The Prevalence of Lean/Nonobese Nonalcoholic Fatty Liver Disease: A Systematic Review and Meta-Analysis

LASSO-derived model for the prediction of lean-non-alcoholic fatty liver disease in examinees attending a routine health check-up

BACKGROUND

Lean individuals with non-alcohol fatty liver disease (NAFLD) often have normal body size but abnormal visceral fat. Therefore, an alternative to body mass index should be considered for prediction of lean-NAFLD. This study aimed to use representative visceral fat links with other laboratory parameters using the least absolute shrinkage and selection operator (LASSO) method to construct a predictive model for lean-NAFLD.

METHODS

This retrospective cross-sectional analysis enrolled 2325 subjects with BMI < 24 kg/m2 from medical records of 51,271 examinees who underwent a routine health check-up. They were randomly divided into training and validation cohorts at a ratio of 1:1. The LASSO-derived prediction model used LASSO regression to select 23 clinical and laboratory factors. The discrimination and calibration abilities were evaluated using the Hosmer-Lemeshow test and calibration curves. The performance of the LASSO model was compared with the fatty liver index (FLI) model.

RESULTS

The LASSO-derived model included four variables-visceral fat, triglyceride levels, HDL-C-C levels, and waist hip ratio-and demonstrated superior performance in predicting lean-NAFLD with high discriminatory ability (AUC, 0.8416; 95% CI: 0.811-0.872) that was comparable with the FLI model. Using a cut-off of 0.1484, moderate sensitivity (75.69%) and specificity (79.86%), as well as high negative predictive value (95.9%), were achieved in the LASSO model. In addition, with normal WC subgroup analysis, the LASSO model exhibits a trend of higher accuracy compared to FLI (cut-off 15.45).

CONCLUSIONS

We developed a LASSO-derived predictive model with the potential for use as an alternative tool for predicting lean-NAFLD in clinical settings.

Inflammatory Bowel Disease Is an Independent Risk Factor for Metabolic Dysfunction-Associated Steatotic Liver Disease in Lean Individuals

BACKGROUND

Despite classical association between metabolic dysfunction-associated steatotic liver disease (MASLD) and obesity, there is increasing evidence on the development of MASLD in lean individuals. The aim of the study was to assess the prevalence and risk factors of MASLD and significant liver fibrosis in lean participants with inflammatory bowel disease (IBD).

METHODS

This was a cross-sectional, case-control study including 300 lean cases with IBD and 80 lean controls without IBD, matched by sex and age. All participants underwent a liver ultrasound, transient elastography, and laboratory tests.

RESULTS

The lean IBD group showed a significantly higher prevalence of MASLD compared with lean non-IBD group (21.3% vs 10%; P = .022), but no differences were observed in the prevalence of significant liver fibrosis (4.7% vs 0.0%; P = 1.000). No differences were found between the prevalence of MASLD in IBD and non-IBD participants who were overweight/obese (66.8% vs 70.8%; P = .442). In addition, the prevalence of MASLD was significantly higher in the overweight/obese IBD group compared with the lean IBD group (P < .001). IBD was an independent risk factor for MASLD in lean participants (odds ratio [OR], 2.71; 95% confidence interval [CI], 1.05-7.01; P = .04), after adjusting for classic metabolic risk factors and prior history of systemic steroid use. Nevertheless, no association between IBD related factors and MASLD was identified in lean IBD participants. When the overweight/obese and lean IBD groups with MASLD were compared, the overweight/obese IBD group with MASLD showed higher levels of the homeostatic model assessment of insulin resistance (OR, 1.49; 95% CI, 1.11-1.98; P = .007) and history of smoking (OR, 4.66; 95% CI, 1.17-18.49; P = .029).

CONCLUSIONS

MASLD prevalence was higher in the lean IBD group compared with lean non-IBD group, independent of classic metabolic risk factors.

Metabolic dysfunction-associated steatotic liver disease heterogeneity: Need of subtyping

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a widespread global disease with significant health burden. Unhealthy lifestyle, obesity, diabetes mellitus (DM), insulin resistance, and genetics have been implicated in the pathogenesis of MASLD. A significant degree of heterogeneity exists among each of above-mentioned risk factors. Heterogeneity of these risk factors translates into the heterogeneity of MASLD. On the other hand, MASLD can itself lead to insulin resistance and DM. Such heterogeneity makes it difficult to assess the natural course of an individual with MASLD in clinical practice. At present MASLD is considered as one disease despite the variability of etiopathogenic processes, and we lack the consensus definitions of unique subtypes of MASLD. In this review, pathogenic processes of MASLD are discussed and a need of subtyping is recommended.

Prevalence of Steatotic Liver Disease Based on a New Nomenclature in the Japanese Population: A Health Checkup-Based Cross-Sectional Study

This cross-sectional study examined the prevalence and characteristics of steatotic liver disease (SLD) based on a recently introduced nomenclature in the Japanese health checkup population. SLD was evaluated using liver ultrasonography, and participants were categorized into metabolic dysfunction-associated steatotic liver disease (MASLD), metabolic dysfunction and alcohol associated steatotic liver disease (MetALD), alcohol-associated/related liver disease (ALD), and cryptogenic SLD groups. The prevalence and characteristics of the SLD subclasses were assessed, and subgroup analyses were conducted for the non-obese (body mass index [BMI] ≤ 25 kg/m2) and lean (BMI ≤ 23 kg/m2) populations. Among the 694 participants, with a median age of 47 years and comprising 54% males, the prevalence of MASLD, MetALD, ALD, and cryptogenic SLD was 26%, 2%, 1%, and 2%, respectively. A remarkable difference was observed in the prevalence of SLD subclasses according to age, sex, and BMI. Subgroup analyses revealed heterogeneous demographic, clinical, and biochemical parameters between the SLD categories. Individuals with MetALD had higher gamma-glutamyl transferase levels, lower platelet counts, and higher fibrosis-4 index than did those with MASLD. Furthermore, the prevalence of non-obese and lean MASLD was 13% and 6%, respectively. This study provides preliminary information on the prevalence of SLD based on a new nomenclature in the Japanese population.

Triglycerides Mediate the Influence of Body Mass Index on Non-Alcoholic Fatty Liver Disease in a Non-Obese Chinese Population with Normal Low-Density Lipoprotein Cholesterol Levels

INTRODUCTION

Over 25% of the world's population has non-obese or lean non-alcoholic fatty liver disease (NAFLD), and the prevalence is higher than average in Asia. The present study focused on the relationship between body mass index (BMI) and non-obese NAFLD in non-overweight people in China, particularly the influence of triglycerides (TG) in the pathogenesis of non-obese NAFLD. The findings suggest new treatments for NAFLD patients with normal BMI, as well as provide an early warning system for the understanding and prevention of NAFLD in non-obese patients.

METHODS

This cross-sectional study enrolled 159,959 Chinese subjects with BMI <24 kg/m2 and normal levels of low-density lipoprotein cholesterol (LDL-c). The average age was 40.21 ± 13.88 years, and males accounted for 45.7%. A total of 15,907 (9.94%) patients with NAFLD were diagnosed by ultrasonography. Biochemical indicators were measured using an automated analyzer (Abbott AxSYM). The BMI (kg/m2) was calculated from the weight (kg)/height in square meters (m2). The BMI quartile was used as the column-stratified variable to determine the baseline distribution, and logistic regression analysis was used to assess the relationship between NAFLD and its risk factors, with multiple logistic regression used to assess the relationships between BMI or TG and NAFLD and multivariate linear regression used to analyze the association between BMI and TG, while mediation analysis was used to assess the mediation effect of TG.

