Independent influences of body mass and gastric volumes on satiation in humans

Contribution of ascites to impaired gastric function and nutritional intake in patients with cirrhosis and ascites

BACKGROUND & AIMS

Protein calorie malnutrition and weight loss are common among patients with cirrhosis and ascites. The cause of these symptoms is unclear, with several putative mechanisms proposed. The primary aims of this study were to compare gastric volumes and accommodation between patients with cirrhosis complicated by ascites and healthy controls, and to evaluate the effect of large-volume paracentesis in the patient group.

METHODS

Patients with cirrhosis and ascites underwent assessment of gastric volumes as measured by single-photon emission computed tomography, gastric sensation assessed by a validated nutrient drink test, and a 3-day assessment of caloric intake before and after large-volume paracentesis. Age- and sex-adjusted linear regression models were used to compare gastric volumes and accommodation ratios between patients and healthy volunteers. Paired Wilcoxon rank-sum tests were used to compare gastric measures before and after paracentesis among the patient group.

RESULTS

Fifteen patients (median age, 54 y) were compared with 112 healthy (age- and sex-matched) controls. Median postprandial gastric volumes (627 mL patients vs 721 healthy controls) and gastric accommodation were reduced significantly in patients compared with healthy controls (P = .02 and .006, respectively). After paracentesis: (1) fasting gastric volumes were increased (median 312 mL post- vs 241 mL pre-, P = .04), (2) patients tolerated ingestion of larger maximum volumes (median 964 mL post- vs 738 mL pre-, P = .04), and (3) caloric intake was increased (median 34% kcal post- vs 3110 kcal pre-, P = .005).

CONCLUSIONS

Postprandial gastric volumes and accommodation ratios are reduced in patients with cirrhosis and ascites compared with healthy controls. In addition, large-volume paracentesis increases fasting gastric volumes, volumes ingested until maximal satiation, and caloric intake.

Peptide YY, appetite and food intake

Obesity is taking on pandemic proportions. The laws of thermodynamics, however, remain unchanged, as energy will be stored if less energy is expended than consumed; the storage is usually in the form of adipose tissue. Several neural, humeral and psychological factors control the complex process known as appetite. Recently, a close evolutionary relationship between the gut and brain has become apparent. The gut hormones regulate important gastrointestinal functions such as motility, secretion, absorption, provide feedback to the central nervous system on availability of nutrients and may play a part in regulating food intake. Peptide YY (PYY) is a thirty-six amino acid peptide related to neuropeptide Y (NPY) and is co-secreted with glucagon-like peptide 1. Produced by the intestinal L-cells, the highest tissue concentrations of PYY are found in distal segments of the gastrointestinal tract, although it is present throughout the gut. Following food intake PYY is released into the circulation. PYY concentrations are proportional to meal energy content and peak plasma levels appear postprandially after 1 h. PYY3-36 is a major form of PYY in both the gut mucosal endocrine cells and the circulation. Peripheral administration of PYY3-36 inhibits food intake for several hours in both rodents and man. The binding of PYY3-36 to the Y2 receptor leads to an inhibition of the NPY neurones and a possible reciprocal stimulation of the pro-opiomelanocortin neurones. Thus, PYY3-36 appears to control food intake by providing a powerful feedback on the hypothalamic circuits. The effect on food intake has been demonstrated at physiological concentrations and, therefore, PYY3-36 may be important in the everyday regulation of food intake.

Nutrients and dyspepsia: paradigms and reality

PURPOSE OF REVIEW

Dyspepsia is a common disorder that presents as persistent or recurrent abdominal pain or discomfort in the upper abdomen and originates from organic or functional causes. Heterogeneous disorders, physiopathological, psychosomatic, sociocultural, demographic and genetic components have a great impact on its presentation. Physiopathological elements and the influence of nutrients on symptomatology are discussed to help establish clearer guidelines for treatment.

RECENT FINDINGS

Gastric emptying is affected by physiological, pharmacological and dietary factors and is translated into symptoms and signs such as anorexia, nausea, vomiting, weight loss and abdominal pain. Liquid or solid meals may cause early or delayed emptying, which is associated with symptoms of postprandial fullness. Abnormal glucose and electrolyte serum values may also cause transitory emptying delay. Fatty and acid nutrients have also been reported to aggravate symptoms of functional dyspepsia, especially after large meals. Studies have also pointed at food sensibility and the effect of Helicobacter pylori infection on gastric emptying in symptomatic patients. Patients may suffer antral hypomotility and total/partial postingestion pattern conversion. Spinal brain axis dysfunction caused by peripheral inflammation is associated with gastric dysmotility. An association between symptoms and functional polymorphisms is pending further clarification. It has been questioned whether the genotype is associated with a specific physiopathological mechanism, postinfectious functional disorders or psychological/social alterations.

SUMMARY

The treatment of dyspepsia is empiric and is directed at improving symptoms associated with alterations in emptying, postprandial accommodation, hypersensibility and hyperalgesia. Further studies are required to correlate symptoms with food kinetics at the initial postfood ingestion stages.

