A nested case-control study on dietary fat consumption and the risk for gallstone disease

Mendelian randomization study on the causal relationship between food and cholelithiasis

Background

Cholelithiasis, commonly referred to as gallstones, is a prevalent medical condition influenced by a combination of genetic factors, lifestyle choices, and dietary habits. Specific food items have been associated with an increased susceptibility to cholelithiasis, whereas others seem to offer a protective effect against its development.

Methods

In this study, we conducted a Mendelian randomization (MR) analysis using a large-scale genetic dataset comprising individuals with European ancestry to explore the potential causal relationship between diet and cholelithiasis. The analysis incorporated 17 food-related variables, which were considered as potential factors influencing the occurrence of this condition.

Results

Our findings indicate that a higher consumption of cooked vegetables, dried fruit, and oily fish is associated with a reduced risk of cholelithiasis. Conversely, a higher consumption of lamb is associated with an increased risk of developing the condition. Importantly, these associations proved robust to sensitivity and heterogeneity tests, and the pleiotropic test results further supported the hypothesis of a causal relationship between diet and cholelithiasis.

Conclusion

Through our study, we provide compelling evidence for the existence of a causal relationship between diet and cholelithiasis. Adopting a dietary pattern enriched with cooked vegetables, dried fruit, and oily fish, while minimizing lamb intake, may contribute to the prevention of cholelithiasis. Recognizing diet as a modifiable risk factor in the prevention and management of this condition is of paramount importance, and our study offers valuable insights in this regard.

Associations of fatty acids with the risk of biliary tract calculus and inflammation: a Mendelian randomization study

BACKGROUND

The presence of gallstones in both the gallbladder and bile ducts is referred to as cholelithiasis. The prevalence of cholecystolithiasis and bile duct stones differs. Observational and Mendelian randomization (MR) studies have elucidated the significant contributing role of numerous fatty acids (FAs) in the development of cholelithiasis. Despite numerous studies about cholelithiasis, evidence on the relationship between serum FA levels and cholecystolithiasis, as well as bile duct stones with or without inflammation, remains insufficient.

METHODS

A two-sample MR study was designed to clarify the impact of serum FA levels on various bile duct inflammatory diseases. The summary statistics of single nucleotide polymorphisms (SNPs) associated with fatty acids were obtained from the UK Biobank (UKB) and included data from 114,999 participants. The researchers obtained GWAS summary statistics for cholecystolithiasis and bile duct stones in 463,010 and 361,194 European participants, including cases with and without inflammation. No sample overlap between the exposure and outcome was verified through the "mr-lap" package. The SNPs were screened to identify instrumental variables (IVs). Cochran's Q test was applied for heterogeneity assessment. Inverse variance weighting (IVW) (fixed effects or random effects), MR-Egger regression and weighted median methods were used for MR. Multivariable MR was applied to determine the direct effect of each exposure on the outcome. A false discovery rate (FDR) was applied to adjust for multiple testing correction based on the Benjamini-Hochberg method. Finally, the FinnGen Consortium was used to validate some results.

RESULTS

The overall concentration of polyunsaturated fatty acids (PUFAs) in the serum was negatively associated with the risk of calculus of the gallbladder with acute cholecystitis (IVW, OR = 0.996, P = 0.038, CI 0.992-0.999; weighted median, OR = 0.995, P = 0.025, CI 0.991-0.999). The percentage of PUFAs to total monounsaturated fatty acids(MUFAs) (IVW, OR = 0.998, P = 0.045, CI 0.997-0.999) and the percentage of PUFAs to total FAs (IVW, OR = 0.997, P = 0.025, CI 0.995-0.999) had a protective role against cholecystitis. The percentage of PUFAs to total FAs had a protective role against calculus of the gallbladder without cholecystitis (IVW, OR = 0.995, P = 0.026, CI 0.990-0.999; MR Egger, OR = 0.99, P = 0.03, CI 0.982-0.998; weighted median, OR = 0.991, P = 5.41e-06, CI 0.988-0.995). Conversely, the percentage of MUFAs to total FAs increased the risk for cholecystitis (IVW, OR = 1.001, P = 0.034, CI 1.0001-1.002). However, there were no causal effects of the above exposures on the outcomes through multivariable MR and multiple testing correction. Finally, the causal effects of the above exposures on cholecystitis were validated in the FinnGen Consortium, which suggested that the percentage of PUFAs to total FAs (IVW, OR = 0.744, P = 0.021, CI 0.579-0.957) had a protective role against cholecystitis.