RESULTS

After adjustment of all covariates, the odds ratios were 1.788 (95% CI: 1.749-1.829; p < 0.00001) and 1.491 (95% CI: 1.451-1.532; p < 0.00001) for the association between BMI and TG with NAFLD incidence. The multivariate linear regression coefficient of BMI and TG was β = 0.027 (95% CI: 0.023-0.030; p < 0.00001). Mediation analysis showed that BMI contributed to 10.81% of lean NAFLD with a mediation effect of 2.98%.

CONCLUSION

In a Chinese population with BMI <24 kg/m2 and normal LDL-c levels, BMI and TG were found to be independent predictors of NAFLD. The direct effect of BMI on non-obese NAFLD was 10.41%. The TG level was found to partially mediate the association.

Role of FGF21 and Leptin for the Diagnosis of Metabolic Health in Children with and without Obesity

Obesity and unfavorable metabolic profiles increase the risk for cardiovascular complications in adults. Although it is important to distinguish different metabolic health states at an early stage, there are limited data on the related value of biomarkers in childhood. We aimed to identify biomarkers for the detection of different metabolic health states in children with and without obesity. The serum levels of metabolic regulators (fibroblast growth factor 21 [FGF21], leptin, adiponectin and insulin-like growth factor binding protein 1) and vascular indices (flow-mediated dilation [FMD] and carotid intima-media thickness) were assessed in 78 children. Differences between the metabolically healthy and unhealthy state within children with normal weight (MHN vs. MUN), and within children with overweight/obesity (MHO vs. MUO) were investigated; the discriminatory power of the biomarkers was studied. Both MUN and MUO groups expressed altered lipid and glucose homeostasis compared to their healthy counterparts. The metabolic unhealthy state in children with normal weight was linked to higher FGF21 levels which had good discriminatory ability (area under the curve [AUC]: 0.71, 95% CI: 0.54-0.88; p = 0.044). In overweight/obese children, leptin was increased in the metabolically unhealthy subgroup (AUC: 0.81, 95% CI: 0.68-0.95; p = 0.01). There was a decrease in FMD indicating worse endothelial function in overweight/obese children versus those with normal weight. Distinct states of metabolic health exist in both children with normal weight and overweight/obese children. FGF21 and leptin may help to identify the metabolic unhealthy state in children with normal weight and in overweight/obese children, respectively, early in life.

Prevalence of non-alcoholic fatty liver and its related factors in Iran: Systematic review and meta-analysis

Non-alcoholic fatty liver disease (NAFLD) is a systemic disorder with a complex multifactorial and heterogeneous pathogenesis and has become the most common cause of chronic liver disease in many countries around the world. Numerous studies in Iran have presented different results on the prevalence and risk factors of NAFLD, in this study, which has been done in a systematic review and meta-analysis, provides a good estimate of the prevalence and risk factors of the disease in Iran. Following the peer review of electronic search strategies (PRESS and the preferred reporting items for systematic reviews and meta-analyses [PRISMA] statement, we searched Web of Science, PubMed, Embase, Scopus, and Persian scientific searcher (Elmnet) from inception to September 19, 2022. In the present study, 71 articles were reviewed for qualitative and meta-analysis. The overall mean prevalence of NAFLD in children studies was 22.4% (95% confidence interval [CI]: 10.9% to 33.9%). The prevalence was notably higher in adult studies 40.5% (95% CI: 35.1% to 46%). In 24 studies, the association between NAFLD and sex was reported, 10 of which showed significant relationships. Out of 46 studies observed that NAFLD prevalence increased significantly with body mass index (BMI). Eight out of 14 studies reported significant associations between FBS and NAFLD in children's studies. Though Iran has a high NAFLD prevalence compared to most areas, and due to the unfavorable situation of risk factors contributing to the NAFLD, it is necessary to take the necessary interventions to control these risk factors and prevent NAFLD.

Metabolic characteristics of non-obese and obese metabolic dysfunction-associated fatty liver disease in type 2 diabetes mellitus and its association with diabetic peripheral neuropathy and diabetic retinopathy

Aim

To assess the metabolic characteristics of non-obese metabolic dysfunction-associated fatty liver disease (MAFLD) compared with obese MAFLD and the relationship of MAFLD with diabetic peripheral neuropathy and diabetic retinopathy in patients with Type 2 diabetes mellitus (T2DM).

Methods

Data were obtained from 536 T2DM patients (355 women, 181 men; age 58.2 ± 12.0 years). We explored the difference in clinical characteristics between obese MAFLD (body mass index ≥25 kg/m2) and non-obese MAFLD (body mass index <25 kg/m2) in T2DM patients. One-way analysis of variance (ANOVA) was used to compare the means of continuous variables, and the Chi-squared test was used to compare the differences in frequencies of categorical variables. Logistic regression models were adopted to calculate odds ratios.

Results

The prevalence of MAFLD in hospitalized Chinese T2DM patients was calculated to be 42.7%. Both obese and non-obese MAFLD patients had higher levels of body mass index (BMI), waist circumfere nce, triglyceride, alanine aminotransferase, aspar tate aminotransferase, γ-glutamyltransferase, you nger age, higher prevalence of hyperlipidemia and shorter duration of T2DM and lower incidence of diabetic retinopathy, compared with participants with out MAFLD in the same weight group. Uric acid levels were positively correlated with the risk of MAFLD only in non-obese subjects but not in obese subjects. In non-obese patients with T2DM, a negative correlation was found between the prevalence of MAFLD and diabetic retinopathy.

Conclusion

Even in non-obese patients with T2DM, BMI was found to be an independent risk factor for MAFLD. These findings support a more structured, risk-factor-based approach to MAFLD management, particularly in patients with T2DM. Non-obese MAFLD has unique results in metabolic characteristics and the correlation with diabetic retinopathy and diabetic peripheral neuropathy, which should be further explored.

Lean nonalcoholic fatty liver disease: Age-dependent differences in pathology, prognosis, and liver-related events

AIM

This study aimed to evaluate the age-specific characteristics, prognosis, and complications of patients with lean nonalcoholic fatty liver disease (NAFLD).

METHODS

Background factors (age, sex, diabetes, dyslipidemia, hypertension, and PNPLA3 gene polymorphism), blood test results, liver histology findings, muscle mass, and grip strength were investigated in 782 patients with NAFLD who underwent liver biopsy. Prognosis and complications were compared among 549 patients with nonlean or lean NAFLD who were followed up for 6.5 years. Additionally, background factors, blood test results, liver histology findings, prognosis, and complications were compared according to age (≥60 years vs. <60 years) in patients with lean NAFLD.

RESULTS

Lean NAFLD patients showed lower aspartate aminotransferase, alanine aminotransferase, homeostasis model assessment-insulin resistance, high-sensitivity C-reactive protein, ferritin, and leptin but higher adiponectin and hemoglobin A1c (HbA1c) levels than patients with nonlean NAFLD. Furthermore, lean NAFLD patients showed less liver fibrosis, inflammation, steatosis, and ballooning. Among lean NAFLD patients, those aged 60 years and older were more frequently female, showed higher rates of hypertension, diabetes, and dyslipidemia, had higher HbA1c and type IV collagen 7S levels, lower platelet count, higher liver fibrosis and inflammation grades, and lower muscle mass and grip strength. Lean NAFLD was associated with a worse prognosis in patients aged 60 years and over than in those younger than 60 years of age and with a higher incidence of liver-related disease, cerebrocardiovascular events, and nonliver cancer.

CONCLUSIONS

Age is an important consideration in patients with lean NAFLD. Compared with nonlean NAFLD, lean NAFLD was associated with a worse prognosis and higher risk of complications in patients aged 60 years and older.