Gastric motor and sensory functions in obesity

In the vast majority of affected individuals, obesity involves overconsumption of food relative to calorie requirements. The sensory function of the stomach may play a key role in the cessation of food ingestion. This sensation of the stomach is, in part, determined by its motor functions, such as tone and compliance and the rate of emptying. However, studies of gastric emptying in normal-weight and obese persons have shown inconsistent results. Gastric capacity was larger in obese persons when tested with an intragastric latex balloon filled with water. In contrast, other studies using the barostat or imaging (single-photon emission computed tomography) techniques reported no differences in gastric volume or compliance between obese and lean subjects. On the other hand, increased body mass and fasting gastric volume are independently associated with delayed satiation under standard laboratory conditions of food ingestion. These data suggest that changes in gastric motor and sensory functions in obesity may present useful targets to prevent and treat obesity. Further well-controlled, validated studies are needed to clarify the potential role of altering the stomach's function as a means of controlling food intake in obesity.

Towards a better understanding of abdominal bloating and distension in functional gastrointestinal disorders

Abdominal bloating is an extremely common symptom affecting up to 96% of patients with functional gastrointestinal disorders and even 30% of the general population. To date bloating has often been viewed as being synonymous with an actual increase in abdominal girth, but recent evidence suggests that this is not necessarily the case. This review examines the relationship between the symptom of bloating and the physical sign of abdominal distension, as well as examining the epidemiology, pathophysiology and treatment options available for this debilitating aspect of the functional gastrointestinal disorders. Pathophysiological mechanisms explored include psychological factors, intestinal gas accumulation, fluid retention, food intolerance and malabsorption of sugars, weakness of abdominal musculature, and altered sensorimotor function. Treatment options are currently rather limited but include dietary changes, pharmacological approaches, probiotics and hypnotherapy.

Obesity and gastrointestinal sensory-motor function

Obesity has become a significant public health problem in the United States and has been associated with significant morbidity and mortality. Alterations in gastrointestinal sensory-motor function are now recognized to be associated with obesity and may be the cause of functional gastrointestinal symptoms commonly seen in these patients. The gut peptides are intimately involved in this process and may provide attractive therapeutic targets in the fight against this very morbid disease.

Appetite: measurement and manipulation misgivings

Humans appear to have a genotype that permits, or even encourages, an energy intake that is greater than energy expenditure when food is available. This was functional throughout most of human evolution but is less so in the current environment of inexpensive, palatable, and readily available foods. To achieve dietary goals of weight loss or maintenance, attempts have been made to influence appetitive sensations through the manipulation of the physical properties of foods, their composition, or their pattern of consumption. This has led to limited success, in part, because measurement of appetitive sensations is difficult but, more fundamentally, because the association between appetite and food choice or intake is not robust. This article critically reviews the most common methods for assessment of appetite and the effects of selected food constituents on appetitive sensations. Translation of current knowledge to dietetic practice must be made cautiously.

Postprandial plasma ghrelin is suppressed proportional to meal calorie content in normal-weight but not obese subjects

Circulating levels of the gastric hormone ghrelin rise before and decrease after a meal. In normal-weight subjects, postprandial suppression of ghrelin is proportional to calories consumed. Obese individuals have lower fasting ghrelin levels; however, it is unclear whether the obese show normal postprandial suppression. This study aimed to compare postprandial ghrelin responses in normal-weight and obese subjects, using mixed macronutrient meals with varied fat and calorie content. Postprandial ghrelin response was measured in normal-weight insulin-sensitive subjects and obese insulin-resistant subjects, after six test meals with different fat and calorie content (250-3000 kcal). Increasing the calorie content of meals in normal-weight subjects progressively lowered nadir levels of ghrelin. The obese had lower fasting ghrelin levels, and the reduction after the consumption of all test meals was less than the normal-weight subjects. The lowest postprandial levels in the obese were no different to the nadir in normal-weight volunteers after 1000-, 2000-, and 3000-kcal meals. Thus, circulating ghrelin levels decreased in normal-weight subjects after mixed meals. Obese subjects demonstrated a much reduced ghrelin postprandial suppression. This reduced suppression may influence satiety, thus reinforcing obesity.

GIH clinical research 2003-2004: the year in review

This article summarizes the clinical research advances in gastroenterology and hepatology that were reviewed during the Plenary Session of the American Gastroenterological Association's Annual Meeting in May 2004 in New Orleans, Louisiana. The clinical research advances included the efficacy of infliximab in the treatment of fistulizing Crohn's disease, survival after isolated intestinal transplantation, the role of endoscopic treatment of bleeding peptic ulcers and Barrett's esophagus, the recurrence of cancer after laparoscopic colectomy, the impact of microsatellite instability on the response to adjuvant chemotherapy with 5-fluorouracil (5-FU), the epidemiology of obesity and its response to low-carbohydrate diets, the potential role of gastrointestinal factors in the development of obesity, and, the newly appreciated condition, autoimmune pancreatitis with associated cholangitis. Clinical research advances will impact the management of digestive diseases.

Contributions of gastric volumes and gastric emptying to meal size and postmeal symptoms in functional dyspepsia

BACKGROUND & AIMS

The aim was to assess relative contributions of gastric volumes (GV) and gastric emptying (GE) to meal size and postprandial symptoms in patients with functional dyspepsia.