CONCLUSION

These Mendelian randomization findings suggested that more attention should be focused on people who have low serum PUFA levels, which may have a potential role in the occurrence of calculus of the gallbladder or cholecystitis rather than calculus of the bile duct without cholangitis or cholecystitis.

Evaluation of homocysteine, vitamin, and trace element levels in women with gallstones

OBJECTIVE

It was aimed to examine the changes in homocysteine, folic acid, and vitamin B12, which metabolize homocysteine from the body, and trace elements (zinc, copper, selenium, nickel) that affect the structure of tissues and epithelium in female patients with gallstone disease. Moreover, it was aimed to investigate the contribution of these selected parameters to the etiology of the disease and their usability in treatment according to the findings obtained.

MATERIALS AND METHODS

Eighty patients, including 40 female patients (Group I) and 40 completely healthy female individuals (Group II) were included in this study. Serum homocysteine, vitamin B12, folate, zinc, copper, selenium, and nickel levels were evaluated. Electrochemiluminescence immunoassay was used in the analysis of vitamin B12, folic acid, and homocysteine levels, and the ICP-MS method was used in the analysis of trace element levels.

RESULTS

Homocysteine levels in Group I were statistically significantly higher than in Group II. In terms of vitamin B12, zinc, and selenium, Group I levels were found to be statistically significantly lower than group II. There was no statistically significant difference between Group I levels and Group II in terms of copper, nickel, and folate.

CONCLUSION

It was suggested that homocysteine, vitamin B12, zinc, and selenium levels should be determined in patients with gallstone disease and that vitamin B12, which is especially important in the excretion of homocysteine from the body, and zinc and selenium, which prevent the free radical formation and protect from its effects, should be added to the diets of these patients.

Identification of blood metabolites linked to the risk of cholelithiasis: a comprehensive Mendelian randomization study

BACKGROUND AND AIMS

Observational and Mendelian randomization (MR) studies have identified several modifiable risk factors of cholelithiasis. However, there is limited evidence about the causal effect of blood metabolites on the cholelithiasis risk.

METHODS

To have a comprehensive understanding to causal relations between blood metabolites and cholelithiasis, for the primary discovery, we applied two MR methods to explore the associations between 249 circulating metabolites and cholelithiasis. For secondary validations, we replicated the examinations using another metabolic dataset with 123 metabolites. The summary statistics of cholelithiasis were retrieved from FinnGen Consortium Release 5 and UK Biobank. Inverse-variance weighted, weight median and MR-egger methods were used for calculating causal estimates. Furthermore, Bayesian model averaging MR (MR-BMA) method was employed to detect the dominant causal metabolic traits with adjustment for pleiotropy effects.

RESULTS

In the primary analysis, sphingomyelin showed consistent protective causal associations with cholelithiasis; while plasma cholesterol-associated traits showed generally inverse correlation with cholelithiasis risk. Notably, large numbers of traits within the (un)saturated fatty acid category demonstrated significant causal effects. Secondary analyses demonstrated similar results, with traits related to the levels of bisallylic groups in fatty acids showing protective effects. Lastly, MR-BMA analyses discovered that the degree of unsaturation plays a predominant role in reducing the risk of cholelithiasis.

CONCLUSION

Our MR study provides a complete atlas of associations between plasma metabolites on cholelithiasis risk. It highlighted that genetically predicted sphingomyelin and degree of unsaturation of fatty acid were causally associated with the reduced risk of cholelithiasis.

