Gallbladder motility and gallstone formation in obese patients following very low calorie diets. Use it (fat) to lose it (well)

Myths and Facts Regarding Low-Carbohydrate Diets

As the prevalence of chronic diseases persists at epidemic proportions, health practitioners face ongoing challenges in providing effective lifestyle treatments for their patients. Even for those patients on GLP-1 agonists, nutrition counseling remains a crucial strategy for managing these conditions over the long term. This paper aims to address the concerns of patients and practitioners who are interested in a low-carbohydrate or ketogenic diet, but who have concerns about its efficacy, safety, and long-term viability. The authors of this paper are practitioners who have used this approach and researchers engaged in its study. The paper reflects our opinion and is not meant to review low-carbohydrate diets systematically. In addressing common concerns, we hope to show that this approach has been well researched and can no longer be seen as a "fad diet" with adverse health effects such as impaired renal function or increased risk of heart disease. We also address persistent questions about patient adherence, affordability, and environmental sustainability. This paper reflects our perspective as clinicians and researchers engaged in the study and application of low-carbohydrate dietary interventions. While the paper is not a systematic review, all factual claims are substantiated with citations from the peer-reviewed literature and the most rigorous and recent science. To our knowledge, this paper is the first to address potential misconceptions about low-carbohydrate and ketogenic diets comprehensively.

Gallstones after bariatric surgery: mechanisms and prophylaxis

Gallstones represent a common yet often underappreciated complication following bariatric surgery, with reported incidence rates ranging widely from 10.4% to 52.8% within the first postoperative year. Multiple factors contribute to gallstone formation in this setting, including intraoperative injury to the hepatic branch of the vagus nerve, alterations in bile composition, reduced food intake, shifts in gastrointestinal hormone levels, and dysbiosis of the gut microbiota. Notably, the risk of cholelithiasis varies by surgical procedure, with sleeve gastrectomy (SG) generally associated with a lower incidence compared to Roux-en-Y gastric bypass (RYGB). Prophylactic cholecystectomy during bariatric surgery may benefit patients with preexisting gallstones, whereas preserving the hepatic branch of the vagus is an important technical consideration, particularly in RYGB, to mitigate postoperative gallstone risk. Pharmacological interventions, such as ursodeoxycholic acid (UDCA), have demonstrated efficacy in preventing gallstones and reducing subsequent cholecystectomy rates. However, consensus is lacking on the optimal dosing, duration, and administration frequency of UDCA across different bariatric procedures. Additionally, dietary measures, such as moderate fat intake or fish oil supplementation, have shown promise in alleviating lithogenic processes. Emerging evidence supports the use of probiotics as a safe and patient-friendly adjunct or alternative to UDCA, given their ability to improve gut dysbiosis and reduce gallstone formation. Further high-quality studies are needed to define standardized prophylactic strategies that balance efficacy with patient adherence, offering personalized gallstone prevention protocols in the era of widespread bariatric surgery.

High serum uric acid levels are associated with increased prevalence of gallstones in adult women: a cross-sectional study based on NHANES

Objective

We investigated the association between serum uric acid (SUA) levels and gallstone (GS) prevalence in adult women.

Methods

Participants' information were taken from the United States National Health and Nutrition Examination Survey (2017-2020). Logistic regression analysis and dose-response curve were used to assess the association between SUA levels and the prevalence of GS in adult women. Subgroup analyses were performed to investigate associations between SUA levels and age, ethnicity, body mass index, hypertension, and diabetes.

Results

A total of 600 participants self-reported a history of GS. After adjusting for confounding, the prevalence of GS in adult women increased by 14% for every 1 mg/dL increase in SUA (odds ratio [OR]: 1.14, 95% confidence interval [CI]: 1.06, 1.22). Testing SUA as a categorical variable for sensitivity analyses indicated a 1.6-fold increase in the prevalence of GS in tertile 3 (OR=1.60, 95% CI: 1.25, 2.04) compared to tertile 1. Dose-response curves showed a nonlinear correlation between SUA levels and the prevalence of GS. Subgroup analyses indicated that SUA level was associated with an increased prevalence of GS in most subgroups, although subtle differences existed.

Conclusion

SUA was positively and non-linearly associated with the prevalence of GS in adult females. Despite the inability to clarify the causal relationship between them, our results remain interesting.

Non-linear relationship between the first meal time of the day and gallstone incidence in American adults: a population-based cross-sectional study

Background

Irregular meal time is associated with gallstones. The time-dose effect between meal time and gallstone formation remains unknown.

Objective

This study aimed to investigate the association between the first meal time (FMT) of the day and the prevalence of gallstones.

Methods

Based on data from the National Health and Nutrition Examination Survey from 2017 to March 2020, the associations between the FMT of the day and the prevalence of gallstones were analyzed via multivariable logistic regression, restricted cubic spline curves, subgroup analysis, and interaction tests.

Results

A total of 6,547 participants were included. The fully adjusted model indicated a positive correlation between the FMT of the day and the prevalence of gallstones (odds ratio [OR] = 1.05, 95% confidence interval [CI] = 1.02 ~ 1.08); this association was consistent across subgroups. The risk of developing gallstones was the greatest when the FMT was between 09:00 and 14:00 (OR [95% CI] = 1.49 [1.24 ~ 1.77]). There was a non-linear relationship between the FMT and gallstone incidence (P for non-linearity = 0.042), with an inflection point at 13.4 h. After the 13.4-h mark, the risk of developing gallstones did not increase further.

Conclusion

The FMT of the day is positively correlated with the prevalence of gallstones, and there is a non-linear relationship and threshold effect between the two. Skipping breakfast is associated with a greater risk of developing gallstones. This study provides new evidence for the dietary prevention of gallstones.

Protein Phosphatase 1 Regulatory Subunit 3 Beta rs4240624 Genotype Is Associated With Gallstones and With Significant Changes in Bile Lipidome

Background and Aims

Gallstone disease (GSD) associates with significant morbidity and mortality. Decreased secretion of bile acids has been suggested as a driving factor for GSD. Recently, we linked the protein phosphatase 1 regulatory subunit 3 beta (PPP1R3B) rs4240624 genotype to decreased bile acid levels in bile. In this study, we investigated whether these individuals had an increased risk for GSD as well as the differences in the lipid composition of the gallbladder bile of these individuals compared to controls and patients with GSD.

Methods

Bile acids, cholesterol, and phospholipid levels in gallbladder bile samples were enzymatically measured in 46 patients (34 female, age 45.7 ± 9.8 years, BMI 41.3 ± 4.4 kg/m2) who underwent elective laparoscopic Roux-en-Y gastric bypass. The lipidome of gallbladder bile was analyzed using high-performance liquid chromatography-mass spectrometry. Gallstone status was evaluated using abdominal ultrasonography before the surgery.

Results

The G allele of PPP1R3B rs4240624 was significantly associated with GSD in patients with obesity. We validated this association in the UK Biobank. Bile lipidomics demonstrated that 13 of the 17 minor lipid classes measured were higher in individuals with the G allele. The concentrations of bile acids, cholesterol, and phospholipids, as well as the cholesterol saturation index, were lower in patients with GSD than in those without gallstones. GSD had an effect similar to that of PPP1R3B genotype on minor lipids.

Conclusion

The PPP1R3B rs4240624 genotype is associated with gallstones and with changes in gallbladder bile similar to those observed in patients with gallstones, suggesting that the PPP1R3B genotype contributes to the risk of gallstones by altering the bile lipidome.