METHODS

Patients with chronic upper gastrointestinal symptoms were prospectively evaluated. GV during fasting and after 300 mL Ensure was measured with 99m Tc-single-photon emission computed tomography imaging and solid GE (99m Tc-egg) by scintigraphy. Maximum tolerated volume (MTV) and symptoms were measured after Ensure challenge.

RESULTS

Of 57 adult patients evaluated, 39 (23 women, 16 men) met Rome II criteria for functional dyspepsia and had no other diagnosis to account for dyspepsia. The most frequent symptoms were abdominal pain (90%), pain predominantly after meals (76%), nausea (85%), and early fullness after meals (79%). Relative to established laboratory normal values, MTV was abnormal in 82%, aggregate symptom score >209 in 72%, GE (at 1 hour) accelerated in 41%, GE (at 4 hours) delayed in 41%, and postmeal GV reduced in 52%. Lower body mass was associated with lower MTV and higher postchallenge symptoms. Lower fasting (not postprandial) GV and faster GE were independent predictors of lower MTV, explaining 18% of the variance after adjusting for body weight (32% of variance). GE was an independent predictor of postchallenge symptoms (10% of variance) after adjusting for volume ingested (10%), age (20%), and weight (10%).

CONCLUSIONS

In adults with functional dyspepsia seen in a tertiary referral practice, decreased meal size and postmeal symptoms are associated with low fasting GV and faster GE. These data provide physiologic targets for ameliorating symptoms of functional dyspepsia.

Effect of oral CCK-1 agonist GI181771X on fasting and postprandial gastric functions in healthy volunteers

CCK influences satiation and gastric and gallbladder emptying. GI181771X is a novel oral CCK-1 agonist; its effects on gastric emptying of solids, accommodation, and postprandial symptoms are unclear. Effects of four dose levels of the oral CCK-1 agonist GI181771X and placebo on gastric functions and postprandial symptoms were compared in 61 healthy men and women in a randomized, gender-stratified, double-blind, double-dummy placebo-controlled, parallel group study. Effects of 0.1, 0.5, and 1.5 mg of oral solution and a 5.0-mg tablet of GI181771X on gastric emptying of solids by scintigraphy, gastric volume by (99m)Tc-single photon emission computed tomographic imaging, maximum tolerated volume of Ensure, and postprandial nausea, bloating, fullness, and pain were studied. On each of 3 study days, participants received their randomly assigned treatment. Adverse effects and safety were monitored. There were overall group effects of GI181771X on gastric emptying (P < 0.01) and fasting and postprandial volumes (P = 0.036 and 0.015, respectively). The 1.5-mg oral solution of GI181771X significantly delayed gastric emptying of solids (P < 0.01) and increased fasting (P = 0.035) gastric volumes without altering postprandial (P = 0.056) gastric volumes or postprandial symptoms relative to placebo. The effect of the 5.0-mg tablet on gastric emptying of solids did not reach significance (P = 0.052). Pharmacokinetic profiles showed the highest area under the curve over 4 h for the 1.5-mg solution and a similar area under the curve for the 0.5-mg solution and 5-mg tablet. Adverse effects were predominantly gastrointestinal and occurred in a minority of participants. GI181771X delays gastric emptying of solids and exhibits an acceptable safety profile in healthy participants. CCK-1 receptors can be modulated to increase fasting gastric volume.

Association of upper and lower gastrointestinal tract symptoms with body mass index in an Australian cohort

Food modulates gastrointestinal (GI) function and GI symptoms could alter food intake, but it is not established whether or not obese people experience more or less GI symptoms. We aimed at evaluating the association between body mass index (BMI) and specific GI symptoms in the community. Population-based random samples from Sydney, Australia (n = 777) completed a validated questionnaire. The association of each GI symptom with BMI (kg m(-2)) categories was assessed using logistic regression analysis adjusting for potential confounders. The prevalence of obesity (BMI > or =30 kg m(-2)) was 22%. There were univariate associations (adjusting for age, sex, education level, alcohol and smoking) between increased BMI category and heartburn (OR = 1.9, 95% CI 1.4, 2.5), acid regurgitation (OR = 2.1, 95% CI 1.4, 2.9), increased bloating (OR = 1.3, 95%CI 1.1, 1.6), increased stool frequency (OR = 1.4, 95% CI 1.1, 1.7), loose and watery stools (OR = 1.5, 95% CI 1.1, 2.0) and upper abdominal pain (OR = 1.3, 95% CI 1.03, 1.6). Early satiety was associated with a lower BMI category but this was not significant after adjustment (OR = 0.8, 95% CI 0.6, 1.1). Lower abdominal pain, postprandial fullness, nausea and vomiting were not associated with BMI category. In a regression model adjusting for sex, education, smoking, alcohol and all GI symptoms, older age, less early satiety and increased stool frequency and heartburn were all independently associated with increasing BMI (all P < 0.01). Heartburn and diarrhoea were associated with increased BMI, while early satiety was associated with a lower BMI in this population.