Association between the lean nonalcoholic fatty liver disease and risk of incident type 2 diabetes in a healthy population of Northwest China: a retrospective cohort study with a 2-year follow-up period

Aims

We aimed to explore the metabolic features of lean nonalcoholic fatty liver disease (Lean-NAFLD) and its association with the risk of incident type 2 diabetes in young and middle-aged people.

Methods

We conducted a retrospective cohort study of 3001 participants who were enrolled in a health check-up program from January 2018 to December 2020 in the Health Management Center of Karamay People's Hospital. The age, sex, height, weight, body mass index (BMI), blood pressure, waist circumference (WC), fasting plasma glucose (FPG), lipid profiles, serum uric acid and alanine aminotransferase (ALT) of the subjects were collected. The cutoff point of BMI for lean nonalcoholic fatty liver disease is <25 kg/m². A COX proportional hazard regression model was used to analyze the risk ratio of lean nonalcoholic fatty liver disease to type 2 diabetes mellitus.

Results

Lean NAFLD participants had many metabolic abnormalities, such as overweight and obesity with nonalcoholic fatty liver disease. Compared with lean participants without nonalcoholic fatty liver disease, the fully adjusted hazard ratio (HR) for lean participants with nonalcoholic fatty liver disease was 3.83 (95% CI 2.02-7.24, p<0.01). In the normal waist circumference group (man<90cm, woman<80 cm), compared with lean participants without NAFLD, the adjusted hazard ratios (HRs) of incident type 2 diabetes for lean participants with NAFLD and overweight or obese participants with NAFLD were 1.93 (95% CI 0.70-5.35, p>0.05) and 4.20 (95% CI 1.44-12.22, p<0.05), respectively. For excess waist circumference (man≥90 cm, woman ≥80 cm) compared with lean participants without NAFLD, the adjusted hazard ratios (HRs) of incident type 2 diabetes for lean participants with NAFLD and overweight or obese participants with NAFLD were 3.88 (95% CI 1.56-9.66, p<0.05) and 3.30 (95% CI 1.52-7.14, p<0.05), respectively.

Conclusion

Abdominal obesity is the strongest risk factor for type 2 diabetes in lean nonalcoholic fatty liver disease.

Metabolic dysfunction and nonalcoholic fatty liver disease risk in individuals with a normal body mass index

PURPOSE OF REVIEW

Nonalcoholic fatty liver disease (NAFLD) is strongly associated with obesity, but is also common in individuals with a normal body mass index (BMI), who also experience the hepatic inflammation, fibrosis, and decompensated cirrhosis associated with NAFLD progression. The clinical evaluation and treatment of NAFLD in this patient population are challenging for the gastroenterologist. A better understanding of the epidemiology, natural history, and outcomes of NAFLD in individuals with normal BMI is emerging. This review examines the relationship between metabolic dysfunction and clinical characteristics associated with NAFLD in normal-weight individuals.

RECENT FINDINGS

Despite a more favorable metabolic profile, normal-weight NAFLD patients exhibit metabolic dysfunction. Visceral adiposity may be a critical risk factor for NAFLD in normal-weight individuals, and waist circumference may be better than BMI for assessing metabolic risk in these patients. Although screening for NAFLD is not presently recommended, recent guidelines may assist clinicians in the diagnosis, staging, and management of NAFLD in individuals with a normal BMI.

SUMMARY

Individuals with a normal BMI likely develop NAFLD as a result of different etiologies. Subclinical metabolic dysfunction may be a key component of NAFLD in these patients, and efforts to better understand this relationship in this patient population are needed.

Nonalcoholic Fatty Liver Disease in Lean/Nonobese and Obese Individuals: A Comprehensive Review on Prevalence, Pathogenesis, Clinical Outcomes, and Treatment

Nonalcoholic fatty liver disease (NAFLD) is the most common liver disease worldwide, with an estimated prevalence of 25% globally. NAFLD is closely associated with metabolic syndrome, which are both becoming increasingly more common with increasing rates of insulin resistance, dyslipidemia, and hypertension. Although NAFLD is strongly associated with obesity, lean or nonobese NAFLD is a relatively new phenotype and occurs in patients without increased waist circumference and with or without visceral fat. Currently, there is limited literature comparing and illustrating the differences between lean/nonobese and obese NAFLD patients with regard to risk factors, pathophysiology, and clinical outcomes. In this review, we aim to define and further delineate different phenotypes of NAFLD and present a comprehensive review on the prevalence, incidence, risk factors, genetic predisposition, and pathophysiology. Furthermore, we discuss and compare the clinical outcomes, such as insulin resistance, dyslipidemia, hypertension, coronary artery disease, mortality, and progression to nonalcoholic steatohepatitis, among lean/nonobese and obese NAFLD patients. Finally, we summarize the most up to date current management of NAFLD, including lifestyle interventions, pharmacologic therapies, and surgical options.

Comparison of Machine Learning Models and the Fatty Liver Index in Predicting Lean Fatty Liver

The reported prevalence of non-alcoholic fatty liver disease in studies of lean individuals ranges from 7.6% to 19.3%. The aim of the study was to develop machine-learning models for the prediction of fatty liver disease in lean individuals. The present retrospective study included 12,191 lean subjects with a body mass index < 23 kg/m² who had undergone a health checkup from January 2009 to January 2019. Participants were divided into a training (70%, 8533 subjects) and a testing group (30%, 3568 subjects). A total of 27 clinical features were analyzed, except for medical history and history of alcohol or tobacco consumption. Among the 12,191 lean individuals included in the present study, 741 (6.1%) had fatty liver. The machine learning model comprising a two-class neural network using 10 features had the highest area under the receiver operating characteristic curve (AUROC) value (0.885) among all other algorithms. When applied to the testing group, we found the two-class neural network exhibited a slightly higher AUROC value for predicting fatty liver (0.868, 0.841-0.894) compared to the fatty liver index (FLI; 0.852, 0.824-0.81). In conclusion, the two-class neural network had greater predictive value for fatty liver than the FLI in lean individuals.

Epidemiological characteristics and management of nonalcoholic fatty liver disease/nonalcoholic steatohepatitis in China: A narrative review

AIM

With industrialization and spread of the westernized lifestyle, the number of people affected by non-alcoholic fatty liver disease (NAFLD)/non-alcoholic steatohepatitis (NASH) is growing rapidly in China; this has become a major public health concern. To better understand the burden and characteristics of NAFLD/NASH in China, we aim to perform a narrative review of the literature published in this field.

MATERIALS AND METHODS

We carried out a comprehensive electronic search of five English-language and three Chinese-language databases, to identify studies regarding NAFLD or NASH published from inception to November 30, 2022. Epidemiological studies of NAFLD/NASH in China were particularly noticed and summarized. We also searched the www.

CLINICALTRIALS

gov and www.chictr.org.cn websites for the registered trials on the treatment of the disease led by Chinese investigators or located in China.

RESULTS

The increasing rate of NAFLD prevalence in China is strikingly high, reaching more than twice that in western countries. The prevalence of NAFLD is nearly 30% of the general Chinese population, making it the leading cause of chronic liver diseases. The prevalence of NAFLD/NASH varies between provinces/regions, age groups, sexes, and individuals with different metabolic profiles. NAFLD co-exists in many Chinese patients with chronic hepatitis B. Since 2020, more Chinese studies have used the term metabolic-associated fatty liver disease (MAFLD), emphasizing the underlying metabolic disorders that occur concurrently with this disease. Several clinical trials involving lifestyle interventions, antidiabetic drugs, or traditional Chinese medicines, registered by Chinese investigators, have been completed or are ongoing. Moreover, several innovative targeted therapies developed in China are revolutionizing the treatment of NAFLD/NASH.