Systematic Review: Impact of Social Determinants of Health on the Management and Prognosis of Gallstone Disease

Background:

Due to its prevalence, gallstone disease is a major public health issue. It affects diverse patient populations across various socioeconomic levels. Socioeconomic and geographic deprivation may impact both morbidity and mortality associated with digestive diseases, such as biliary tract disease.

Aim:

The aim of this systematic review was to review the available data on the impact of socioeconomic determinants and geographic factors on gallstone disease and its complications.

Methods:

This systematic review was conducted following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The MEDLINE and Web of Science databases were searched by two investigators to retrieve studies about the impact of income, insurance status, hospital status, education level, living areas, and deprivation indices on gallstone disease. Thirty-seven studies were selected for this review.

Results:

Socially disadvantaged populations appear to be more frequently affected by complicated or severe forms of gallstone disease. The prognosis of biliary tract disease is poor in these populations regardless of patient status, and increased morbidity and mortality were observed for acute cholangitis or subsequent cholecystectomy. Limited or delayed access and low-quality therapeutic interventions could be among the potential causes for this poor prognosis.

Conclusions:

This systematic review suggests that socioeconomic determinants impact the management of gallstone disease. Enhanced knowledge of these parameters could contribute to improved public health policies to manage these diseases.

Association between omega-3/6 fatty acids and cholelithiasis: A mendelian randomization study

Background

Omega-3 and omega-6 may be protective factors for cholelithiasis. However, this relationship has not yet been demonstrated clearly. Therefore, we attempted to identify these causal relationships.

Materials and methods

The omega-3/6 fatty acid discovery dataset was obtained from UK Biobank and contained 114,999 individuals. The validation set was derived from an independent genome-wide association study (GWAS) and contained 13,544 individuals. The cholelithiasis dataset was derived from FinnGen and contained 19,023 cases and 195,144 controls. The inverse variance weighting (IVW) method was used as the main method of analysis in this study. Multiple methods of analysis were also used in the repeated methods, including the MR-Egger, weighted median, MR-pleiotropic residual sum (MR-PRESSO), outliers, and maximum likelihood methods. In addition, we used multiple sensitivity analyses to identify the potential pleiotropy.

Result

In the discovery stage, the results of the random effect IVW analysis showed that higher omega-3 levels were correlated inversely with the risk of cholelithiasis (β = -0.22, 95% CI [-0.32 to -0.12], P = 1.49 × 10^-5). When the replication analysis was performed using another set of instrumental variables (IVs), the causal relationship between omega-3 fatty acids and cholelithiasis remained stable (β = -0.42, 95% CI [-0.66 to -0.18], P = 5.49 × 10^-4), except for the results obtained using the MR-Egger method, which were not significant. The results of the IVW approach showed that each SD increase in omega-6 levels was associated negatively with the risk of cholelithiasis, both in the discovery (β = -0.21, 95% CI [-0.35 to -0.06], P = 4.37 × 10^-3) and the validation phases (β = -0.21, 95% CI [-0.40 to -0.02], P = 3.44 × 10^-2).

Conclusion

The results of our MR study suggest that omega-3/6 is associated with cholelithiasis risk. Attention to the risk of cholelithiasis in individuals with low serum omega-3/6 levels is necessary.

Structure and Function of Hepatobiliary ATP Binding Cassette Transporters

The liver is beyond any doubt the most important metabolic organ of the human body. This function requires an intensive crosstalk within liver cellular structures, but also with other organs. Membrane transport proteins are therefore of upmost importance as they represent the sensors and mediators that shuttle signals from outside to the inside of liver cells and/or vice versa. In this review, we summarize the known literature of liver transport proteins with a clear emphasis on functional and structural information on ATP binding cassette (ABC) transporters, which are expressed in the human liver. These primary active membrane transporters form one of the largest families of membrane proteins. In the liver, they play an essential role in for example bile formation or xenobiotic export. Our review provides a state of the art and comprehensive summary of the current knowledge of hepatobiliary ABC transporters. Clearly, our knowledge has improved with a breath-taking speed over the last few years and will expand further. Thus, this review will provide the status quo and will lay the foundation for new and exciting avenues in liver membrane transporter research.