Modified dietary fat intake for treatment of gallstone disease in people of any age

BACKGROUND

The prevalence of gallstones varies between less than 1% and 64% in different populations and is thought to be increasing in response to changes in nutritional intake and increasing obesity. Some people with gallstones have no symptoms but approximately 2% to 4% develop them each year, predominantly including severe abdominal pain. People who experience symptoms have a greater risk of developing complications. The main treatment for symptomatic gallstones is cholecystectomy. Traditionally, a low-fat diet has also been advised to manage gallstone symptoms, but there is uncertainty over the evidence to support this.

OBJECTIVES

To evaluate the benefits and harms of modified dietary fat intake in the treatment of gallstone disease in people of any age.

SEARCH METHODS

We searched the Cochrane Hepato-Biliary Group Controlled Trials Register, the Cochrane Central Register of Controlled Trials in the Cochrane Library, MEDLINE ALL Ovid, Embase Ovid, and three other databases to 17 February 2023 to identify randomised clinical trials in people with gallstones. We also searched online trial registries and pharmaceutical company sources, for ongoing or unpublished trials to March 2023.

SELECTION CRITERIA

We included randomised clinical trials (irrespective of language, blinding, or status) in people with gallstones diagnosed using ultrasonography or conclusive imaging methods. We excluded participants diagnosed with another condition that may compromise dietary fat tolerance. We excluded trials where data from participants with gallstones were not reported separately from data from participants who did not have gallstones. We included trials that investigated other interventions (e.g. trials of drugs or other dietary (non-fat) components) providing that the trial groups had received the same proportion of drug or other dietary (non-fat) components in the intervention.

DATA COLLECTION AND ANALYSIS

We intended to undertake meta-analysis and present the findings according to Cochrane recommendations. However, as we identified only five trials, with data unsuitable and insufficient for analyses, we described the data narratively.

MAIN RESULTS

We included five trials but only one randomised clinical trial (69 adults), published in 1986, reported outcomes of interest to the review. The trial had four dietary intervention groups, three of which were relevant to this review. We assessed the trial at high risk of bias. The dietary fat modifications included a modified cholesterol intake and medium-chain triglyceride supplementation. The control treatment was a standard diet. The trial did not report on any of the primary outcomes in this review (i.e. all-cause mortality, serious adverse events, and health-related quality of life). The trial reported on gallstone dissolution, one of our secondary outcomes. We were unable to apply the GRADE approach to determine certainty of evidence because the included trial did not provide data that could be used to generate an estimate of the effect on this or any other outcome. The trial expressed its finding as "no significant effect of a low-cholesterol diet in the presence of ursodeoxycholic acid on gallstone dissolution." There were no serious adverse events reported. The included trial reported that they received no funding that could bias the trial results through conflicts of interest. We found no ongoing trials.

AUTHORS' CONCLUSIONS

The evidence about the effects of modifying dietary fat on gallstone disease versus standard diet is scant. We lack results from high-quality randomised clinical trials which investigate the effects of modification of dietary fat and other nutrient intakes with adequate follow-up. There is a need for well-designed trials that should include important clinical outcomes such as mortality, quality of life, impact on dissolution of gallstones, hospital admissions, surgical intervention, and adverse events.

Evidence-based clinical practice guidelines for cholelithiasis 2021

The Japanese Society of Gastroenterology first published evidence-based clinical practice guidelines for cholelithiasis in 2010, followed by a revision in 2016. Currently, the revised third edition was published to reflect recent evidence on the diagnosis, treatment, and prognosis of cholelithiasis conforming to the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system. Following this revision, the present English version of the guidelines was updated and published herein. The clinical questions (CQ) in the previous version were reviewed and rearranged into three newly divided categories: background questions (BQ) dealing with basic background knowledge, CQ, and future research questions (FRQ), which refer to issues that require further accumulation of evidence. Finally, 52 questions (29 BQs, 19 CQs, and 4 FRQs) were adopted to cover the epidemiology, pathogenesis, diagnosis, treatment, complications, and prognosis. Based on a literature search using MEDLINE, Cochrane Library, and Igaku Chuo Zasshi databases for the period between 1983 and August 2019, along with a manual search of new information reported over the past 5 years, the level of evidence was evaluated for each CQ. The strengths of recommendations were determined using the Delphi method by the committee members considering the body of evidence, including benefits and harms, patient preference, and cost-benefit balance. A comprehensive flowchart was prepared for the diagnosis and treatment of gallbladder stones, common bile duct stones, and intrahepatic stones, respectively. The current revised guidelines are expected to be of great assistance to gastroenterologists and general physicians in making decisions on contemporary clinical management for cholelithiasis patients.

Fasting and refeeding triggers specific changes in bile acid profiles and gut microbiota

BACKGROUND

Bile acids (BAs) are closely related to nutrient supply and modified by gut microbiota. Gut microbiota perturbations shape BA composition, which further affects host metabolism.

METHODS

We investigated BA profiles in plasma, feces, and liver of mice fed ad libitum, fasted for 24 h, fasted for 24 h and then refed for 24 h using ultraperformance liquid chromatography coupled to tandem mass spectrometry. Gut microbiota was measured by 16S rRNA gene sequencing. Expressions of BA biosynthesis-related genes in the liver and BA reabsorption-related genes in the ileum were analyzed.

FINDINGS

Compared with the controls, unconjugated primary BAs (PBAs) and unconjugated secondary BAs (SBAs) in plasma were decreased whereas conjugated SBAs in plasma, unconjugated PBAs, unconjugated SBAs and conjugated SBAs in feces, and unconjugated SBAs in liver were increased in the fasting mice. The expression of BA biosynthesis-related genes in the liver and BA reabsorption-related genes in the ileum were decreased in the fasting mice compared with the controls. Compared with the controls, Akkermansia, Parabacteroides, Muribaculum, Eubacterium_coprostanoligenes and Muribaculaceae were increased in the fasting mice whereas Lactobacillus and Bifidobacterium were decreased. All these changes in BAs and gut microbiota were recovered under refeeding. Akkermansia was negatively correlated with plasma levels of unconjugated PBAs, unconjugated SBAs and glucose, whereas it was positively correlated with plasma conjugated SBAs, fecal unconjugated PBAs, and fecal unconjugated SBAs.

CONCLUSIONS

We characterized the BA profiles, gut microbiota, and gene expression responsible for BA biosynthesis and intestinal reabsorption to explore their rapid changes in response to food availability. Our study highlighted the rapid effect of nutrient supply on BAs and gut microbiota.

Effectiveness of diet, psychological, and exercise therapies for the management of bile acid diarrhoea in adults: A systematic review

BACKGROUND

Bile acid diarrhoea (BAD) causes chronic diarrhoea and is primarily treated pharmacologically. This systematic review aimed to evaluate the effectiveness of non-pharmacological therapies for evidence-based management of BAD in adults.

METHODS

A systematic review of the medical literature was performed from 1975 to 13 July 2021 to identify studies on diet, psychological, and exercise therapies that met diagnostic criteria for BAD in adults with diarrhoea. Effectiveness was judged by responder or improvement in diarrhoea at study endpoint according to each study's definition of diarrhoea. Therapeutic effect on abdominal pain and flatulence was also measured. Risk of bias was assessed using the Risk Of Bias In Non-Randomised Studies of Interventions tool. A narrative review was conducted using 'Synthesis Without Meta-analysis' guidance. Certainty of the evidence was assessed using Grading of Recommendations Assessment, Development, and Evaluation.

RESULTS

Eight prospective cohort studies were identified on diet therapies from 2 weeks to over 2 years involving 192 patients. No psychological or exercise therapies were found. Carbohydrate modification (one study, n = 2) in primary BAD, and dietary fat intake reductions (five studies, n = 181) and an exclusive elemental diet therapy (two studies, n = 9) in secondary BAD, showed beneficial directions of effect on diarrhoea, abdominal pain, and flatulence. Risks of bias for each study and across studies for each therapy type were serious. Certainty of the evidence was very low for all outcomes.