CONCLUSIONS

NAFLD has cast a heavy burden on the Chinese healthcare system. Chinese scholars are making efforts to achieve the optimal management of this disease.

Thymoquinone and quercetin protect against hepatic steatosis in association with SIRT1/AMPK stimulation and regulation of autophagy, perilipin-2, and cytosolic lipases

BACKGROUND

We sought to investigate thymoquinone (TQ)/quercetin combination in preventing hepatic steatosis (HS).

MATERIALS AND METHODS

The included rat groups; (1) Control, (2) HS model, (3) HS treated with TQ 10 mg.kg^-1.d^-1, (4) HS treated with quercetin 50 mg.kg^-1.d^-1, and (5) HS treated with both compounds for 4 weeks.

RESULTS

TQ/quercetin co-treatment augmented the anti-steatosis potential of each ingredient. The results revealed more (p < 0.001) sirtuin (SIRT1)/AMP-activated protein kinase (p-AMPK) upregulation compared to each treatment in line with autophagy protein Atg7 enhancement, and suppressed pro-inflammatory and oxidation markers. They diminished the hepatic lipogenic enzymes and perilipin-2 and activated the cytosolic lipases adipose triglyceride lipase (ATGL). Histological and Biochemical analysis revealed diminished lipid deposition and improved liver enzymes (alanine aminotransferase [ALT] and aspartate aminotransferase [AST]) compared to the data of separate treatments.

CONCLUSION

TQ and quercitin effectively upregulated SIRT1/p-AMPK and regulated hepatic perilipin-2/ATGL, inflammation and oxidative stress, preserved liver structure and function. TQ/quercetin combination additively prevents HS.

Epidemiology and prevalence of lean nonalcoholic fatty liver disease and associated cirrhosis, hepatocellular carcinoma, and cardiovascular outcomes in the United States: a population-based study and review of literature

BACKGROUNDS

Nonalcoholic fatty liver disease (NAFLD) is linked to obesity and metabolic syndrome conditions. However, a subset of NAFLD patients express a normal or low body mass index (lean NAFLD [L-NAFLD]). Our aim is to compare the prevalence of L-NAFLD to the obesity-associated NAFLD in the United States by assessing prevalence, potential risk factors, liver-related complications, and coronary artery disease outcomes.

METHODOLOGY

A multicenter database (Explorys Inc.) of >70 million patients across the United States was screened. A cohort of patients with "nonalcoholic fatty liver" between 1999 and 2021 was identified. Two sub-cohorts of NAFLD patients were identified: those with a body mass index (BMI) < 25 kg/m² (L-NAFLD) and those with a BMI > 30 kg/m² (obesity-associated NAFLD). We excluded patients with age <18 and those who have viral hepatitis, hemochromatosis, Wilson's disease, biliary cirrhosis, alcoholic liver disease, cystic fibrosis, alpha-1-antitrypsin deficiency, and autoimmune hepatitis. Multivariate analysis was performed to adjust for confounders.

RESULTS

68 892 260 individuals were screened. NAFLD prevalence was four per 100 000, and L-NAFLD prevalence was 0.6 per 100 000. Compared with those without, patients with L-NAFLD tended to be older (OR 2.16), females (OR 1.28), and smokers (OR 4.67) and of Asian race (OR 2.12). L-NAFLD patients were more likely to have acute coronary syndromes (OR 30.00) and metabolic syndrome (OR 2.31) despite the normal/low BMI. Esophageal varices and hepatocellular carcinoma risks were high in both cirrhosis patients.

CONCLUSION

This is the largest study to assess L-NAFLD prevalence in the United States. L-NAFLD are at a significantly higher risk for acute coronary syndromes, esophageal varices, and hepatocellular carcinoma.

Assessing the longitudinal association between the GGT/HDL-C ratio and NAFLD: a cohort study in a non-obese Chinese population

BACKGROUND

A cross-sectional association between the combination indicator of high-density lipoprotein cholesterol (HDL-C) and gamma-glutamyl transferase (GGT) and fatty liver has been described in several recent studies, and this study aims to further evaluate the longitudinal relationship between the ratio of GGT to HDL-C (GGT/HDL-C ratio) and nonalcoholic fatty liver disease (NAFLD).

METHODS

This cohort study included 12,126 individuals without NAFLD at baseline, followed prospectively for 5 years, and the endpoint of interest was new-onset NAFLD. The relationship of the GGT/HDL-C ratio with new-onset NAFLD and the shape of the association was assessed by Cox regression models and restricted cubic spline (RCS) regression, respectively. Time-dependent receiver operator characteristics (ROC) curves were constructed to evaluate the predictive value of GGT, HDL-C, GGT/HDL-C ratio and BMI for the occurrence of NAFLD at different time points in the future.

RESULTS

The prevalence of NAFLD was 72.46/1000 person-years during the 5-year follow-up period. Results of multivariate Cox regression analysis showed a positive association of the GGT/HDL-C ratio with new-onset NAFLD after adequate adjustment of the related confounding factors, and the degree of correlation was slightly higher than that of GGT, and further subgroup analysis found that this association was more significant in the population with elevated systolic blood pressure (SBP). In addition, we also found a nonlinear relationship of the GGT/HDL-C ratio with the risk of new-onset NAFLD using the RCS regression, where the saturation threshold was about 31.79 U/mmol. Time-dependent ROC analysis results showed that the GGT/HDL-C ratio was increasingly valuable in predicting NAFLD over time, and was better than HDL-C in predicting NAFLD in the early stage (1-3 years), but was not superior to BMI and GGT.

CONCLUSIONS

In this large longitudinal cohort study based on a Chinese population, our results supported that the GGT/HDL-C ratio was positively and nonlinearly associated with the risk of new-onset NAFLD in a non-obese population. In the assessment of future NAFLD risk, the GGT/HDL-C ratio was slightly better than GGT alone; However, the GGT/HDL-C ratio did not appear to have a significant advantage over GGT and BMI alone in predicting NAFLD.

Serum Uric Acid but Not Ferritin Level Is Associated with Hepatic Fibrosis in Lean Subjects with Metabolic Dysfunction-Associated Fatty Liver Disease: A Community-Based Study

Elevated serum ferritin and uric acid levels are common in patients with fatty liver disease. This study assessed the association between serum ferritin and uric acid levels and liver fibrosis in subjects with lean metabolic dysfunction-associated fatty liver disease (MAFLD). This cross-sectional study used data from a community screening examination for metabolic syndrome from December 2018 to September 2019 at Keelung Chang Gung Memorial Hospital. Subjects with lean MAFLD were defined as those with a body mass index (BMI) < 23 kg/m2 and hepatic steatosis according to the MAFLD criteria. A total of 182 lean subjects were included and were divided into lean MAFLD and lean healthy groups. Serum ferritin and uric acid concentrations were positively correlated with liver fibrosis, regardless of whether FIB-4, APRI, or NFS were used as references. Univariate logistic regression analysis showed that age and uric acid were associated with advanced liver fibrosis. After adjusting for potential confounders, only uric acid level was statistically significant in predicting the advanced liver fibrosis (OR = 6.907 (1.111−42.94), p = 0.038) in the lean MAFLD group. We found that an elevated serum uric acid level is an independent factor associated with advanced liver fibrosis in lean MAFLD subjects by noninvasive fibrosis scores.

Obesity, but not glycemic control, predicts liver steatosis in children with type 1 diabetes

OBJECTIVE

Nonalcoholic fatty liver disease (NAFLD), the most common liver disease in children, is strongly associated with obesity and insulin resistance. Although type 1 diabetes (T1D) is characterized by insulin deficiency, increasing obesity rates among children with T1D is a major risk factor for NAFLD in this patient population. Predisposing factors for NAFLD in children with T1D are not known.