Association of Body Mass Index and Diet with Symptomatic Gall Stone Disease: A Case-Control Study

BACKGROUND

Gall stone disease (GSD) is one of the commonest gastrointestinal disorders. Causative factors can be non-modifiable as genetics and modifiable like dietary habits. High-fat diet and high BMI are well known contributing factors world-over. Local and regional data is deficient about these factors. Moreover, Indo-Pakistani dietary patterns are very different from the western population. This study was conducted to see the association of high BMI and diet with GSD in our population.

MATERIALS AND METHODS

This case-control study was conducted in Shifa International Hospital, Islamabad, from 2012 to 2017. We included all female patients above 25 years of age with symptomatic gall stones on ultrasonography as cases and all females above 25 years of age with no gall stones on ultrasonography (done for any reason) as controls. The patients with gall stones having some other clear predisposing cause for gallstone formation, e.g., stoma, sudden weight loss, etc. were excluded. BMI, demographic details, dietary habits, and clinical profile of cases and controls were recorded. Data were analyzed by SPSS v 21. p-values were calculated.

RESULTS

A total of 396 patients were included in this study, with 103 cases and 293 controls. The mean BMI of GSD cases was 27.576±5.753, while controls had a mean BMI of 25.638±7.008 (p=0.08). About 26.4% of cases had an average fat consumption greater than 100g/day as compared to 11.9% controls (p=0.035). The average red meat intake per week was 222g among cases while 210g among controls (p=0.001). The average intake of fried food per week was 270g among controls and 250g among cases (p=0.012). The average intake of bakery items per week was 240g among cases and 210g among controls (p=0.038).

CONCLUSION

Gall stone disease is significantly related to high BMI and high dietary fat and meat intake in our population.

Cholesterol cholelithiasis: part of a systemic metabolic disease, prone to primary prevention

Cholesterol gallstone disease have relationships with various conditions linked with insulin resistance, but also with heart disease, atherosclerosis, and cancer. These associations derive from mechanisms active at a local (i.e. gallbladder, bile) and a systemic level and are involved in inflammation, hormones, nuclear receptors, signaling molecules, epigenetic modulation of gene expression, and gut microbiota. Despite advanced knowledge of these pathways, the available therapeutic options for symptomatic gallstone patients remain limited. Therapy includes oral litholysis by the bile acid ursodeoxycholic acid (UDCA) in a small subgroup of patients at high risk of postdissolution recurrence, or laparoscopic cholecystectomy, which is the therapeutic radical gold standard treatment. Cholecystectomy, however, may not be a neutral event, and potentially generates health problems, including the metabolic syndrome. Areas covered: Several studies on risk factors and pathogenesis of cholesterol gallstone disease, acting at a systemic level have been reviewed through a PubMed search. Authors have focused on primary prevention and novel potential therapeutic strategies. Expert commentary: The ultimate goal appears to target the manageable systemic mechanisms responsible for gallstone occurrence, pointing to primary prevention measures. Changes must target lifestyles, as well as experimenting innovative pharmacological tools in subgroups of patients at high risk of developing gallstones.

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.

An update on the pathogenesis of cholesterol gallstone disease

PURPOSE OF REVIEW

Gallstone disease is a major epidemiologic and economic burden worldwide, and the most frequent form is cholesterol gallstone disease.

