Fish oil (n-3) polyunsaturated fatty acids beneficially affect biliary cholesterol nucleation time in obese women losing weight

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.

Nutritional Factors Related to Canine Gallbladder Diseases-A Scoping Review

Gallbladder mucocele, cholelithiasis, choledocholithiasis, and cholecystitis are significant contributors to morbidity and mortality in dogs. The exact etiology of these conditions remains poorly understood, though various factors, such as endocrinopathies, dyslipidemia, and impaired gallbladder motility, have been suggested as potential contributors. Surgical intervention has been described as the first choice of treatment when biliary rupture or obstruction is suspected; however, medical management may be an important part of therapeutic or preventative strategy. Reports of medical management typically involve the use of a choleretic used to stimulate the flow of bile into the duodenum or substances that act as a "hepatoprotective" agent such as S-adenosylmethionine. In people, some nutrients appear to modify bile flow and are used as agents in the prevention and treatment of these conditions in the gallbladder. This paper provides a review of the literature about possible nutritional factors involved in the pathogenesis and treatment of canine gallbladder mucocele and cholelithiasis. Opportunities for the prevention and treatment of common biliary diseases in dogs may include the reduction of dietary fat, control of hyperlipidemia with omega-3 and fiber supplementation, ensuring an adequate supply of amino acids such as methionine and tryptophan, and the evaluation of vitamins such as vitamin D.

Non-Surgical Management of Gallstones During Pregnancy: A Clinical Case Report

Gallstone disease during pregnancy, or cholelithiasis, presents significant clinical challenges due to hormonal, anatomical, and metabolic changes. Progesterone therapy, commonly used in pregnancy for uterine bleeding, can exacerbate gallstone risk by reducing gallbladder motility and promoting cholesterol gallstone formation. This case report describes a 29-year-old pregnant woman with no prior gallbladder disease who developed multiple cholesterol gallstones during the third trimester while undergoing progesterone therapy for bleeding associated with a bicornuate uterus. Conservative management during pregnancy, including dietary modifications and close monitoring, was successful, and the patient delivered a healthy infant via cesarean section. Postpartum, the patient developed obstructive jaundice, severe right hypochondriac pain, and scleral icterus due to common bile duct obstruction from gallstones. Endoscopic retrograde cholangiopancreatography (ERCP) with biliary stent placement resolved the obstruction, and pharmacological treatment with ursodeoxycholic acid (UDCA) and omega-3 fatty acids led to complete gallstone resolution within three months. Surgical intervention was avoided to prioritize postpartum recovery and breastfeeding, which resumed successfully after a brief interruption. This case highlights the value of individualized, multidisciplinary care in managing pregnancy-associated gallstone disease. Conservative approaches, including pharmacological and minimally invasive interventions, can achieve effective outcomes while minimizing maternal-fetal risks. Routine ultrasound screening in high-risk pregnancies and further investigation into UDCA and omega-3 therapies, progesterone-related gallbladder stasis, and postpartum biliary stenting protocols are recommended to optimize management strategies.

Dietary fatty acids and gallstone risk: insights from NHANES and Mendelian randomization analysis

BACKGROUND

Prior research suggests polyunsaturated fatty acids (PUFA) may prevent gallstones, but evidence on saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA) is limited. This study aims to explore the associations between fatty acids and gallstones using a large sample of American population and Mendelian randomization (MR) methods.

METHODS

The cross-sectional study involved 6,629 participants from the National Health and Nutrition Examination Survey (NHANES) 2017-2020. Logistic regression and restricted cubic spline (RCS) analysis were conducted after stratifying by gender subgroups. Two-sample MR analysis was used to explore the causal relationship between fatty acids and gallstones without confounding factors.

RESULTS

In females, higher SFA intake was positively associated with gallstone risk, while higher intake of n-3 and n-6 PUFA was negatively associated. No significant associations were found in males. No nonlinear correlations were found in any group by RCS analysis. MR analysis indicated that SFA, n-3, and n-6 PUFA could reduce gallstone risk.

CONCLUSION

The influence of dietary fatty acid composition on gallstone development differs by gender, providing insights into dietary prevention and treatment of gallstones.

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.

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.