STUDY DESIGN

This is a cross-sectional study comparing children with T1D across the range of body mass index (BMI) to the BMI-matched obese group without T1D. Hepatic steatosis was semi-quantitatively measured via the vibration-controlled transient elastogram (VCTE) method. Linear regression analysis was performed to assess the relationship between controlled-attenuated parameter (CAP) scores and clinical parameters. Receiver-operator curve (ROC) analysis was used to evaluate the diagnostic performance of several clinical parameters against NAFLD status determined via CAP.

RESULTS

Two-thirds of subjects with obesity had CAP scores suggestive of NAFLD, while 16 % (n = 6) of T1D patients without obesity had elevated CAP. Obese subjects were different from non-obese subjects in many laboratory and clinical characteristics, regardless of T1D status. CAP score was significantly associated with BMI, HDL-Cholesterol (HDL-c), and HbA1c in all subjects as well as the T1D-only subgroup. Among subjects with obesity only, age, HDL-cand ALT were the most significant predictors. Diagnostic performance of BMI, HDL-c, and BMI/HDL ratio were in the good to the excellent range for predicting NAFLD among all subjects, while performance varied for T1D-only or obesity-only groups.

CONCLUSION

The clinical and imaging findings of children with T1D and obesity are comparable to non-diabetic children with a similar degree of obesity. Obesity is the major risk factor for NAFLD in pediatric T1D. BMI, HDL-c, and BMI/HDL ratio may be helpful markers to determine further workup for NAFLD in children with T1D, particularly those with obesity.

Presence of sarcopenia identifies a special group of lean NAFLD in middle-aged and older people

BACKGROUND

Sarcopenia, the age-related loss of muscle mass and function, is closely associated and frequently concomitant with non-alcoholic fatty liver disease (NAFLD). We aimed to investigate the clinical features of the sarcopenic NAFLD patients from middle-aged and older people.

METHODS

A total of 1305 patients with NAFLD from the Shanghai Changfeng Study were included for analysis. Sarcopenia was diagnosed based on the height-adjusted appendicular skeletal muscle mass (ASM/height²). We comprehensively analyzed the metabolic phenotype, carotid artery condition, liver fibrosis score, and serum metabolomic profile of each participant.

RESULTS

Among the middle-aged and older population, 68.1% of patients with sarcopenia and NAFLD were lean. Sarcopenia was independently associated with increased risk of carotid plaque (OR, 2.22; 95%CI 1.23-4.02) and liver fibrosis (OR, 2.07; 95%CI 1.24-3.44), and the sarcopenic lean NAFLD patients were characterized by a higher risk of carotid plaque (p = 0.008) and liver fibrosis (p = 0.001) than the non-sarcopenic lean NAFLD patients, despite their lower BMI and similar prevalence of metabolic syndrome and diabetes. Further serum metabolomic examination indicated that the sarcopenic lean NAFLD patients presented a distinct metabolomic profile prone to carotid plaque and liver fibrosis, with upregulated serum valine, N-acetylneuraminyl-glycoproteins, lactic acid, small LDL triglycerides and VLDL5 components, and reduced components of HDL4. A sarcopenic characterization score based on above metabolites was established and could also predict increased risk of carotid plaque and liver fibrosis.

CONCLUSION

The presence of sarcopenia identifies a special subgroup of lean NAFLD with increased risk of cardiovascular disease and liver fibrosis clinically.

Lysosomal Acid Lipase Activity in Non-alcoholic Fatty Liver Disease as a Novel Diagnostic and Therapeutic Target: A Systematic Literature Review of Current Evidence and Future Directions

Background and aim

Non-alcoholic fatty liver disease (NAFLD) presents with the accumulation of excessive intra-hepatic fat without significant alcohol intake. Multifactorial pathogenesis is reported to be involved. Reduced lysosomal acid lipase (LAL) activity is suggested as one of the novel-involved pathogenic mechanisms. This review summarizes the available evidence on the role of LAL activity in NAFLD pathogenesis.

Methods

Four databases namely, PubMed/Medline, Science direct, Cochrane Library, and Google scholar were searched to identify relevant observational records evaluating the role of LAL activity in the pathogenesis of NAFLD. All studies were assessed for their quality by using Newcastle-Ottawa Scale or The Joanna Briggs Institute Critical Appraisal tools for cohort and cross-sectional studies, respectively. The estimates of LAL activity and other clinical outcomes were expressed as mean (SD) and number (%) as presented in the primary studies.

Results

A total of nine good quality studies with 1711 patients with NAFLD and 877 controls from different groups (healthy volunteers, alcoholics, cryptogenic cirrhosis, and HCV-positive) were included. From the NAFLD group, 59.55% were males and the overall mean age ranged between the studies from 12.6 ± 8.5 months in pediatrics to 58.90 ± 13.82 years in adults. In the NAFLD group, the LAL activity varied from 0.53 ± 0.08 to 1.3 ± 0.70 (nmol/spot/hr) between the studies which was less than all control groups except cryptogenic cirrhosis patients (0.5 ± 0.15 nmol/spot/hr). Of the other outcomes of interest, ALT, AST, total cholesterol, triglyceride, and LDL cholesterol were found elevated in NAFLD patients than in controls.

Conclusion

The current evidence suggests a potential correlation of reduced LAL activity with NAFLD pathogenesis according to its severity. Large-scale studies are recommended, more importantly in patients with NAFLD having no metabolic or genetic involvement. Further LAL can act as a new non-invasive diagnostic biomarker to identify that specific NAFLD subgroup.

Chronic intake of high dietary sucrose induces sexually dimorphic metabolic adaptations in mouse liver and adipose tissue

Almost all effective treatments for non-alcoholic fatty liver disease (NAFLD) involve reduction of adiposity, which suggests the metabolic axis between liver and adipose tissue is essential to NAFLD development. Since excessive dietary sugar intake may be an initiating factor for NAFLD, we have characterized the metabolic effects of liquid sucrose intake at concentrations relevant to typical human consumption in mice. We report that sucrose intake induces sexually dimorphic effects in liver, adipose tissue, and the microbiome; differences concordant with steatosis severity. We show that when steatosis is decoupled from impairments in insulin responsiveness, sex is a moderating factor that influences sucrose-driven lipid storage and the contribution of de novo fatty acid synthesis to the overall hepatic triglyceride pool. Our findings provide physiologic insight into how sex influences the regulation of adipose-liver crosstalk and highlight the importance of extrahepatic metabolism in the pathogenesis of diet-induced steatosis and NAFLD.

Sex-specific Cutoff Values of Visceral Fat Area for Lean vs. Overweight/Obese Nonalcoholic Fatty Liver Disease in Asians

BACKGROUND AND AIMS

Visceral obesity is a risk factor for nonalcoholic fatty liver disease (NAFLD). We investigated sex-specific optimal cutoff values for visceral fat area (VFA) associated with lean and overweight/obese NAFLD in an Asian population.

METHODS

This retrospective study included 678 potential living liver donors (mean age, 30.8±9.4 years; 434 men and 244 women) who had undergone abdominal computed tomography (CT) imaging and liver biopsy between November 2016 and October 2017. VFA was measured using single-slice abdominal CT. NAFLD was evaluated by liver biopsy (≥5% hepatic steatosis). Receiver operating characteristic curve analysis was used to determine cutoff values for VFA associated with lean (body mass index [BMI] <23 kg/m²) and overweight/obese (BMI ≥23 kg/m²) NAFLD.