CONCLUSIONS

No conclusions could be drawn on the effectiveness of diet, psychological, or exercise therapies on diarrhoea, abdominal pain, and flatulence for the management of BAD in adults. High-quality randomised controlled trials are needed.

Diets for weight management in adults with type 2 diabetes: an umbrella review of published meta-analyses and systematic review of trials of diets for diabetes remission

AIMS/HYPOTHESIS

Weight reduction is fundamental for type 2 diabetes management and remission, but uncertainty exists over which diet type is best to achieve and maintain weight loss. We evaluated dietary approaches for weight loss, and remission, in people with type 2 diabetes to inform practice and clinical guidelines.

METHODS

First, we conducted a systematic review of published meta-analyses of RCTs of weight-loss diets. We searched MEDLINE (Ovid), PubMed, Web of Science and Cochrane Database of Systematic Reviews, up to 7 May 2021. We synthesised weight loss findings stratified by diet types and assessed meta-analyses quality with A Measurement Tool to Assess Systematic Reviews (AMSTAR) 2. We assessed certainty of pooled results of each meta-analysis using Grading of Recommendations, Assessment, Development and Evaluations (GRADE) (PROSPERO CRD42020169258). Second, we conducted a systematic review of any intervention studies reporting type 2 diabetes remission with weight-loss diets, in MEDLINE (via PubMed), Embase and Cochrane Central Register of Controlled Trials, up to 10 May 2021. Findings were synthesised by diet type and study quality (Cochrane Risk of Bias tool 2.0 and Risk Of Bias In Non-randomised Studies - of Interventions [ROBINS-I]), with GRADE applied (PROSPERO CRD42020208878).

RESULTS

We identified 19 meta-analyses of weight-loss diets, involving 2-23 primary trials (n = 100-1587), published 2013-2021. Twelve were 'critically low' or 'low' AMSTAR 2 quality, with seven 'high' quality. Greatest weight loss was reported with very low energy diets, 1.7-2.1 MJ/day (400-500 kcal) for 8-12 weeks (high-quality meta-analysis, GRADE low), achieving 6.6 kg (95% CI -9.5, -3.7) greater weight loss than low-energy diets (4.2-6.3 MJ/day [1000-1500 kcal]). Formula meal replacements (high quality, GRADE moderate) achieved 2.4 kg (95% CI -3.3, -1.4) greater weight loss over 12-52 weeks. Low-carbohydrate diets were no better for weight loss than higher-carbohydrate/low-fat diets (high quality, GRADE high). High-protein, Mediterranean, high-monounsaturated-fatty-acid, vegetarian and low-glycaemic-index diets all achieved minimal (0.3-2 kg) or no difference from control diets (low to critically low quality, GRADE very low/moderate). For type 2 diabetes remission, of 373 records, 16 met inclusion criteria. Remissions at 1 year were reported for a median 54% of participants in RCTs including initial low-energy total diet replacement (low-risk-of-bias study, GRADE high), and 11% and 15% for meal replacements and Mediterranean diets, respectively (some concerns for risk of bias in studies, GRADE moderate/low). For ketogenic/very low-carbohydrate and very low-energy food-based diets, the evidence for remission (20% and 22%, respectively) has serious and critical risk of bias, and GRADE certainty is very low.

CONCLUSIONS/INTERPRETATION

Published meta-analyses of hypocaloric diets for weight management in people with type 2 diabetes do not support any particular macronutrient profile or style over others. Very low energy diets and formula meal replacement appear the most effective approaches, generally providing less energy than self-administered food-based diets. Programmes including a hypocaloric formula 'total diet replacement' induction phase were most effective for type 2 diabetes remission. Most of the evidence is restricted to 1 year or less. Well-conducted research is needed to assess longer-term impacts on weight, glycaemic control, clinical outcomes and diabetes complications.

Gallstone Formation Follows a Different Trajectory in Bariatric Patients Compared to Nonbariatric Patients

Since obese patients form cholesterol gallstones very rapidly after bariatric surgery, in patients who did not form gallstones during preceding years, we hypothesized that gallstone formation follows a different trajectory in bariatric patients compared to nonbariatric patients. We therefore analyzed the lipid composition of gallbladder bile derived from 18 bariatric gallstone patients and 17 nonbariatric gallstone patients (median (IQR) age, 46.0 (28.0-54.0) years; 33 (94%) female) during laparoscopic cholecystectomy using an enzymatic and lipidomics approach. We observed a higher concentration of total lipids (9.9 vs. 5.8 g/dL), bile acids (157.7 vs. 81.5 mM), cholesterol (10.6 vs. 5.4 mM), and phospholipids (30.4 vs. 21.8 mM) in bariatric gallstone patients compared to nonbariatric gallstone patients. The cholesterol saturation index did not significantly differ between the two groups. Lipidomics analysis revealed an interesting pattern. Enhanced amounts of a number of lipid species were found in the gallbladder bile of nonbariatric gallstone patients. Most striking was a fivefold higher amount of triglyceride. A concomitant ninefold increase of apolipoprotein B was found, suggesting secretion of triglyceride-rich lipoproteins (TRLs) at the canalicular pole of the hepatocyte in livers from nonbariatric gallstone patients. These findings suggest that gallstone formation follows a different trajectory in bariatric patients compared to nonbariatric patients. Impaired gallbladder emptying might explain the rapid gallstone formation after bariatric surgery, while biliary TRL secretion might contribute to gallstone formation in nonbariatric patients.

Excess Body Weight and Gallstone Disease

Background

Approximately one fifth of adults are diagnosed with gallstones worldwide. Of these, around 25% develop gallstone disease (indicated by the presence of symptoms) and undergo cholecystectomy.

Summary

The risk of gallstones is influenced by a combination of genetic and lifestyle factors, such as excess body weight. In fact, body mass has been demonstrated to be a major risk factor for symptomatic gallstones. Rapid weight loss can also initiate a prolithogenic state and further increase the likelihood of either gallstone formation or existing gallstones becoming symptomatic; however, sensible weight loss strategies can mitigate this risk. This review discusses the role of excess body weight and the risk of gallstone disease, as well as the options available for the prevention of symptomatic gallstones.

Key Messages

Healthy weight loss diets combined with regular physical activity can promote successful weight loss and weight maintenance and reduce the risk of gallstones. Should rapid weight loss be required for health reasons or be expected, e.g., after bariatric surgery, prophylactic ursodeoxycholic acid during the period of weight reduction has been demonstrated to reduce the incidence of gallstones formation or symptomatic gallstone occurrence. The recent German guidelines on gallstones recommend simultaneous cholecystectomy during bariatric surgery but only for those with preexisting symptomatic stones.

Caloric restriction disrupts the microbiota and colonization resistance

Diet is a major factor that shapes the gut microbiome1, but the consequences of diet-induced changes in the microbiome for host pathophysiology remain poorly understood. We conducted a randomized human intervention study using a very-low-calorie diet (NCT01105143). Although metabolic health was improved, severe calorie restriction led to a decrease in bacterial abundance and restructuring of the gut microbiome. Transplantation of post-diet microbiota to mice decreased their body weight and adiposity relative to mice that received pre-diet microbiota. Weight loss was associated with impaired nutrient absorption and enrichment in Clostridioides difficile, which was consistent with a decrease in bile acids and was sufficient to replicate metabolic phenotypes in mice in a toxin-dependent manner. These results emphasize the importance of diet-microbiome interactions in modulating host energy balance and the need to understand the role of diet in the interplay between pathogenic and beneficial symbionts.