Maternal and Postnatal Supplementation of Fish Oil Improves Metabolic Health of Mouse Male Offspring

OBJECTIVE

Over half of American women of childbearing age have either obesity or overweight. Hence, maternal programming through diet is critical for prevention of diseases in the offspring. Clinical trials with fish oil (FO) report various health benefits; however, it remains unclear whether maternal and postnatal consumption of FO protects offspring from adverse effects of consuming a high-fat (HF) diet.

METHODS

Female mice were fed HF diets supplemented without (HF) or with FO from 8 weeks before pregnancy through lactation. A low-fat (LF) diet was included as a control diet. After weaning, male offspring from HF or FO dams were either continued on their respective diet (HF-HF and FO-FO) or switched to the other diet (HF-FO and FO-HF) and compared with LF. Phenotypic and mechanistic studies were performed.

RESULTS

FO-FO offspring demonstrated significantly higher glucose clearance and insulin sensitivity compared with other pups fed the HF diet (P < 0.05). Furthermore, FO-FO pups had lower adiposity, inflammation, and fat deposition in the liver, consistent with reduced markers of hepatic lipogenesis and increased hepatic lipid oxidation.

CONCLUSIONS

Supplementation of FO during pregnancy and early life is more beneficial than treating with FO either during pregnancy or in pups.

New Aspects of Lipotoxicity in Nonalcoholic Steatohepatitis

NASH is becoming increasingly common worldwide because of the growing global prevalence of obesity and consequently NAFLD. Unfortunately, the mechanism of progression of NAFLD to NASH and then cirrhosis is not completely understood. Several factors, including insulin resistance, inflammation, oxidative stress, lipotoxicity, and bile acid (BA) toxicity, have been reported to be associated with NASH progression. The release of fatty acids from dysfunctional and insulin-resistant adipocytes results in lipotoxicity, which is caused by the ectopic accumulation of triglyceride-derived toxic metabolites and the subsequent activation of inflammatory pathways, cellular dysfunction, and lipoapoptosis. Adipose tissue (AT), especially visceral AT, comprises multiple cell populations that produce adipokines and insulin-like growth factor, plus macrophages and other immune cells that stimulate the development of lipotoxic liver disease. These biomolecules have been recently linked with many digestive diseases and gastrointestinal malignancies such as hepatocellular carcinoma. This made us question what role lipotoxicity has in the natural history of liver fibrosis. Therefore, this review focuses on the close relationship between AT and NASH. A good comprehension of the pathways that are related to dysregulated AT, metabolic dysfunction, and hepatic lipotoxicity will result in the development of prevention strategies and promising therapeutics for patients with NASH.

Risk Factors for Cholelithiasis

Gallstone disease is one of the most common public health problems in the United States. Approximately 10%-20% of the national adult populations currently carry gallstones, and gallstone prevalence is rising. In addition, nearly 750,000 cholecystectomies are performed annually in the United States; direct and indirect costs of gallbladder surgery are estimated to be $6.5 billion. Cholelithiasis is also strongly associated with gallbladder, pancreatic, and colorectal cancer occurrence. Moreover, the National Institutes of Health estimates that almost 3,000 deaths (0.12% of all deaths) per year are attributed to complications of cholelithiasis and gallbladder disease. Although extensive research has tried to identify risk factors for cholelithiasis, several studies indicate that definitive findings still remain elusive. In this review, predisposing factors for cholelithiasis are identified, the pathophysiology of gallstone disease is described, and nonsurgical preventive options are discussed. Understanding the risk factors for cholelithiasis may not only be useful in assisting nurses to provide resources and education for patients who are diagnosed with gallstones, but also in developing novel preventive measures for the disease.

