Oral and Gastrointestinal Sensing of Dietary Fat and Appetite Regulation in Humans: Modification by Diet and Obesity

Dietary fat interacts with receptors in both the oral cavity and the gastrointestinal (GI) tract to regulate fat and energy intake. This review discusses recent developments in our understanding of the mechanisms underlying the effects of fat, through its digestive products, fatty acids (FAs), on GI function and energy intake, the role of oral and intestinal FA receptors, and the implications that changes in oral and small intestinal sensitivity in response to ingested fat may have for the development of obesity

Effects of lipase inhibition on gastric emptying and alcohol absorption in healthy subjects

The rate of alcohol absorption is dependent on gastric emptying (GE). As the slowing of GE by fat is dependent on lipolysis, orlistat may increase the rise in blood alcohol when alcohol is consumed with, or after, fat. The aim of the study was to evaluate the effects of orlistat on GE and blood alcohol after an alcohol-containing drink following a fat ‘preload’, in healthy subjects. Ten healthy males consumed 120 ml cream with or without 120 mg orlistat, 30 min before an alcohol-containing drink labelled with 20 MBq [99 mTc]sulfur colloid on 2 d. GE, plasma alcohol and blood glucose were measured. GE was slightly faster with orlistat (P<0·05) compared with control. Plasma alcohol at 15 min was slightly higher with orlistat (0·034 (sem 0·006) g/100 ml) v. control (0·029 (sem 0·005) g/100 ml) (P<0·05), but there was no effect on the area under the curve 0–240 min. The increase in blood glucose was greater with orlistat, for example, at 15 min (1·07 (sem 0·2) mmol/l) v. control (0·75 (sem 0·2) mmol/l) (P=0·05). The rise in blood glucose and plasma alcohol were related (for example, at 15 min r 0·49; P=0·03). In conclusion, lipase inhibition accelerates GE of an alcohol-containing drink following a fat ‘preload’ with a minor increase in the initial rise in plasma alcohol.Reawika Chaikomin, Antonietta Russo, Christopher K. Rayner, Christine Feinle-Bisset, Deirdre G. O’Donovan, Michael Horowitz and Karen L. Jone

Upper Gastrointestinal Function in Morbidly Obese Adolescents before and Six Months after Gastric Banding

“This is a pre-print of an article published in Obesity Surgery. The final authenticated version is available online at: https://doi.org/10.1007/s11695-017-3000-3”. © Springer Science+Business Media, LLC 2017 This author accepted manuscript is made available following 12 month embargo from date of publication (Nov 2017) in accordance with the publisher’s archiving policyBackground The effects of laparoscopic adjustable gastric band (LAGB) placement on upper gastrointestinal tract function in obese adolescents are unknown. Therefore, our aim was to determine the short-term effects of LAGB on esophageal motility, gastroesophageal reflux, gastric emptying, appetite-regulatory hormones, and perceptions of post-prandial hunger and fullness. Methods This study was part of a prospective cohort study (March 2009–December 2015) in one tertiary referral hospital. The study included obese adolescents (14–18 years) with a body mass index (BMI) > 40 (or ≥ 35 with comorbidities). Gastric emptying was assessed by 13C-octanoic acid breath test, pharyngeal, and esophageal motor function by high-resolution manometry with impedance (HRIM), and appetite and other perceptions using 100-mm visual analogue scales. Dysphagia symptoms were scored using a Dakkak questionnaire. Data were compared pre- and post-LAGB placement and at a 6-month follow-up. Results Based upon analysis of 15 adolescents, at the 6-month follow-up, LAGB placement: (i) led to a significant reduction in weight and BMI; (ii) increased fullness and decreased hunger post-meal; (iii) increased symptoms of dysphagia after solid food; and, despite these effects, (iv) caused little or no changes to appetite hormones, while (v) effects on gastric emptying, esophageal motility, esophageal bolus transport, and esophageal emptying were not significant. Conclusion In adolescents, LAGB improved BMI and altered the sensitivity to nutrients without significant effects on upper gastrointestinal tract physiology at the 6-month follow-up

Pooled-data analysis identifies pyloric pressures and plasma cholecystokinin concentrations as major determinants of acute energy intake in healthy, lean men