Statement on additional scientific evidence in relation to the essential composition of total diet replacement for weight control

Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to revise the Opinion on the essential composition of total diet replacements for weight control (TDRs) regarding the minimum content of linoleic acid (LA) and alpha-linolenic acid (ALA) and the maximum content of magnesium (Mg). Through a comprehensive literature search, human studies were retrieved reporting on LA and ALA concentrations in adipose tissue (AT), on weight loss and gallstone formation following TDR consumption and on diarrhoea after supplemental Mg intake. The distribution of the amount of LA and ALA release from AT during weight loss when consuming TDRs was estimated using statistical simulations. Using the fifth percentile, the coverage of the adequate intake (AI) for both FA was estimated. For the risk of developing diarrhoea when consuming TDRs with an Mg content of 350 mg/day, four cross-over studies using 360-368 mg Mg/day were reviewed. The Panel concludes that (1) there is no need to add LA to TDRs, as the amount released from AT during weight loss when consuming TDRs is sufficient to cover the AI for LA; (2) a minimum of 0.8 g/day ALA is needed in TDRs in order to meet the AI for ALA; (3) the minimum fat content of TDRs of 20 g/day as derived in the Panel's previous opinion is proposed to be maintained until the availability of further evidence, given the considerable uncertainty as to the amount of fat required for reducing the risk of gallstone formation; and (4) the likelihood that Mg-induced diarrhoea occurs at a severity that may be considered of concern for overweight and obese individuals consuming TDRs is low when the total maximum Mg content in TDRs is 350 mg/day.

The Effects of Very Low Energy Diets and Low Energy Diets with Exercise Training on Skeletal Muscle Mass: A Narrative Review

In recent years, very-low-energy diets (VLEDs) have been recognised as a viable strategy for improving the extent of weight loss and cardio-metabolic outcomes in people who are either overweight or obese. However, concerns exist regarding the reductions in lean body mass (LBM) during VLEDs, particularly in vulnerable demographic groups, such as middle-aged and older adults already prone to developing sarcopenia. Sarcopenia is itself associated with multiple adverse outcomes, including frailty, cardio-metabolic deterioration and increased mortality. Therefore, a number of studies investigating strategies to ameliorate this detrimental effect of VLEDs have attempted to address this concern. This narrative review explores the potential benefits and limitations of exercise and/or protein supplementation for LBM retention during VLEDs based on the available evidence. Current studies suggest that both protein supplementation and exercise training may result in improved LBM retention (and skeletal muscle function) during VLEDs. However, uncertainty remains concerning the interactions between intervention types, based on discordant outcomes reported in the literature and the heterogeneity of exercise modalities in achieving this particular outcome.

Pathophysiological connections between gallstone disease, insulin resistance, and obesity

Obesity and cholesterol gallstone disease (GSD) are frequently coexisting diseases; therefore and considering the current worldwide obesity epidemics, a precise understanding of the pathophysiological relationships between GSD and insulin resistance (IR) is important. Classically, obesity has been understood as a risk factor for GSD and the gallbladder (GB) viewed as a simple bile reservoir, with no metabolic roles whatsoever. However, consistent evidence has showed that both GSD and cholecystectomy associates with fatty liver and IR, raising the possibility that the GB is indeed an organ with metabolic regulatory roles. Herein, we review the pathophysiological mechanisms by which GSD, IR, and obesity are interconnected, with emphasis in the actions of the GB as a regulator of bile acids kinetics and a hormone secreting organ, with metabolic actions at the systemic level. We also examine the relationships between increased hepatic lipogenic in IR states and GSD pathogenesis. We propose a model in which GSD and hepatic IR mutually interact to determine a state of dysregulated lipid and energy metabolism that potentiate the metabolic dysregulation of obesity.

[Nutritional intervention in the control of gallstones and renal lithiasis]

INTRODUCTION

Cholelithiasis and kidney stones are frequent pathologies in developed countries. Gallstones can be pigmentary, cholesterol (75%) or mixed. Age, female sex, obesity, rapid weight loss, consumption of refined sugars, saturated fat, iron deficiency, vitamin D and low intake of fiber and vitamin C are factors associated with an increased risk of cholelithiasis. On the other hand, the intake of ω-3 fatty acids, oleic acid, calcium, magnesium, fiber, fruits and vegetables, dairy products, nuts, coffee, moderate consumption of alcohol, vitamin C supplements, physical exercise and a regular diet have a protective paper. The most frequent kidney stones are calcium oxalate followed by mixed ones (oxalate and calcium phosphate), struvite, uric acid and cystine. A high water intake is recommended (> 2.5 l / day), varying the type of recommended or unadvisable food depending on the type of calculus. In oxalic lithiasis it is recommended to reduce the consumption of meat, moderate that of spinach, Swiss chard, asparagus, chocolate and avoid excessive sodium intake. The administration of oxalate-degrading probiotics (Lactobacillus) may reduce intestinal absorption, although further studies are necessary to corroborate these results. In calcium phosphate acidifying diet is recommended and limit the consumption of coffee and tea. The prevention of uric calculus is based on hydration with alkalizing drinks and vegetarian diet, decreasing foods rich in purines (liver, kidney, fish eggs, anchovies, sardines and seafood) and in calculus of cystine diet is recommended alkalizing. Since the formation of struvite calculi is due to urinary infections, pharmacological treatment and the consumption of acidifying diets, moderation of the intake of phosphate-rich foods and limiting the contribution of fats and citrus fruits are necessary. The nutritional intervention is an effective measure in the prevention of biliary and renal lithiasis and prevent its recurrence.

Effects of Diets on Adipose Tissue

BACKGROUND

Obesity is a major health problem that has become a global epidemic. Overweight and obesity are commonly associated with the development of several pathologies, such as insulin resistance, cardiovascular diseases, sleep apnea and several types of cancer, which can lead to further morbidity and mortality. An increased abdominal adiposity renders overweight and obese individuals more prone to metabolic and cardiovascular problems.

OBJECTIVE

This Review aims to describe the dietary strategies to deal with excess adiposity given the medical, social and economic consequences of obesity.

METHODS

One hundred and eighty-five papers were included in the present Review.

RESULTS

Excess adiposity leads to several changes in the biology, morphology and function of the adipose tissue, such as adipocyte hypertrophy and hyperplasia, adipose tissue inflammation and fibrosis and an impaired secretion of adipokines, contributing to the onset of obesity- related comorbidities. The first approach for obesity management and prevention is the implementation of a diet combined with physical activity. The present review summarizes the compelling evidence showing body composition changes, impact on cardiometabolism and potential adverse effects of very-low calorie, low- and high-carbohydrate, high-protein or low-fat diets. The use of macronutrients during the preprandial and postprandial state has been also reviewed to better understand the metabolic changes induced by different dietary interventions.

CONCLUSION

Dietary changes should be individualised, tailored to food preferences and allow for flexible approaches to reducing calorie intake in order to increase the motivation and compliance of overweight and obese patients.