Biliary Polyunsaturated Fatty Acids and Telocytes in Gallstone Disease

It has been reported that intake of ω-3 polyunsaturated fatty acids (PUFAs) reduces the risk of coronary heart disease. It also influences bile composition, decreasing biliary cholesterol saturation in the bile of patients with gallstones. In addition to bile composition disturbances, gallbladder hypomotility must be a cofactor in the pathogenesis of cholelithiasis, as it leads to the prolonged nucleation phase. Our current knowledge about gallbladder motility has been enhanced by the study of a population of newly described interstitial (stromal) cells-telocytes (TCs). The purpose of this study was to determine whether TC loss, reported by our team recently, might be related to bile lithogenicity, expressed as cholesterol saturation index or the difference in biliary PUFA profiles in patients who suffer from cholecystolithiasis and those not affected by this disease. We determined biliary lipid composition including the fatty acid composition of the phospholipid species in bile. Thus, we investigated whether differences in biliary fatty acid profiles (ω-3 PUFA and ω-6 PUFA) in gallbladder bile may influence its lithogenicity and the quantity of TCs within the gallbladder wall. We conclude that the altered PUFA concentrations in the gallbladder bile, with elevation of ω-6 PUFA, constitute important factors influencing TC density in the gallbladder wall, being one of the possible pathophysiological components for the gallstone disease development. This study established that altered bile composition in patients with cholelithiasis may influence TC quantity within the gallbladder muscle, and we concluded that reduction in TC number may be a consequence of the supersaturated bile toxicity, while some other bile components (ω-3 PUFA, glycocholic, and taurocholic acids) may exert protective effects on TC and thus possibly influence the mechanisms regulating gallbladder and extrahepatic bile duct motility. Thus, ω-3 PUFA may represent a possible option to prevent formation of cholesterol gallstones.

Preventing a Mass Disease: The Case of Gallstones Disease: Role and Competence for Family Physicians

Gallstone formation is the result of a complex interaction between genetic and nongenetic factors. We searched and reviewed the available literature to define how the primary prevention of gallstones (cholesterol gallstones in particular) could be applied in general practice. Electronic bibliographical databases were searched. Prospective and retrospective cohort studies and case-controlled studies were analyzed and graded for evidence quality. The epidemiological data confirmed that genetic factors are estimated to account for only approximately 25% of the overall risk of gallstones, while metabolic/environmental factors are at least partially modifiable in stone-free risk groups, and are thus modifiable by primary prevention measures related to diet, lifestyle, and environmental factors (i.e., rapid weight loss, bariatric surgery, somatostatin or analogues therapy, transient gallbladder stasis, and hormone therapy). There is no specific recommendation for the secondary prevention of recurrent gallstones. Family physicians can contribute to preventing gallstones due to their capability to identify and effectively manage several risk factors discussed in this study. Although further studies are needed to better elucidate the involvement of epigenetic factors that may regulate the effect of environment and lifestyle on gene expression in the primary prevention of gallstone formation, preventive interventions are feasible and advisable in the general practice setting.

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.

Does Fish Oil Have an Anti-Obesity Effect in Overweight/Obese Adults? A Meta-Analysis of Randomized Controlled Trials

Context

Accumulating evidence has suggested favorable effects of fish oil on weight loss in animal experiments; however, findings remain inconsistent in humans.

Objects

The meta-analysis was performed to investigate the influence of fish oil on some parameters of body composition in overweight/obese adults.

Design

Human randomized, placebo-controlled trials were identified by a systematic search of Embase, PubMed, the Cochrane Library, web of science and reference lists of related reviews and articles. The random-effects model was used to estimate the calculated results.

Results

In total, 21 studies with 30 study arms were included in this analysis. Calculated results of the meta-analysis demonstrated that fish oil had no effect on reducing body weight (overall SMD = -0.07, 95% CI -0.21 to 0.07, P = 0.31) and BMI (overall SMD = -0.09, 95% CI -0.22 to 0.03, P = 0.14) whether alone or combined with life modification intervention in overweight/obese subjects. However, waist circumference was significantly reduced (SMD = -0.23, 95% CI -0.40 to -0.06, P = 0.008) in those with fish oil supplementation combined with life modification intervention. Waist hip ratio (WHR) was significantly reduced (overall SMD = -0.52 95% CI -0.76 to -0.27, P < 0.0005) in fish oil supplemented individuals with or without combination life modification intervention.

Conclusion

Current evidence cannot support an exact anti-obesity role of n-3 polyunsaturated fatty acids (PUFAs) in overweight/obese subjects. However, these subjects may benefit from reducing abdominal fat with fish oil supplementation especially when combined with life modification intervention. Further large-scale and long-term clinical trials are needed to gain definite conclusions.