RESULTS

Area under the curve (AUC) values with 95% confidence intervals (CI) for VFA were 0.82 (95% CI, 0.75-0.88) for lean and 0.74 (95% CI, 0.69-0.79) for overweight/obese men with NAFLD. The AUC values were 0.67 (95% CI, 0.58-0.75) for lean and 0.71 (95% CI, 0.62-0.80) for overweight/obese women with NAFLD. The cutoff values for VFA associated with lean NAFLD were 50.2 cm² in men and 40.5 cm² in women. The optimal cutoff values for VFA associated with overweight/obese NAFLD were 100.6 cm² in men and 68.0 cm² in women.

CONCLUSIONS

Sex-specific cutoff values for VFA may be useful for identifying subjects at risk of lean and overweight/obese NAFLD.

Metabolically associated fatty liver disease – a disease of the 21st century: A review

Metabolically associated fatty liver disease (MAFLD) is a widespread chronic disease characterized by increased accumulation of fat in the liver, which is based on metabolic dysfunction. The incidence of MAFLD is well over 20% in most regions of the world and is on an increasing trend. Current thinking considers the etiology and pathogenesis of MAFLD under the concept of "multiple parallel blows". According to this model, the development and progression of the disease are due to the interaction of multiple genetic, environmental and adaptive factors, which include specific genetic polymorphisms (e.g., the PNPLA3 gene) and epigenetic modifications, dietary patterns (e.g. high saturated fat and fructose intake), sedentary activity, obesity, insulin resistance, dysregulation of adipokines, lipotoxicity, oxidative stress, and gut microbiota dysbiosis (small intestinal bacterial overgrowth syndrome). The basis for the diagnosis of MAFLD is the presence of proven hepatic steatosis in combination with one of the following criteria: overweight/obesity, presence of type 2 diabetes mellitus, signs of metabolic dysregulation. Nonmedicamental therapies recommended for patients with MAFLD include weight loss (if overweight or obese), reduction of saturated fatty acid and fructose intake, and inclusion of adequate amounts of omega-3 polyunsaturated fatty acids and dietary fibre (psyllium) in the diet. Pharmacotherapy of MAFLD should be aimed at correcting insulin resistance, improving liver function and reducing the risk of associated diseases.

Mid-upper arm circumference is associated with liver steatosis and fibrosis in patients with metabolic-associated fatty liver disease: A population based observational study

Metabolic-associated fatty liver disease (MAFLD) is a series of liver diseases based on liver steatosis and metabolic disorders. Steatosis, as the core factor in MAFLD diagnosis, and fibrosis, as the major determinant of adverse outcomes of MAFLD, need to be assessed simply and accurately. In this study, we explored the significance of mid-upper arm circumference (MUAC) in evaluating liver steatosis and fibrosis in patients with MAFLD. We included 2397 cases with MAFLD from the 2017-2018 National Health and Nutrition Examination Surveys (NHANES) database. Liver steatosis and fibrosis were measured by vibration controlled transient elastography. Anthropometric parameters and demographic and serological data were obtained from the NHANES database. The association between MUAC and liver steatosis and fibrosis were evaluated by a multivariable linear regression model, a weighted generalized additive model, and smooth curve fitting using R. MUAC was positively associated with liver steatosis in every multivariate linear regression model (model 1: β = 3.3513; 95% confidence interval [CI], 2.7722-3.9304; model 2: β = 3.8492; 95% CI, 3.2441-4.4542; model 3: β = 2.4987; 95% CI, 1.8371-3.1604), and this positive association was consistent in both men and women and among different race groups (Mexican American, other Hispanic, non-Hispanic White, Black, Asian, and other race). On the other hand, MUAC was positively associated with liver fibrosis in every multivariate linear regression model, and this positive association also was consistent in both men and women and among non-Hispanic White and Black populations. Increased MUAC was positively associated with liver steatosis and fibrosis in patients with MAFLD. This was particularly true for MUAC ≥ 42.0 cm. MUAC might be a simple and convenient evaluation tool for MAFLD.

Comparative Transcriptome Analysis Reveals That Exendin-4 Improves Steatosis in HepG2 Cells by Modulating Signaling Pathways Related to Lipid Metabolism

No therapy exists for non-alcoholic fatty liver disease (NAFLD). However, glucagon-like peptide receptor agonists (GLP-1RAs) showed a beneficial effect on NAFLD, although the underpinning mechanisms remain unclear due to their pleiotropic effects. We examined the implicated signaling pathways using comparative transcriptomics in a cell model of steatosis to overcome pleiotropy. We treated steatotic HepG2 cells with the GLP-1RA Exendin-4 (Ex-4). We compared the transcriptome profiles of untreated steatotic, and Ex-4-treated steatotic cells, and used Ingenuity Pathway Analysis (IPA) to identify the signaling pathways and associated genes involved in the protective effect of Ex-4. Ex-4 treatment significantly reduces steatosis. RNA-seq analysis revealed 209 differentially expressed genes (DEGs) between steatotic and untreated cells, with farnesoid X receptor/retinoid X receptor (FXR/RXR) (p = 8.9 × 10−7) activation being the top regulated canonical pathway identified by IPA. Furthermore, 1644 DEGs were identified between steatotic cells and Ex-4-treated cells, with liver X receptor/retinoid X receptor (LXR/RXR) (p = 2.02 × 10−7) and FXR/RXR (p = 3.28 × 10−7) activation being the two top canonical pathways. The top molecular and cellular functions between untreated and steatotic cells were lipid metabolism, molecular transport, and small molecular biochemistry, while organismal injury and abnormalities, endocrine system disorders, and gastrointestinal disease were the top three molecular and cellular functions between Ex-4-treated and steatotic cells. Genes overlapping steatotic cells and Ex-4-treated cells were associated with several lipid metabolism processes. Unique transcriptomic differences exist between steatotic cells and Ex-4-treated steatotic cells, providing an important resource for understanding the mechanisms that underpin the protective effect of GLP-1RAs on NAFLD and for the identification of novel therapeutic targets for NAFLD.

Non-Alcoholic Fatty Liver Disease and the Risk of Diabetes Mellitus by Menopausal Status: A Nationwide Cohort Study

Background: Non-alcoholic fatty liver disease (NAFLD) is regarded as a risk factor for type 2 diabetes mellitus (DM). Menopausal status also influences T2DM risk, where estrogen is presumed to play a protective role by decreasing insulin resistance. As such, we investigated the association between NAFLD and DM risk according to menopausal status. Objectives: We sought to examine the association between NAFLD and DM incidence in pre- and post-menopausal women. Methods: A total of 842,772 pre-menopausal and 1,074,767 post-menopausal women who underwent health examinations between 2009 and 2014 were included from the Korean National Health Insurance Service database. Multivariate Cox proportional hazard analyses were performed to evaluate the association between the risk of DM according to menopausal status and NAFLD, defined by a fatty liver index >60. Results: During the mean follow-up period (7.8 years), DM was diagnosed in 33,461 (4.0%) of pre-menopausal women and 121,102 (9.4%) post-menopausal women. A stronger association between NAFLD and the risk of DM was found in pre-menopausal women (multivariable-adjusted hazard ratio [aHR], 3.60; 95% confidence interval [CI], 3.48−3.71) than in post-menopausal women (aHR, 2.24; 95% CI, 2.21−2.28) (P-interaction < 0.01). Subgroup analyses among women aged 45 to 55 years also showed a stronger association in pre-menopausal (aHR, 3.35; 95% CI, 3.21−3.49) than in post-menopausal women (aHR, 2.83; 95% CI, 2.68−2.98) (P-interaction < 0.01). Conclusions: The association between NAFLD and DM was stronger in pre-menopausal women than in post-menopausal women. This might be due to the protective effect of estrogen, which is possibly in higher production in the peripheral fat tissue of post-menopausal women with NAFLD.