The Role of Diet in the Pathogenesis of Cholesterol Gallstones

Cholesterol gallstone disease is a major health problem in Westernized countries and depends on a complex interplay between genetic factors, lifestyle and diet, acting on specific pathogenic mechanisms. Overweigh, obesity, dyslipidemia, insulin resistance and altered cholesterol homeostasis have been linked to increased gallstone occurrence, and several studies point to a number of specific nutrients as risk- or protective factors with respect to gallstone formation in humans. There is a rising interest in the identification of common and modifiable dietetic factors that put the patients at risk of gallstones or that are able to prevent gallstone formation and growth. In particular, dietary models characterized by increased energy intake with highly refined sugars and sweet foods, high fructose intake, low fiber contents, high fat, consumption of fast food and low vitamin C intake increase the risk of gallstone formation. On the other hand, high intake of monounsaturated fats and fiber, olive oil and fish (ω-3 fatty acids) consumption, vegetable protein intake, fruit, coffee, moderate alcohol consumption and vitamin C supplementation exert a protective role. The effect of some confounding factors (e.g., physical activity) cannot be ruled out, but general recommendations about the multiple beneficial effects of diet on cholesterol gallstones must be kept in mind, in particular in groups at high risk of gallstone formation.

Comparison of Very Low Energy Diet Products Available in Australia and How to Tailor Them to Optimise Protein Content for Younger and Older Adult Men and Women

Very low energy diets (VLED) are efficacious in inducing rapid weight loss but may not contain adequate macronutrients or micronutrients for individuals with varying nutritional requirements. Adequate protein intake during weight loss appears particularly important to help preserve fat free mass and control appetite, and low energy and carbohydrate content also contributes to appetite control. Therefore, the purpose of this study was to compare the nutritional content (with a focus on protein), nutritional adequacy and cost of all commercially-available VLED brands in Australia. Nutritional content and cost were extracted and compared between brands and to the Recommended Dietary Intake (RDI) or adequate intake (AI) of macronutrients and micronutrients for men and women aged 19-70 years or >70 years. There was wide variability in the nutritional content, nutritional adequacy and cost of VLED brands. Most notably, even brands with the highest daily protein content, based on consuming three products/day (KicStart™ and Optislim(®), ~60 g/day), only met estimated protein requirements of the smallest and youngest women for whom a VLED would be indicated. Considering multiple options to optimise protein content, we propose that adding pure powdered protein is the most suitable option because it minimizes additional energy, carbohydrate and cost of VLEDs.

Gallstones

Gallstones grow inside the gallbladder or biliary tract. These stones can be asymptomatic or symptomatic; only gallstones with symptoms or complications are defined as gallstone disease. Based on their composition, gallstones are classified into cholesterol gallstones, which represent the predominant entity, and bilirubin ('pigment') stones. Black pigment stones can be caused by chronic haemolysis; brown pigment stones typically develop in obstructed and infected bile ducts. For treatment, localization of the gallstones in the biliary tract is more relevant than composition. Overall, up to 20% of adults develop gallstones and >20% of those develop symptoms or complications. Risk factors for gallstones are female sex, age, pregnancy, physical inactivity, obesity and overnutrition. Factors involved in metabolic syndrome increase the risk of developing gallstones and form the basis of primary prevention by lifestyle changes. Common mutations in the hepatic cholesterol transporter ABCG8 confer most of the genetic risk of developing gallstones, which accounts for ∼25% of the total risk. Diagnosis is mainly based on clinical symptoms, abdominal ultrasonography and liver biochemistry tests. Symptoms often precede the onset of the three common and potentially life-threatening complications of gallstones (acute cholecystitis, acute cholangitis and biliary pancreatitis). Although our knowledge on the genetics and pathophysiology of gallstones has expanded recently, current treatment algorithms remain predominantly invasive and are based on surgery. Hence, our future efforts should focus on novel preventive strategies to overcome the onset of gallstones in at-risk patients in particular, but also in the population in general.

The cholecystokinin-1 receptor antagonist devazepide increases cholesterol cholelithogenesis in mice

BACKGROUND

A defect in gallbladder contraction function plays a key role in the pathogenesis of gallstones. The cholecystokinin-1 receptor (CCK-1R) antagonists have been extensively investigated for their therapeutic effects on gastrointestinal and metabolic diseases in animal studies and clinical trials. However, it is still unknown whether they have a potential effect on gallstone formation.

DESIGN

To study whether the CCK-1R antagonists enhance cholelithogenesis, we investigated cholesterol crystallization, gallstone formation, hepatic lipid secretion, gallbladder emptying function and intestinal cholesterol absorption in male C57BL/6J mice treated by gavage with devazepide (4 mg/day/kg) or vehicle (as controls) twice per day and fed the lithogenic diet for 21 days.

RESULTS

During 21 days of feeding, oral administration of devazepide significantly accelerated cholesterol crystallization and crystal growth to microlithiasis, with 40% of mice forming gallstones, whereas only agglomerated cholesterol monohydrate crystals were found in mice receiving vehicle. Compared to the vehicle group, fasting and postprandial residual gallbladder volumes in response to the high-fat meal were significantly larger in the devazepide group during cholelithogenesis, showing reduced gallbladder emptying and bile stasis. Moreover, devazepide significantly increased hepatic secretion of biliary cholesterol, but not phospholipids or bile salts. The percentage of intestinal cholesterol absorption was higher in devazepide-treated mice, increasing the bioavailability of chylomicron-derived cholesterol in the liver for biliary hypersecretion into bile. These abnormalities induced supersaturated bile and rapid cholesterol crystallization.

CONCLUSIONS

The potent CCK-1R antagonist devazepide increases susceptibility to gallstone formation by impairing gallbladder emptying function, disrupting biliary cholesterol metabolism and enhancing intestinal cholesterol absorption in mice.

Special postoperative diet orders: Irrational, obsolete, and imprudent

There are no indications to prescribed special diets for postoperative patients. Low-sodium and low-fat or low-cholesterol diets are examples of restricted diets, especially in patients with heart disease and atherosclerosis. These restricted diets are unpalatable. Postoperative nausea, paralytic ileus, and vomiting caused by residual anesthetic effects and opioids used for pain control further contribute to the problem. Long-term adherence to these diets is necessary to derive benefits. Prescribing regular and palatable diets in the immediate postoperative period to meet protein and energy goals is important for wound healing and is commensurate with best clinical practices. In the following, we review the pertinent literature and offer clinical evidence that routine special diet orders for postoperative patients are not necessary.

Obesity and the risk and prognosis of gallstone disease and pancreatitis

Obesity is a risk factor for the formation of cholesterol gallstones and exposes patients to increased risk of gallstone-related complications and cholecystectomy. Rapid weight loss achieved by very low calorie diets or bariatric surgery is also a risk factor for cholelithiasis in obese patients, and therapy should take into account the higher prevalence of gallstones, the possibility of more frequent complications and the need for prophylactic treatment with oral ursodeoxycholic acid during weight loss. Obesity is also frequent in children and adolescents, and the burden of cholesterol cholelithiasis is increasing in this population. The chance to develop acute pancreatitis and the severity of the disease are higher in obese subjects because of specific pathogenic factors, including supersaturated bile and crystal formation, rapid weight loss, and visceral obesity. All health policies aimed at reducing the incidence of obesity worldwide will decrease the incidence of gallstones and gallstone-related complications. The pathophysiological scenarios and the therapeutic implications for obesity, gallstone disease, and pancreatitis are discussed.

Ursodeoxycholic acid and diets higher in fat prevent gallbladder stones during weight loss: a meta-analysis of randomized controlled trials

BACKGROUND & AIMS

The prevalence of gallstones is increasing in association with the obesity epidemic, but rapid weight loss also increases the risk of stone formation. We conducted a systematic review of the efficacy of strategies to prevent gallbladder stones in adults as they lose weight.

METHODS

Randomized controlled trials of nonsurgical strategies to prevent gallstones were identified by electronic and manual searches. Our final analysis included 13 trials, comprising 1836 participants undergoing weight loss through dieting (8 trials) or bariatric surgery (5 trials). The trials compared ursodeoxycholic acid (UDCA) or high-fat weight loss diets with control interventions. We performed random-effects meta-analyses and evaluated heterogeneity and bias with subgroup, sensitivity, regression, and sequential analysis.