Management of gallstones and its related complications

The majority of gallstone patients remain asymptomatic; however, interest toward the gallstone disease is continuing because of the high worldwide prevalence and management costs and the development of gallstone symptoms and complications. For cholesterol gallstone disease, moreover, a strong link exists between this disease and highly prevalent metabolic disorders such as obesity, dyslipidemia, type 2 diabetes, hyperinsulinemia, hypertriglyceridemia and the metabolic syndrome. Information on the natural history as well as the diagnostic, surgical (mainly laparoscopic cholecystectomy) and medical tools available to facilitate adequate management of cholelithiasis and its complications are, therefore, crucial to prevent the negative outcomes of gallstone disease. Moreover, some risk factors for gallstone disease are modifiable and some preventive strategies have become necessary to reduce the onset and the severity of complications.

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.

Statins as potential treatment for cholesterol gallstones: an attempt to understand the underlying mechanism of actions

INTRODUCTION

Statin therapy is widely used across the globe for the treatment and prevention of cardiovascular disease (CVD). It is well established that statin therapy is associated with significant decreases in low-density lipoprotein cholesterol (LDL-C) and plasma cholesterol levels. Cholesterol gallstones are a common problem, resulting in hospital admission and surgery, throughout western healthcare systems.

AREAS COVERED

This review describes the mechanisms, and addresses the potential, for statins to be used as a treatment for gallstones. Medline was searched for the risk factors and treatment of cholesterol gallstones.

EXPERT OPINION

Obesity, metabolic syndrome, non-alcoholic fatty liver disease (NAFLD), insulin resistance and high-fat diets (unsaturated fats) rich in cholesterol are all associated risk factors for cholesterol gallstones. In view of the high prevalence of cholesterol gallstones, there is an urgent need to understand whether pharmacological therapies can be harnessed for the treatment of cholesterol gallstones. Gallstones are shown to be associated with an increased risk, not only of mortality, but also of CVD. Statins, widely used in prevention of CVD and hypercholesteremia, have been shown to dissolve cholesterol gallstones in animal models and human studies, highlighting the potential for a pharmacological therapy for gallstones. More studies are required to understand the role of statins in the treatment of gallstones and for comparison with current treatment strategies.

Role of diet in cholesterol gallstone formation

BACKGROUND

There is a high prevalence of gallstone disease in Western countries as a consequence of genetic, biochemical, and environmental factors. Animal and clinical studies have explored the importance of dietary elements. Overwhelming but conflicting information has been reported about the relationship between specific dietary components and gallstone disease. Although the detailed biochemical pathways have been described in experimental models, human studies are mainly epidemiological.

METHODS

We performed a Medline search with the terms "diet", "gallstones", "cholesterol", "risk factors", including results from 1965 to 2006 and the author's personal library to review the relationship between dietary factors and cholesterol gallstone disease.

RESULTS

We identified over 150 references and present their results with respect to the author's criteria.

CONCLUSIONS

The best delineated relationship between cholesterol gallstones and diet was found in the studies that analyzed total calorie intake, refined sugars and fiber. The possible mechanisms are discussed in base of experimental studies.

Low serum levels of ghrelin are associated with gallstone disease

AIM

To explore the role of ghrelin in gallstone disease.

METHODS

We carried out a cross-sectional study in 150 subjects, 38 with gallstones (cases) and 112 controls. We also did a real-time PCR-RT study in twenty gallbladder samples each. Body mass index (BMI), serum insulin, ghrelin, and serum lipids were measured. Logistic regression analyses (univariate and multivariate) were conducted to estimate the probability of gallstone disease associated with serum ghrelin concentrations.

RESULTS

Cases were statistically different from controls in gender distribution (P = 0.01), age (53 vs 44 yr, P = 0.002), BMI (28 vs 25; P = 0.004), and glucose (5.26 vs 4.98 mmol/L; P = 0.05). The prevalence of ghrelin serum levels above the third tercile was lower in subjects without metabolic syndrome (P < 0.05). In a multivariate model, we found a protective effect, when ghrelin values were higher than the median value (OR = 0.27, 95%CI 0.09-0.82, P = 0.02). Twenty (20%) gallbladder specimens expressed ghrelin mRNA.