NAFLD in normal weight individuals

Nonalcoholic fatty liver disease (NAFLD) can develop in lean individuals. Despite a better metabolic profile, the risk of disease progression to hepatic inflammation, fibrosis, and decompensated cirrhosis in the lean is similar to that in obesity-related NAFLD and lean individuals may experience more severe hepatic consequences and higher mortality relative to those with a higher body mass index (BMI). In the absence of early symptoms and abnormal laboratory findings, lean individuals are not likely to be screened for NAFLD or related comorbidities; however, given the progressive nature of the disease and the increased risk of morbidity and mortality, a clearer understanding of the natural history of NAFLD in lean individuals, as well as efforts to raise awareness of the potential health risks of NAFLD in lean individuals, are warranted. In this review, we summarize available data on NAFLD prevalence, clinical characteristics, outcomes, and mortality in lean individuals and discuss factors that may contribute to the development of NAFLD in this population, including links between dietary and genetic factors, menopausal status, and ethnicity. We also highlight the need for greater representation of lean individuals in NAFLD-related clinical trials, as well as more studies to better characterize lean NAFLD, develop improved screening algorithms, and determine specific treatment strategies based on underlying etiology.

Therapeutic developments in metabolic dysfunction-associated fatty liver disease

Metabolic dysfunction-associated fatty liver disease (MAFLD) has become one of the most prevalent chronic liver diseases worldwide, bringing risk of multiorgan disfunctions including cardiovascular events, complications of cirrhosis, and even malignance. In terms of health burden management, screening patients with high risk of MAFLD and providing individual comprehensive treatment is critical. Although there are numerous agents entering clinical trials for MAFLD treatment every year, there is still no effective approved drug. The nomenclature of MAFLD highlighted the concomitant metabolic disorders and obesity. MAFLD patients with type 2 diabetes had higher risk of developing liver cirrhosis and cancer, and would benefit from anti-hyperglycemic agents; overweight and obese patients may benefit more from weight loss therapies; for patients with metabolic syndrome, individual comprehensive management is needed to reduce the risk of adverse outcomes. In this review, we introduced the current status and advances of the treatment of MAFLD based on weight loss, improving insulin resistance, and management of cardiometabolic disorders, in order to provide individualized therapy approaches for patients with MAFLD.

Prevalence and risk factors of metabolic-associated fatty liver disease during 2014-2018 from three cities of Liaoning Province: an epidemiological survey

OBJECTIVE

To investigate the incidence and characteristics of metabolic-associated fatty liver disease (MAFLD) in individuals undergoing physical examination in Liaoning Province (China).

DESIGN

Retrospective study.

SETTING

Single centre.

PARTICIPANTS

Adults who underwent routine health examination at Xikang Medical Center in Liaoning Province (Shenyang, Dandong and Dalian cities) between January 2014 and December 2018.

RESULTS

Among the 204 394 included subjects, 71 756 were diagnosed with MAFLD, accounting for 35.28%. The total prevalence of MAFLD in Shenyang, Dandong and Dalian cities over the past 5 years was 35.8%, 40.41% and 31.7%, respectively. Men had a prevalence of 46.12%, which was higher than in women (21.80%). The percentage of MAFLD in body mass index (BMI) <23 kg/m² and ≥23 kg/m² was 6.49% and 53.23%, respectively. In all subjects, BMI, systolic blood pressure, diastolic blood pressure (DBP), fasting blood glucose (FBG), triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), alanine transaminase, aspartate transaminase (AST), alkaline phosphatase (ALP), γ-glutamyl transferase (GGT), blood urea nitrogen, serum creatinine (SCr), serum uric acid (SUA), haematocrit (HCT), mean corpuscular volume (MCV) and urine protein were independently associated with MAFLD (all p<0.001). In lean subjects, DBP, FBG, TG, TC, LDL-C, HDL-C, AST, ALP, GGT, SCr, SUA, HCT and MCV were independently associated with MAFLD (all p<0.001).

CONCLUSION

The prevalence of MAFLD in Liaoning Province was found to be associated with sex, cities with different economic statuses, BMI and multiple metabolic indicators.

Non-alcoholic fatty liver disease in type 1 diabetes: Prevalence and pathophysiology

Non-alcoholic fatty liver disease (NAFLD) is the most frequent chronic liver disease in the general population with a global prevalence of 25%. It is often associated with metabolic syndrome and type 2 diabetes, as insulin resistance and hyperinsulinemia are known to be favoring factors. Recent studies have described growing incidence of NAFLD in type 1 diabetes (T1D) as well. Although increasing prevalence of metabolic syndrome in these patients seems to explain part of this increase in NAFLD, other underlying mechanisms may participate in the emergence of NAFLD. Notably, some genetic factors are more associated with fatty liver disease, but their prevalence in T1D has not been evaluated. Moreover, oxidative stress, poor glucose control and long-lasting hyperglycemia, as well as exogenous insulin administration play an important role in intrahepatic fat homeostasis. The main differential diagnosis of NAFLD in T1D is glycogenic hepatopathy, which needs to be considered mostly in T1D patients with poor glycemic control. This article aims to review the prevalence and pathophysiology of NAFLD in T1D and open perspectives for clinicians taking care of T1D patients with potential hepatopathy.

Heterogeneity of non-alcoholic fatty liver disease: Implications for clinical practice and research activity

Non-alcoholic fatty liver disease (NAFLD) is a heterogeneous condition with a wide spectrum of clinical presentations and natural history and disease severity. There is also substantial inter-individual variation and variable response to a different therapy. This heterogeneity of NAFLD is in turn influenced by various factors primarily demographic/dietary factors, metabolic status, gut microbiome, genetic predisposition together with epigenetic factors. The differential impact of these factors over a variable period of time influences the clinical phenotype and natural history. Failure to address heterogeneity partly explains the sub-optimal response to current and emerging therapies for fatty liver disease. Consequently, leading experts across the globe have recently suggested a change in nomenclature of NAFLD to metabolic-associated fatty liver disease (MAFLD) which can better reflect current knowledge of heterogeneity and does not exclude concomitant factors for fatty liver disease (e.g. alcohol, viral hepatitis, etc.). Precise identification of disease phenotypes is likely to facilitate clinical trial recruitment and expedite translational research for the development of novel and effective therapies for NAFLD/MAFLD.

Risk factors of nonalcoholic fatty liver disease in lean body mass population: A systematic review and meta-analysis

The pathophysiology and risk factors of nonalcoholic fatty liver disease (NAFLD) among lean patients is poorly understood and therefore investigated. We performed a meta-analysis of observational studies. Of 1175 articles found through searching from Medline/PubMed, Banglajol, and Google Scholar by two independent investigators, 22 were selected. Data from lean (n = 6768) and obese (n = 9253) patients with NAFLD were analyzed; lean (n = 43 398) and obese (n = 9619) subjects without NAFLD served as controls. Age, body mass index, waist circumference, systolic blood pressure, and diastolic blood pressure (DBP) had significantly higher estimates in lean NAFLD patients than in lean non-NAFLD controls. Fasting blood sugar [MD(mean difference) 5.17 mg/dl, 95% CI(confidence interval) 4.14-6.16], HbA1c [MD 0.29%, 95% CI 0.11-0.48], and insulin resistance [HOMA-IR] [MD 0.49 U, 95% CI 0.29-0.68]) were higher in lean NAFLD patients than in lean non-NAFLD controls. All components of the lipid profile were raised significantly in the former group except high-density lipoprotein. An increased uric acid (UA) level was found to be associated with the presence of NAFLD among lean. Cardio-metabolic profiles of nonlean NAFLD patients significantly differs from the counter group. However, the magnitude of the difference of lipid and glycemic profile barely reached statistical significance when subjects were grouped according to lean and nonlean NAFLD. But DBP (slope: 0.19, P < 0.037), HOMA-IR (slope: 0.58, P < 0.001), and UA (slope: 0.36, P = 0.022) were significantly higher if NAFLD was present compared to that of non-NAFLD group. Lean and nonlean NAFLD patients are metabolically similar and share common risk factors.