RESULTS

UDCA reduced the risk of ultrasound-verified gallstones compared with control interventions (risk ratio, 0.33; 95% confidence interval [CI], 0.18-0.60; number needed to treat, 9). This effect was significantly larger in trials of diets alone (risk ratio, 0.17; 95% CI, 0.11-0.25) than in trials of patients who underwent bariatric surgery (risk ratio, 0.42; 95% CI, 0.21-0.83) (test for subgroup differences, P =.03). UDCA reduced the risk of cholecystectomy for symptomatic stones (risk ratio, 0.20; 95% CI, 0.07-0.53). Diets high in fat content also reduced gallstones, compared with those with low fat content (risk ratio, 0.09; 95% CI, 0.01-0.61). The meta-analyses were confirmed in trials with a low risk of bias but not in sequential analysis. No additional beneficial or harmful outcomes were identified.

CONCLUSIONS

On the basis of a meta-analysis of randomized controlled trials, during weight loss, UDCA and/or higher dietary fat content appear to prevent formation of gallstones.

Risk of symptomatic gallstones and cholecystectomy after a very-low-calorie diet or low-calorie diet in a commercial weight loss program: 1-year matched cohort study

Background:

Concern exists regarding gallstones as an adverse event of very-low-calorie diets (VLCDs; <800 kcal per day).

Objective:

To assess the risk of symptomatic gallstones requiring hospital care and/or cholecystectomy in a commercial weight loss program using VLCD or low-calorie diet (LCD).

Design:

A 1-year matched cohort study of consecutively enrolled adults in a commercial weight loss program conducted at 28 Swedish centers between 2006 and 2009. A 3-month weight loss phase of VLCD (500 kcal per day) or LCD (1200–1500 kcal per day) was followed by a 9-month weight maintenance phase. Matching (1:1) was performed by age, sex, body mass index, waist circumference and gallstone history (n=3320:3320). Gallstone and cholecystectomy data were retrieved from the Swedish National Patient Register.

Results:

One-year weight loss was greater in the VLCD than in the LCD group (−11.1 versus −8.1 kg; adjusted difference, −2.8 kg, 95% CI −3.1 to −2.4; P<0.001). During 6361 person–years, 48 and 14 gallstones requiring hospital care occurred in the VLCD and LCD groups, respectively, (152 versus 44/10 000 person–years; hazard ratio, 3.4, 95% CI 1.8–6.3; P<0.001; number-needed-to-harm, 92, 95% CI 63–168; P<0.001). Of the 62 gallstone events, 38 (61%) resulted in cholecystectomy (29 versus 9; hazard ratio, 3.2, 95% CI 1.5–6.8; P=0.003; number-needed-to-harm, 151, 95% CI 94–377; P<0.001). Adjusting for 3-month weight loss attenuated the hazard ratios, but the risk remained higher with VLCD than LCD for gallstones (2.5, 95% CI 1.3–5.1; P=0.009) and became borderline for cholecystectomy (2.2, 95% CI 0.9–5.2; P=0.08).

Conclusion:

The risk of symptomatic gallstones requiring hospitalization or cholecystectomy, albeit low, was 3-fold greater with VLCD than LCD during the 1-year commercial weight loss program.

Weight loss and dropout during a commercial weight-loss program including a very-low-calorie diet, a low-calorie diet, or restricted normal food: observational cohort study

BACKGROUND

The effectiveness of commercial weight-loss programs consisting of very-low-calorie diets (VLCDs) and low-calorie diets (LCDs) is unclear.

OBJECTIVE

The aim of the study was to quantify weight loss and dropout during a commercial weight-loss program in Sweden (Itrim; cost: $1300/€1000; all participants paid their own fee).

DESIGN

This observational cohort study linked commercial weight-loss data with National Health Care Registers. Weight loss was induced with a 500-kcal liquid-formula VLCD [n = 3773; BMI (in kg/m(2)): 34 ± 5 (mean ± SD); 80% women; 45 ± 12 y of age (mean ± SD)], a 1200-1500-kcal formula and food-combination LCD (n = 4588; BMI: 30 ± 4; 86% women; 50 ± 11 y of age), and a 1500-1800-kcal/d restricted normal-food diet (n = 676; BMI: 29 ± 5; 81% women; 51 ± 12 y of age). Maintenance strategies included exercise and a calorie-restricted diet. Weight loss was analyzed by using an intention-to-treat analysis (baseline substitution).

RESULTS

After 1 y, mean (±SD) weight changes were -11.4 ± 9.1 kg with the VLCD (18% dropout), -6.8 ± 6.4 kg with the LCD (23% dropout), and -5.1 ± 5.9 kg with the restricted normal-food diet (26% dropout). In an adjusted analysis, the VLCD group lost 2.8 kg (95% CI: 2.5, 3.2) and 3.8 kg (95% CI: 3.2, 4.5) more than did the LCD and restricted normal-food groups, respectively. A high baseline BMI and rapid initial weight loss were both independently associated with greater 1-y weight loss (P < 0.001). Younger age and low initial weight loss predicted an increased dropout rate (P < 0.001). Treatment of depression (OR: 1.4; 95% CI: 1.1, 1.9) and psychosis (OR: 2.6; 95% CI: 1.1, 6.3) were associated with an increased dropout rate in the VLCD group.

CONCLUSION

A commercial weight-loss program, particularly one using a VLCD, was effective at reducing body weight in self-selected, self-paying adults.

Weight loss is still an essential intervention in obesity and its complications: a review

The prevalence of obesity is more than 20% in many developed countries and it increases in developing countries. Obesity is associated with metabolic disorders, cardiovascular diseases, pulmonary diseases, digestive diseases, and cancers. Although other specific treatments for these complications exist, weight loss is still an essential intervention in obesity and its complications. Therapeutic life change, behavior modification, pharmacotherapy, and surgery are major approaches to weight loss. In addition, medicine used in diabetes such as Glucagon-like peptide-1 analogues may be a new type of medicine for obesity, at least for those obese patients with diabetes.

Risk of biliary complications in bariatric surgery

Gallstones are commonly observed after rapid weight loss, particularly after bariatric surgery. Preventive measures of gallstone formation and potential related complications are still debated. This study aimed to propose a standardized strategy according to the results of the literature. Thus, preventive measures should be determined according to patient status (evaluated clinically and by routine ultrasound) and the type of bariatric surgery. Cholecystectomy should be performed in patients with symptomatic gallstones irrespective of the planned operation, or for asymptomatic gallstones during a gastric by-pass. In other settings, ursodesoxycholic acid should be given postoperatively for 6 months.

Effects and clinical potential of very-low-calorie diets (VLCDs) in type 2 diabetes

A recent study has shown that obese patients with newly diagnosed type 2 diabetes who lose 10% of their body weight are more likely to achieve glycaemic and blood pressure targets, despite weight regain. A well-established non-surgical method for achieving weight loss >or=10% within 3 months is the use of very-low-calorie diets (VLCDs). In patients with diabetes, VLCDs are associated with rapid improvement in glycaemia and cardiovascular risk factors. The present review analyses the evidence from available trials on the effects of VLCDs on body weight, glycaemic control and complications, and their potential for clinical use in diabetes management.

The evolution of very-low-calorie diets: an update and meta-analysis

OBJECTIVE

Very-low-calorie diets (VLCDs), providing <800 kcal/d, have been used since the 1970s to induce rapid weight loss. Previous reviews of the literature have disagreed concerning the relative efficacy of VLCDs vs. conventional low-calorie diets (LCDs) for achieving long-term weight loss.