CONCLUSION

Serum ghrelin concentrations are associated with a protective effect of GD.

Spray-dried milk supplemented with alpha-linolenic acid or eicosapentaenoic acid and docosahexaenoic acid decreases HMG Co A reductase activity and increases biliary secretion of lipids in rats

In our earlier study, we have shown that rats fed spray-dried milk containing alpha-linolenic acid (LNA 18:3 n-3) or eicosapentaenoic acid (EPA 20:5 n-3) and docosahexaenoic acid (DHA 22:6 n-3) had significantly lower amounts of serum and liver cholesterol. To evaluate the mechanism for hypocholesterolemic effect of n-3 fatty acids containing milk formulation, we fed male Wistar rats with spray-dried milk containing linseed oil (LSO) (source of LNA) or fish oil (FO) (source of EPA+DHA) for 8 weeks. Feeding n-3 fatty acid containing milk formulation lowered the hepatic 3-hydroxy-methylglutaryl coenzyme A (HMG Co A) activity by 17-22% compared to rats given control diet devoid of n-3 fatty acids. The cholesterol level in liver microsomes was found to be decreased by 16% and 20%, respectively, in LSO and FO containing formulation fed rats. The bile flow was enhanced to an extent of 19-23% in experimental groups compared to control animals. The biliary cholesterol and phospholipid secretion was increased to an extent of 49-55% and 140-146%, respectively, in rats fed n-3 fatty acid containing formulation. The increase in the total bile acids secretion in bile was mainly reflected on an increase in the levels of taurine conjugated bile acids. These results indicated that n-3 fatty acid containing spray-dried milk formulation would bring about the hypocholesterolemic effect by lowering HMG Co A reductase activity in liver and by increasing the secretion of bile constituents.

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.

Diet as a risk factor for cholesterol gallstone disease

Cholesterol gallstone disease is a common condition in western populations. The etiology is multifactorial with interaction of genetic and environmental factors. Obesity, aging, estrogen treatment, pregnancy and diabetes are consistently associated to a higher risk. A number of dietary factors have been involved in the pathogenesis of cholelithiasis. In this article we summarize several studies that have evaluated the role of diet as a potential risk factor for gallstone formation, including energy intake, cholesterol, fatty acids, fiber, carbohydrates, vitamins and minerals, and alcohol intake. Consumption of simple sugars and saturated fat has been mostly associated to a higher risk, while fiber intake and moderate consumption of alcohol, consistently reduce the risk. The association between cholesterol intake and gallstone disease has been variable in different studies. The effects of other dietary factors are less conclusive; additional studies are therefore necessary to clarify their relevance in the pathogenesis of gallstone disease. Recent discoveries of the role of orphan nuclear receptors in the regulation of fatty acid and hepatic cholesterol metabolism and excretion open new perspectives for a better understanding of the role of dietary constituents on cholesterol gallstone formation. KEY TEACHING POINTS: The etiology of cholesterol gallstone disease is multifactorial with interaction between genome and environment. It has been postulated that dietary constituents are important determinants for the formation of lithogenic bile. Intake of high energy, simple sugar and saturated fat favors gallstone formation. Fiber and moderate consumption of alcohol reduce the risk. The role of orphan nuclear receptors in the regulation of hepatic cholesterol metabolism and excretion open new leads for understanding the role of dietary constituents on cholesterol gallstone formation.

Prevention or surgical treatment of gallstones in patients undergoing gastric bypass surgery for obesity

It is well known that obesity is a risk for gallstone formation and biliary sludge. Additionally, it has been clearly shown that rapid weight loss following bariatric surgery is a risk factor for cholesterol cholelithiasis. Multiple serious complications from gallstones such as cholecystitis, cholangitis, gallstone pancreatitis, and cholecystenteric fistulae may occur. Thus, it is necessary to employ medical or surgical methods to prevent or treat gallstones in this group. Therapy should be individualized. Although there is a high incidence of gallstones in this group, only a minority of individuals will develop symptomatic disease. When used in patients who are compliant, ursodeoxycholic acid therapy can be effective to prevent gallstone formation during rapid weight loss. The cost effectiveness of routine ursodeoxycholic acid therapy compared with the potential costs of complicated gallstone disease needs to be further investigated. Combined cholecystectomy with Roux-en-Y gastric bypass surgery is a safe and appropriate therapeutic option in those with preoperatively known gallstones, biliary sludge, and prior episodes of cholecystitis. However, routine cholecystectomy at the time of gastric bypass surgery is not warranted for all patients because of the increased time of operation and postoperative hospitalization, as well as all the potential complications after cholecystectomy. The approach of routine cholecystectomy in this setting subjects many patients to an unnecessary procedure because the majority will not develop symptoms or complications of gallstones. Furthermore, cholecystectomy is technically easier to perform after weight loss occurs.

