism and composition with an increase in short chain fatty acids-producing species and modulation of bile acids and biotin metabolism. These data indicate that consumption of a soluble fibre induces an adaptative response of gut microbiota towards fermentative pathways with lower gas production.

Differential Effects of Western and Mediterranean-Type Diets on Gut Microbiota: A Metagenomics and Metabolomics Approach

Our aim was to determine the effect of diet on gut microbiota, digestive function and sensations, using an integrated clinical, metagenomics and metabolomics approach. We conducted a cross-over, randomised study on the effects of a Western-type diet versus a fibre-enriched Mediterranean diet. In 20 healthy men, each diet was administered for 2 weeks preceded by a 2-week washout diet. The following outcomes were recorded: (a) number of anal gas evacuations; (b) digestive sensations; (c) volume of gas evacuated after a probe meal; (d) colonic content by magnetic resonance imaging; (e) gut microbiota taxonomy and metabolic functions by shotgun sequencing of faecal samples; (f) urinary metabolites using untargeted metabolomics. As compared to a Western diet, the Mediterranean diet was associated with (i) higher number of anal gas evacuations, (ii) sensation of flatulence and borborygmi, (iii) larger volume of gas after the meal and (iv) larger colonic content. Despite the relatively little difference in microbiota composition between both diets, microbial metabolism differed substantially, as shown by urinary metabolite profiles and the abundance of microbial metabolic pathways. The effects of the diet were less evident in individuals with robust microbiotas (higher beta-diversity). To conclude, healthy individuals tolerate dietary changes with minor microbial modifications at the composition level but with remarkable variation in microbial metabolism.

Gastrointestinal Contributions to the Postprandial Experience

Food ingestion 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.

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 < 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.

Biological Response to Meal Ingestion: Gender Differences

In a previous study, we demonstrated that women enjoyed and tolerated lower meal loads than men. Hence, we hypothesized that with the same meal load, their postprandial response is more pronounced than in men. We performed a randomized parallel trial in 12 women and 12 men comparing the postprandial responses to a palatable comfort meal. We measured homeostatic sensations (hunger/satiety, fullness) and hedonic sensations (digestive well-being, mood) on 10 cm scales, vagal tone by heart ratio variability and the metabolomic profile before and after meal ingestion. Gender differences were analyzed by repeated measures ANCOVA. Overall (n = 24), ingestion of the probe meal induced satiation, fullness, digestive well-being and improved mood (main time-effect p ≤ 0.005 for all). Women exhibited a more intense sensory experience, specially more postprandial fullness, than men [main gender-effect F (1, 21) = 7.14; p = 0.014]; hedonic responses in women also tended to be stronger than in men. Women exhibited more pronounced effects on vagal tone [main gender-effect F (1, 21) = 5.5; p = 0.029] and a different lipoprotein response than men. In conclusion, our data indicate that gender influences the responses to meal ingestion, and these differences may explain the predisposition and higher incidence in women of meal-related functional disorders.

Meal Enjoyment and Tolerance in Women and Men

Various conditioning factors influence the sensory response to a meal (inducible factors). We hypothesized that inherent characteristics of the eater (constitutive factors) also play a role. The aim of this proof-of-concept study was to determine the role of gender, as an individual constitutive factor, on the meal-related experience. Randomized parallel trial in 10 women and 10 men, comparing the sensations before, during, and after stepwise ingestion of a comfort meal up to full satiation. Comparisons were performed by repeated Analysis of Covariance (ANCOVA) measures. During stepwise ingestion, satisfaction initially increased up to a peak, and later decreased down to a nadir at the point of full satiation. Interestingly, the amount of food consumed at the well-being peak was lower, and induced significantly less fullness in women than in men. Hence, men required a larger meal load and stronger homeostatic sensations to achieve satisfaction. The same pattern was observed at the level of full satiation: men ate more and still experienced positive well-being, whereas in women, well-being scores dropped below pre-meal level. The effect of gender on the ingestion experience suggests that other constitutive factors of the eater may also influence responses to meals.

Metabolomic signature of the postprandial experience

BACKGROUND

Ingestion of a meal up to maximal tolerance induces unpleasant fullness sensation and changes in circulating metabolites. Our aim was to evaluate the relation between postprandial sensations and the metabolomic responses to a comfort meal.