RESEARCH METHODS AND PROCEDURES

We sought to update findings on the clinical use, safety, and efficacy of VLCDs and to perform a meta-analysis of randomized trials that compared the long-term efficacy of LCDs and VLCDs. Original research articles were retrieved by a Medline search and from prior reviews of VLCDs. Trials were included only if they were randomized comparisons of LCDs and VLCDs and included a follow-up assessment at least 1 year after maximum weight loss. Data were abstracted by both authors regarding: duration of VLCD, total length of treatment, attrition, short- and long-term weight loss, changes in weight-related comorbidities, and adverse effects.

RESULTS

Six randomized trials were found that met inclusion criteria. VLCDs, compared with LCDs, induced significantly greater short-term weight losses (16.1 +/- 1.6% vs. 9.7 +/- 2.4% of initial weight, respectively; p = 0.0001) but similar long-term losses (6.3 +/- 3.2% vs. 5.0 +/- 4.0%, respectively; p > 0.2). Attrition was similar with VLCD and LCD regimens.

DISCUSSION

VLCDs did not produce greater long-term weight losses than LCDs. In the United States, the use of liquid meal replacements as part of a 1000 to 1500 kcal/d diet may provide an effective and less expensive alternative to VLCDs. In Europe, VLCDs are used with less intensive medical supervision than in the United States, which reduces the cost of this approach.

Prevalence of gallbladder stone disease in obese children and adolescents: influence of the degree of obesity, sex, and pubertal development

OBJECTIVES

The objective of the present study was to investigate the prevalence of gallbladder stone disease (GD) in a collective of obese children and adolescents and to assess the role of potential influencing factors such as the degree of obesity, sex, age, and pubertal development.

METHODS

Four hundred ninety-three obese children and adolescents (body mass index standard deviation score [BMI-SDS] > 2.0p) aged 8 to 19 years (218 males, 275 females) were included in the study and underwent ultrasound for detection of GD.

RESULTS

Gallbladder stones were detected in 10 of 493 (2.0%; 8 girls, 2 boys) subjects studied. None of the 95 prepubertal children examined were found to suffer from GD. Patients with GD were more severely obese (BMI-SDS 3.4 +/- 0.5 vs. 2.7 +/- 0.4; P < 0.001) and older (16.1 +/- 1.5 vs.13.9 +/- 2.0 years; P < 0.008) than children and adolescents without GD.

CONCLUSIONS

Compared with published data for unselected children an adolescents, the prevalence of GD (2.0%) in obese children and adolescents, previously treated with diet for obesity, is high. Obesity and female sex appear even in children and adolescents to be risk factors for the development of GD. The occurrence of prepubertal GD is rare.

Gallstone disease: Primary and secondary prevention

Several risk factors for cholesterol gallstone formation in the general population have been identified. There is a strongly increased risk of gallstone disease during prolonged fasting, rapid weight loss, total parenteral nutrition, and somatostatin(-analogue) treatment. The annual risk of biliary colic and gallstone complications in asymptomatic gallstone carriers has been investigated sparsely. In asymptomatic and symptomatic gallstone carriers, treatment with the hydrophilic bile salt ursodeoxycholic acid (UDCA) has been claimed to reduce the risk of biliary colic and gallstone complications such as acute cholecystitis and acute pancreatitis. Also, prophylactic cholecystectomy could be beneficial in certain subgroups of asymptomatic gallstone carriers. However, randomized, double-blind, placebo-controlled trials are lacking. In this review, strategies for the prevention of gallstone formation in the general population and in high-risk conditions are dealt with. Also, strategies for the prevention of biliary colic and gallstone complications in asymptomatic and symptomatic gallstone carriers are discussed.

Changes in gallbladder bile composition and crystal detection time in morbidly obese subjects after bariatric surgery

The aim of the present study was to elucidate the mechanisms of development of cholesterol crystals and gallstones during weight reduction in obese subjects. Twenty-five morbidly obese, gallstone-free subjects underwent vertical-banded gastroplasty. Gallbladder bile was collected at the time of the operation via needle aspiration and 1.1-7.3 months after the operation via ultrasound-guided transhepatic puncture of the gallbladder. The mean weight loss was 17 kg. Two patients developed gallstones and 10 patients displayed cholesterol crystals in their bile. In patients with a follow-up time of less than 2 months (n = 13), cholesterol saturation increased from 90% to 114% but tended to decrease in the patients with a follow-up time of more than 2 months. The extraction of the concanavalin-A-binding fraction from gallbladder bile obtained after weight reduction in 7 patients prolonged crystallization detection time from 6 to 10 days. The hexosamine concentration, a marker for mucin, was increased by about 100% in bile obtained in 6 of 7 patients after weight reduction. In conclusion, the results indicate that crystallization-promoting compounds (mucin) are of great importance in the development of cholesterol crystals and gallstones in obese subjects during weight reduction, probably because of defective gallbladder emptying.

Lipase inhibition by orlistat: effects on gall-bladder kinetics and cholecystokinin release in obesity

BACKGROUND

Obese subjects are at risk of developing gallstones as a result of the obese state and during weight reduction.

AIM

To study whether orlistat, by lipase inhibition, impairs gall-bladder emptying, thus further predisposing weight-losing obese subjects to gallstone formation.

METHODS

Patients entering a randomized clinical trial of 1 month of diet, followed by treatment with placebo, 3 x 60 mg orlistat or 3 x 120 mg orlistat, underwent gall-bladder emptying studies measured by ultrasound. Meal-induced cholecystokinin release and gall-bladder emptying were investigated at the start, at randomization and after 1 and 12 months.

RESULTS

One month of dieting did not change gall-bladder emptying and cholecystokinin release. After 1 month, placebo treatment resulted in a decreased fasting volume of 11%, compared with increases of 26% and 47% with 60 and 120 mg orlistat, respectively. Gall-bladder emptying increased by 9% with placebo and decreased by 15% and 53% with 60 and 120 mg orlistat, respectively. Fasting cholecystokinin values and cholecystokinin release decreased significantly in the orlistat group. After 1 year, a persistent but attenuated effect of orlistat on gall-bladder emptying and cholecystokinin release remained. Three of 40 patients developed gallstones, two on placebo with major weight loss and one on 60 mg orlistat.

CONCLUSIONS

One month of lipase inhibition by orlistat significantly impaired gall-bladder motility, which persisted to some extent after 1 year. Obese subjects with diabetes or hyperlipidaemia, who are more at risk of gallstones, should be followed carefully.

Gallstone formation prophylaxis after gastric restrictive procedures for weight loss: a randomized double-blind placebo-controlled trial

OBJECT

To determine if a 6-month regimen of prophylactic ursodeoxycholic acid is effective in the prevention of gallstones.

SUMMARY BACKGROUND DATA

Rapid weight loss after surgery for the treatment of morbid obesity is associated with a high incidence of gallstone formation.

METHODS

Patients with vertical banded gastroplasty (VBG) and adjustable gastric banding (AGB) were enrolled in this study. A single-center, randomized, double-blind, prospective trial evaluated 500 mg of ursodeoxycholic acid versus placebo, beginning within 3 days after surgery and continuing for 6 months or until gallstone development, for patients with morbid obesity. Transabdominal sonography or abdominal CT scan was obtained preoperatively at 3, 6, 12, and 24 months after surgery or until gallstone formation.