Short term effects of dietary medium-chain fatty acids and n-3 long-chain polyunsaturated fatty acids on the fat metabolism of healthy volunteers

BACKGROUND

The amount and quality of dietary fatty acids can modulate the fat metabolism.

OBJECTIVE

This dietary intervention is based on the different metabolic pathways of long-chain saturated fatty acids (LCFA), which are mostly stored in adipocytic triacylglycerols, medium-chain fatty acids (MCFA) which are preferentially available for hepatic mitochondrial beta-oxidation and n-3 long-chain polyunsaturated fatty acids (n-3 LCPUFA) suggested to modulate fat oxidation and storage by stimulating the peroxisomal beta-oxidation. Combined dietary MCFA and n-3 LCPUFA without LCFA may synergistically stimulate fatty acid oxidation resulting in blood lipid clearance and LCFA release from adipocytes.

DESIGN

In a short term, parallel, randomized, double-blind trial effects on the fatty acid metabolism of 10 healthy volunteers (Body Mass Index 25-30) of a formula containing 72% MCFA and 22% n-3 LCPUFA without LCFA (intake: 1.500 kcal/day; fat: 55.5% of energy) were measured in comparison to an isoenergetic formula with equal fat amount and LCFA dominated lipid profile.

RESULTS

The plasma triacylglycerol (p < 0.1) and cholesterol (p < 0.05) content decreased in the test group. The n-3/n-6 LCPUFA (> or = C 20) ratio increased (p < 0.0001) after 4 days treatment. The LCFA content was similar in both groups despite missing LCFA in the test formula indicating LCFA release from adipocytes into the plasma. Both groups significantly reduced body weight considerably 4 kg (p < 0.01) and fat mass up to 50% of weight loss (p < 0.05).

CONCLUSION

Combined dietary 72% MCFA and 22% n-3 LCPUFA without LCFA stimulate the fatty acid oxidation and release from adipocytes without affecting any safety parameters measured.

Plasma leptin and the cholesterol saturation of bile are correlated in obese women after weight loss

Increased cholesterol secretion is a major alteration of biliary function in obese subjects Leptin is a regulator of food intake and is increased in plasma of subjects with low energy expenditure and high adiposity. We investigated the relationship between leptin and the cholesterol saturation of bile in obese women before and after weight reduction by energy restriction (5.02 MJ/d). We studied women (n = 14) with a body mass index (BMI) > or = 30 kg/m(2) who were 35.4 +/- 2.3 y old and who did not have a history of gallstones. They were studied by ultrasound to ensure absence of stones or sludge. BMI, gallbladder bile composition, plasma leptin, serum lipids and lipoproteins cholesterol levels were recorded at baseline and after 6 wk of weight reduction. There were decreases in BMI (33.9 +/- 3.1 to 31.1 +/- 3.6 kg/m(2), P < 0.0001) and leptin levels (16.7 +/- 9.7 to 10.0 +/- 6.7 micro mol/L, P < 0.05) during weight loss. After the experimental period, there were positive correlations between plasma leptin levels and BMI (r = 0.71, P < 0.004); leptin levels and the cholesterol saturation index (CSI) (r = 0.53, P < 0.05); the CSI and LDL cholesterol (r = 0.73, P < 0.003); and negative correlations between leptin levels and HDL cholesterol (r = -0.54, P < 0.05) and LDL cholesterol (r = -0.57, P < 0.03). We have shown relationships among HDL cholesterol, CSI and leptin. This could be useful in understanding the pathophysiology of cholesterol gallstone formation in obese people.