RECENT FINDINGS

Major pathogenetic factors for cholesterol gallstones include a genetic background, hepatic hypersecretion of cholesterol, and supersaturated bile which give life to precipitating cholesterol crystals that accumulate and grow in a sluggish gallbladder. Additional factors include mucin and inflammatory changes in the gallbladder, slow intestinal motility, increased intestinal absorption of cholesterol, and altered gut microbiota. Mechanisms of disease are linked with insulin resistance, obesity, the metabolic syndrome, and type 2 diabetes. The role of nuclear receptors, signaling pathways, gut microbiota, and epigenome are being actively investigated.

SUMMARY

Ongoing research on cholesterol gallstone disease is intensively investigating several pathogenic mechanisms, associated metabolic disorders, new therapeutic approaches, and novel strategies for primary prevention, including lifestyles.

Association between diet and gallstones of cholesterol and pigment among patients with cholecystectomy: a case-control study in Korea

BACKGROUND

The prevalence of cholesterol gallstones is high in Western populations, while pigment gallstones are common in Asian populations. Dietary factors are suggested to be associated with gallstone risk, but their relationship with gallstone type has not been evaluated. This study investigated the association between diet and risk of cholesterol gallstone or pigment gallstone in a Korean population whose dietary pattern and type of gallstone were changed during the last 30 years.

METHODS

Patients with cholesterol (n = 40) and pigment (n = 59) gallstones were recruited after laparoscopic cholecystectomy and were compared with those of age- and sex-matched controls without gallstones (n = 99). Dietary intakes were assessed by trained dietitians using a semi-quantitative food frequency questionnaire. Multinomial logistic regression analysis was performed to calculate odds ratios and 95% confidence intervals to examine the associations between diet and risk for type of gallstones adjusted by potential confounders.

RESULTS

Patients with cholesterol gallstone consumed more lipid, animal lipid, beef, pork, and fried food than those with pigment gallstones and control, while patients with pigment gallstone consumed more carbohydrate and noodles than patients with cholesterol gallstone and control. In multinomial logistic regression analysis using control as reference group, dietary pattern with high consumption of beef, pork, and fried food was associated with risk of cholesterol gallstones, while there was no association between the risk of pigment gallstone and dietary pattern. In addition, control consumed more alcohol than patients with cholesterol and pigment gallstones.

CONCLUSIONS

The present study suggested consumption of fat from meat and fried foods increased the risk of cholesterol gallstone, and intake of carbohydrate from noodles increased the risk of pigment gallstone.

Diet and Risk of Cholecystectomy: A Prospective Study Based on the French E3N Cohort

OBJECTIVES

This study aimed to examine the relationship between diet and cholecystectomy risk, using three approaches, in a large French cohort.

METHODS

In a prospective cohort study in French women who completed a food-frequency questionnaire at baseline, we analyzed diet with three approaches: food groups, dietary patterns obtained by factor analysis, and the Mediterranean diet score. The primary outcome was cholecystectomy. We used Cox proportional hazards regression to assess the relationship between diet and cholecystectomy risk, adjusting for the main potential confounders.

RESULTS

During 1,033,955 person years of follow-up, we identified 2,778 incident cases of cholecystectomy. Higher intakes of legumes, fruit, vegetable oil, and wholemeal bread were associated with decreased cholecystectomy risk. Two dietary patterns were identified by factor analysis: "Western" (essentially processed meat, pizza, pies, high-alcohol beverages, French fries, sandwiches…) and "Mediterranean" (essentially fruits, vegetables, seafood, and olive oil). The "Mediterranean" pattern was inversely associated with cholecystectomy risk in the subgroup of postmenopausal women who ever used menopausal hormone therapy (hazard ratio for quartile 4 vs. 1=0.79, 95% confidence interval (CI): 0.65-0.95; P for linear trend=0.008). High adherence to the Mediterranean diet was associated with decreased risk of cholecystectomy (hazard ratio for a 6-9 score vs. 0-3=0.89, 95% CI: 0.80-0.99; P for linear trend=0.02).

CONCLUSIONS

Adherence to a diet rich in fruit, vegetables, legumes, and olive oil was associated with a reduction in cholecystectomy risk in French women. Further studies in different settings are requested.