RESULTS

From March 1997 to April 2000, 262 patients were submitted to surgery. Seventy-seven patients refused to participate in the study; 43 patients with previous gallstone operation or verified gallstones preoperatively were excluded. Of 152 patients, 76 were randomized to placebo and 76 to 500 mg of ursodeoxycholic acid daily. Preoperative age, sex, weight, BMI, and postoperative weight loss were not significantly different between groups. Gallstone formation was significantly less (P = 0.0018, Fisher exact test) frequent with ursodeoxycholic acid than with placebo at 12 months, 3% versus 22%, and 8% versus 30% (P = 0.0022) at 24 months, cholecystectomy in 4.7% versus 12%, respectively (P < 0,02, Fisher exact test).

CONCLUSION

A daily dose of 500 mg of ursodeoxycholic acid for 6 months is effective prophylaxis for gallstone formation following gastric restrictive procedures.

Measurements of gallbladder motor function by ultrasonography: towards standardization

As real-time ultrasonography is a cheap, noninvasive, relatively easy, validated and reproducible technique, it can be repeated over time to document time-related changes of gallbladder motor function. Ultimately, functional ultrasonography estimates gallbladder shape and volume in fasting state and in response to a test meal (liquid or mixed solid-liquid, provided there is sufficient fat content) or exogenous stimulus (e.g., i.v. cholecystokinin or ceruletide). Although functional ultrasonography of the gallbladder has been mainly used for research purposes in specific referral centres, its simplicity makes such a technique appealing in the clinical setting to assess gallbladder motor function in both health and disease. Indications include the study of healthy subjects and of patients during pathophysiologically relevant conditions; in particular when subjects are at risk for gallbladder stasis and gallstone disease or during gallstone disease when a decision concerning medical dissolution therapy is required.

Value of measuring gallbladder motility in clinical practice

Measurement of gallbladder motility is a powerful research tool, but its value in clinical practice is uncertain. Three main conditions have been investigated for potential clinical application of this measurement. The first potential application is for identification of patients at risk of recurrence following gallstone dissolution with medical therapy. Results in this clinical setting are disappointing due to the low positive predictive value for gallstone recurrence in sluggish gallbladder emptying. The second potential application is for identification of obese patients at risk of gallstone formation during rapid weight loss. In this condition, a high negative predictive value has been reported for a normal gallbladder emptying pattern. The third potential application is for patients with recurrent biliary colic and acalcolous gallbladder disease. The diagnostic value of a provocative test involving intravenous cholecystokinin injection as a method of identifying patients likely to benefit from cholecystectomy is uncertain, partly as a consequence of non-standardized methodology. The balance of evidence reported in this review suggests a low inherent value of measurement of gallbladder motility in clinical practice. Acalcolous gallbladder disease is the clinical setting deserving further investigation on the value of the cholecystokinin provocative test, but this test needs to be standardized.

Gallbladder motility in obesity, diabetes mellitus and coeliac disease

We reviewed data on gallbladder motility in obesity, diabetes and coeliac disease. In obesity, a condition characterised by increased risk of gallstone(s), decreased gallbladder motility has heterogeneously been reported as a consequence of the different type of meals used to induce gallbladder contraction, characteristics of the population studied, technique used, and proportion of patients with hyperinsulinaemia. Moreover, recent studies have evaluated the effect of dietary restriction on gallbladder motility in obese patients. A two- to three-fold increase in the risk of cholesterol gallstone(s) has been reported in diabetic patients, mainly in relation to obesity and hypertriglyceridaemia. Furthermore, decreased gallbladder motility has been described and attributed to other factors, including underlying autonomic neuropathy, reduced gallbladder sensitivity to cholecystokinin and/or reduced number of cholecystokinin receptors on the gallbladder wall. Impaired gallbladder motility has been reported also in patients with coeliac disease in relation to reduced secretion of enteric hormones and/or decreased gallbladder sensitivity to them. In particular, untreated coeliacs, when compared to controls, showed low postprandial cholecystokinin and increased fasting somatostatin levels. Interestingly, the correlation between fasting somatostatin levels and gallbladder size has clearly been confirmed in patients affected by somatostatinoma or treated with somatostatin or its analogues. Gallbladder motility can be affected by various clinical conditions, such as obesity, diabetes mellitus and coeliac disease.

Biliary sludge: the sluggish gallbladder

Biliary sludge is a mixture of particulate matter which has precipitated from bile. It generally consists of cholesterol monohydrate crystals, calcium bilirubinate or other calcium salts. In a clinical setting, biliary sludge is almost always an ultrasonographic diagnosis. Although it is less clinically applicable, direct microscopic examination of gallbladder bile is far more sensitive than ultrasonography into sludge detection, and has to be regarded as the diagnostic gold standard. The overall prevalence of sludge in the general population is relatively low. However, several clinical conditions are associated with a particularly high prevalence of biliary sludge, including pregnancy, rapid weight loss, total parenteral nutrition, octreotide therapy, bone marrow or solid organ transplantation. The clinical course of biliary sludge varies, and complete resolution, a waxing and waning course, and progression to gallstones are all possible outcomes. It may cause complications usually associated with gallstones, such as biliary colic, acute cholecystitis, and acute pancreatitis. The main pathogenic mechanism involved in sludge formation is probably gallbladder dismotility, and in selected patients measures aimed to maintain adequate gallbladder contractions has been shown to effectively prevent sludge development.

Very low energy diets in the treatment of obesity

Very low energy diets (VLEDs) are defined as diets which contain energy levels of less than 3.4 MJ (800 kcal) per day and contain daily allowances of all essential nutritional requirements. These diets have been in clinical use for more than 20 years. They are used as the only source of nutrition for 8-16 weeks, which usually achieves a weight loss of 1.5-2.5 kg per week. Before using this type of diet a medical investigation is necessary to evaluate contraindications and to check medication use during the diet. To facilitate maintenance, cognitive behavioural counselling should always be included in a weight reduction programme using a very low energy diet. VLEDs have no serious harmful effects and can safely be used in patients with various chronic diseases. Programmes using VLEDs produce better short-term weight loss than programmes without the diet. However, in randomized controlled trials VLED-based programmes have not achieved significantly better long-term maintenance than conventional programmes. VLEDs are used when rapid weight loss is necessary because of an obesity-related disease. In other patients with obesity it is an alternative to other conservative approaches for treatment of obesity. In type 2 diabetes it may improve long-term glucose metabolism better than conventional weight reducing diets. Some studies suggest that after a VLED-based programme long-term maintenance is better among men than women. This possible gender difference is an important topic for further research.

Review: low caloric intake and gall-bladder motor function

Cholelithiasis is the primary expression of obesity in the hepatobiliary system. In obese subjects the risk of developing gallstones is increased due to a higher cholesterol saturation of gall-bladder bile. During weight reduction with very low calorie diets (VLCD) the incidence of gallstones increases, but the mechanism for gallstone formation is not completely understood and several pathogenetic mechanisms have been suggested: increased saturation of bile, increased gall-bladder secretion of mucin and calcium, increased presence of prostaglandins and arachidonic acid. Alterations in gall-bladder motility may contribute to gallstone formation, but few studies have addressed the issue of gall-bladder motility during rapid weight loss and its possible role in gallstone formation. VLCD have been associated with a gall-bladder stasis, as a consequence of reduced gall-bladder stimulation by low fat content of the diets. A threshold quantity of fat (10 g) has been documented to obtain efficient gall-bladder emptying. Ursodeoxycholic acid administered during VLCD seems to have a protective role in developing a biliary cholesterol crystals. Gall-bladder emptying was lower in response to low fat meals with respect to relative higher fat meals, before as well as during the VLCD. This may account the possibility of an adaptative response of the gall-bladder motility to a given diet regimen. Adequate fat content of the VLCD may prevent gallstone formation, maintaining adequate gall-bladder motility and may be more economic and physiologically acceptable than administration of a pharmacological agent.