METHODS

In 32 non-obese healthy men, homeostatic sensations (hunger/satiety, fullness), hedonic sensations (digestive well-being, mood), and the metabolomic profile in plasma (low-molecular weight metabolites and lipoprotein profiles) were measured before and 20 minutes after a comfort meal (warm ham and cheese sandwich and juice; total 300 mL; 425 kcal). Perception was measured on 10 cm scales and the metabolomic response by nuclear magnetic resonance spectroscopy.

KEY RESULTS

The comfort meal induced homeostatic sensations (satiety and fullness) associated with a positive hedonic reward (enhanced digestive well-being and mood) and a clear change in the metabolomic profile with a sharp discrimination between the pre and postprandial state by a non-supervised principal component analysis. The change in circulating metabolites correlated with the postprandial sensations: the increase in alanine correlated with the increase in fullness (R = 0.50; P = 0.004) and well-being (R = 0.50; P = 0.004); the increase in glucose correlated with the sensation of fullness (R = 0.40; P = 0.023) and enhanced mood (R = 0.41; P = 0.020).

CONCLUSION AND INFERENCES

Metabolomic changes in the response to a meal may provide an objective index of the postprandial experience, which may have clinical implications in the management of patients with poor 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.

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.

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.

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.

Effect of Chicory-derived Inulin on Abdominal Sensations and Bowel Motor Function

GOAL

To determine the effect of a prebiotic chicory-derived inulin-type fructan on the tolerance of intestinal gas.

BACKGROUND

Subjects with gas-related complaints exhibit impaired handling of intestinal gas loads and we hypothesized that inulin would have a beneficial effect.

STUDY

Placebo-controlled, parallel, randomized, double-blind trial. Subjects with abdominal symptoms and reduced tolerance of intestinal gas (selected by a pretest) received either inulin (8 g/d, n=18) or maltodextrin as a placebo (8 g/d, n=18) for 4 weeks. A gas challenge test (4 h jejunal gas infusion at 12 mL/min while measuring abdominal symptoms and gas retention for 3 h) was performed before and at the end of the intervention phase. Gastrointestinal symptoms and bowel habits (using daily questionnaires for 1 wk) and fecal bifidobacteria counts were measured before and at the end of the intervention.

RESULTS

Inulin decreased gas retention during the gas challenge test (by 22%; P=0.035 vs. baseline), while the placebo did not, but the intergroup difference was not statistically significant (P=0.343). Inulin and placebo reduced the perception of abdominal sensations in the gas challenge test to a similar extent (by 52% and 43%, respectively). Participants reported moderate gastrointestinal symptoms and normal bowel habits during baseline examination, and these findings remained unchanged in both groups during the intervention. Inulin led to a higher relative abundance of bifidobacteria counts (P=0.01 vs. placebo).

CONCLUSIONS

A daily dose of inulin that promotes bifidobacteria growth and may improve gut function, is well tolerated by subjects with gastrointestinal complaints.

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.

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.

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.

Ghrelin, CCK, GLP-1, and PYY(3-36): Secretory Controls and Physiological Roles in Eating and Glycemia in Health, Obesity, and After RYGB

The efficacy of Roux-en-Y gastric-bypass (RYGB) and other bariatric surgeries in the management of obesity and type 2 diabetes mellitus and novel developments in gastrointestinal (GI) endocrinology have renewed interest in the roles of GI hormones in the control of eating, meal-related glycemia, and obesity. Here we review the nutrient-sensing mechanisms that control the secretion of four of these hormones, ghrelin, cholecystokinin (CCK), glucagon-like peptide-1 (GLP-1), and peptide tyrosine tyrosine [PYY(3-36)], and their contributions to the controls of GI motor function, food intake, and meal-related increases in glycemia in healthy-weight and obese persons, as well as in RYGB patients. Their physiological roles as classical endocrine and as locally acting signals are discussed. Gastric emptying, the detection of specific digestive products by small intestinal enteroendocrine cells, and synergistic interactions among different GI loci all contribute to the secretion of ghrelin, CCK, GLP-1, and PYY(3-36). While CCK has been fully established as an endogenous endocrine control of eating in healthy-weight persons, the roles of all four hormones in eating in obese persons and following RYGB are uncertain. Similarly, only GLP-1 clearly contributes to the endocrine control of meal-related glycemia. It is likely that local signaling is involved in these hormones' actions, but methods to determine the physiological status of local signaling effects are lacking. Further research and fresh approaches are required to better understand ghrelin, CCK, GLP-1, and PYY(3-36) physiology; their roles in obesity and bariatric surgery; and their therapeutic potentials.

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.