Background: The interaction of nutrients with the small intestine modulates gastropyloroduodenal motility, stimulates the release of gut hormones, and suppresses appetite and energy intake. Objective: We evaluated which, if any, of these variables are independent determinants of acute energy intake in healthy, lean men. Design: We pooled data from 8 published studies that involved a total of 67 healthy, lean men in whom antropyloroduodenal pressures, gastrointestinal hormones, and perceptions were measured during intraduodenal nutrient or intravenous hormone infusions. In all of the studies, the energy intake at a buffet lunch was quantified immediately after the infusions. To select specific motor, hormone, or perception variables for inclusion in a multivariable mixed-effects model for determination of independent predictors of energy intake, we assessed all variables for collinearity and determined within-subject correlations between energy intake and these variables by using bivariate analyses adjusted for repeated measures. Results: Although correlations were shown between energy intake and antropyloroduodenal pressures, plasma hormone concentrations, and gastrointestinal perceptions, only the peak number of isolated pyloric-pressure waves, peak plasma cholecystokinin concentration, and area under the curve of nausea were identified as independent predictors of energy intake (all P < 0.05), so that increases of 1 pressure wave, 1 pmol/L, and 1 mm · min were associated with reductions in energy intake of 36, 88, and 0.4, respectively. Conclusion: We identified specific changes in gastrointestinal motor and hormone functions (ie, stimulation of pyloric pressures and plasma cholecystokinin) and nausea that are associated with the suppression of acute energy intake.Radhika V Seimon, Kylie Lange, Tanya J Little, Ixchel M Brennan, Amelia N Pilichiewicz, Kate L Feltrin, Astrid J Smeets, Michael Horowitz and Christine Feinle-Bisse

Gastrointestinal Sensing of Meal-Related Signals in Humans, and Dysregulations in Eating-Related Disorders

The upper gastrointestinal (GI) tract plays a critical role in sensing the arrival of a meal, including its volume as well as nutrient and non-nutrient contents. The presence of the meal in the stomach generates a mechanical distension signal, and, as gastric emptying progresses, nutrients increasingly interact with receptors on enteroendocrine cells, triggering the release of gut hormones, with lipid and protein being particularly potent. Collectively, these signals are transmitted to the brain to regulate appetite and energy intake, or in a feedback loop relayed back to the upper GI tract to further adjust GI functions, including gastric emptying. The research in this area to date has provided important insights into how sensing of intraluminal meal-related stimuli acutely regulates appetite and energy intake in humans. However, disturbances in the detection of these stimuli have been described in a number of eating-related disorders. This paper will review the GI sensing of meal-related stimuli and the relationship with appetite and energy intake, and examine changes in GI responses to luminal stimuli in obesity, functional dyspepsia and anorexia of ageing, as examples of eating-related disorders. A much better understanding of the mechanisms underlying these dysregulations is still required to assist in the development of effective management and treatment strategies in the future

Effects of Bitter Substances on GI Function, Energy Intake and Glycaemia-Do Preclinical Findings Translate to Outcomes in Humans?

Bitter substances are contained in many plants, are often toxic and can be present in spoiled food. Thus, the capacity to detect bitter taste has classically been viewed to have evolved primarily to signal the presence of toxins and thereby avoid their consumption. The recognition, based on preclinical studies (i.e., studies in cell cultures or experimental animals), that bitter substances may have potent effects to stimulate the secretion of gastrointestinal (GI) hormones and modulate gut motility, via activation of bitter taste receptors located in the GI tract, reduce food intake and lower postprandial blood glucose, has sparked considerable interest in their potential use in the management or prevention of obesity and/or type 2 diabetes. However, it remains to be established whether findings from preclinical studies can be translated to health outcomes, including weight loss and improved long-term glycaemic control. This review examines information relating to the effects of bitter substances on the secretion of key gut hormones, gastric motility, food intake and blood glucose in preclinical studies, as well as the evidence from clinical studies, as to whether findings from animal studies translate to humans. Finally, the evidence that bitter substances have the capacity to reduce body weight and/or improve glycaemic control in obesity and/or type 2 diabetes, and potentially represent a novel strategy for the management, or prevention, of obesity and type 2 diabetes, is explored