Non-Alcoholic Fatty Liver Disease in Lean and Non-Obese Individuals: Current and Future Challenges

Non-alcoholic fatty liver disease (NAFLD), which approximately affects a quarter of the world’s population, has become a major public health concern. Although usually associated with excess body weight, it may also affect normal-weight individuals, a condition termed as lean/non-obese NAFLD. The prevalence of lean/non-obese NAFLD is around 20% within the NAFLD population, and 5% within the general population. Recent data suggest that individuals with lean NAFLD, despite the absence of obesity, exhibit similar cardiovascular- and cancer-related mortality compared to obese NAFLD individuals and increased all-cause mortality risk. Lean and obese NAFLD individuals share several metabolic abnormalities, but present dissimilarities in genetic predisposition, body composition, gut microbiota, and susceptibility to environmental factors. Current treatment of lean NAFLD is aimed at improving overall fitness and decreasing visceral adiposity, with weight loss strategies being the cornerstone of treatment. Moreover, several drugs including PPAR agonists, SGLT2 inhibitors, or GLP-1 receptor agonists could also be useful in the management of lean NAFLD. Although there has been an increase in research regarding lean NAFLD, there are still more questions than answers. There are several potential drugs for NAFLD therapy, but clinical trials are needed to evaluate their efficacy in lean individuals.

The Risk of Type 2 Diabetes and Coronary Artery Disease in Non-obese Patients With Non-alcoholic Fatty Liver Disease: A Cohort Study

Background: Non-alcoholic fatty liver disease (NAFLD) is not uncommon in non-obese subjects, referred to as non-obese NAFLD. It is not fully determined whether non-obese NAFLD is associated with increased risks of type 2 diabetes (T2D) and coronary artery disease (CAD) in Chinese. This study aimed to examine the association between NAFLD and risks of T2D and CAD in a non-obese Chinese population. Methods: The present cohort study included two stages. In the first cross-sectional study, 16,093 non-obese subjects with a body max index (BMI) < 25.0 kg/m² were enrolled from The Second Xiangya Hospital, China, from 2011 to 2014. Hepatic steatosis was evaluated by ultrasonography examination. Logistic regression analyses were used to examine the association of non-obese NAFLD with T2D and CAD at baseline. In the subsequent 5-year follow-up study, 12,649 subjects free of T2D and CAD at baseline were included, and the incidence of T2D and CAD were observed. Cox proportional hazard regression analyses were performed to determine the risk of incident T2D and CAD with NAFLD. Results: At baseline, the prevalence of NAFLD, T2D and CAD were 10.7% (1,717/16,093), 3.3% (529/16,093) and 0.7% (113/16,093), respectively. The univariate logistic regression analyses showed NAFLD associated with both T2D and CAD. Moreover, in a multivariate logistic regression model, NAFLD remained independently associated with T2D (OR: 2.7, 95% CI: 2.2-3.3, p < 0.001). However, no significant association was found between NAFLD and CAD by the multivariate logistic regression analyses (OR: 1.1, 95% CI: 0.6-1.8, p = 0.854). During a 5-year follow-up period, 177 (1.4%) patients developed T2D, and 134 (1.1%) developed CAD, respectively. In univariate Cox regression models, NAFLD associated with both T2D and CAD. Moreover, the multivariate Cox regression analysis revealed that NAFLD independently associated with an increased risk of T2D (HR: 2.3, 95% CI: 1.7-3.2, p < 0.001). However, the association between NAFLD and incident CAD was lost in the multivariate Cox regression analysis (HR = 1.5, 95% CI: 1.0-2.4, p = 0.059). Conclusions: NAFLD was an independent risk factor for T2D in non-obese subjects. However, no significant association was observed between non-obese NAFLD and incident CAD after adjusting other traditional cardiovascular risk factors, suggesting these factors might mediate the increased incidence of CAD in non-obese NAFLD patients.

Risk of Cardiovascular Disease in Individuals With Nonobese Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is independently associated with obesity and cardiovascular disease (CVD). CVD is the primary cause of mortality in the predominantly obese population of adults with NAFLD. NAFLD is increasingly seen in individuals who are lean and overweight (i.e., nonobese), but it is unclear whether their risk of CVD is comparable to those with NAFLD and obesity. Using a prospective cohort of patients with NAFLD, we compared the prevalence and incidence of CVD in individuals with and without obesity. NAFLD was diagnosed by biopsy or imaging after excluding other chronic liver disease etiologies. Logistic regression was used to compare the odds of baseline CVD by obesity status. Cox proportional hazards regression was used to evaluate obesity as a predictor of incident CVD and to identify predictors of CVD in subjects with and without obesity. At baseline, adults with obesity had a higher prevalence of CVD compared to those without obesity (12.0% vs. 5.0%, P = 0.02). During follow-up, however, obesity did not predict incident CVD (hazard ratio [HR], 1.24; 95% confidence interval [CI], 0.69-2.22) or other metabolic diseases. Findings were consistent when considering body mass index as a continuous variable and after excluding subjects who were overweight. Age (adjusted HR [aHR], 1.05; 95% CI, 1.03-1.08), smoking (aHR, 4.61; 95% CI, 1.89-11.22), and decreased low-density lipoprotein levels (aHR, 0.98; 95% CI, 0.96-1.00) independently predicted incident CVD in the entire cohort, in subjects with obesity, and in those without obesity, respectively. Conclusion: Individuals with overweight or lean NAFLD are not protected from incident CVD compared to those with NAFLD and obesity, although CVD predictors appear to vary between these groups. Patients without obesity also should undergo rigorous risk stratification and treatment.

Nonalcoholic fatty liver disease (NAFLD) from pathogenesis to treatment concepts in humans

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) comprises hepatic alterations with increased lipid accumulation (steatosis) without or with inflammation (nonalcoholic steatohepatitis, NASH) and/or fibrosis in the absence of other causes of liver disease. NAFLD is developing as a burgeoning health challenge, mainly due to the worldwide obesity and diabetes epidemics.

SCOPE OF REVIEW

This review summarizes the knowledge on the pathogenesis underlying NAFLD by focusing on studies in humans and on hypercaloric nutrition, including effects of saturated fat and fructose, as well as adipose tissue dysfunction, leading to hepatic lipotoxicity, abnormal mitochondrial function, and oxidative stress, and highlights intestinal dysbiosis. These mechanisms are discussed in the context of current treatments targeting metabolic pathways and the results of related clinical trials.

MAJOR CONCLUSIONS

Recent studies have provided evidence that certain conditions, for example, the severe insulin-resistant diabetes (SIRD) subgroup (cluster) and the presence of an increasing number of gene variants, seem to predispose for excessive risk of NAFLD and its accelerated progression. Recent clinical trials have been frequently unsuccessful in halting or preventing NAFLD progression, perhaps partly due to including unselected cohorts in later stages of NAFLD. On the basis of this literature review, this study proposed screening in individuals with the highest genetic or acquired risk of disease progression, for example, the SIRD subgroup, and developing treatment concepts targeting the earliest pathophysiolgical alterations, namely, adipocyte dysfunction and insulin resistance.

Comparison of clinical and metabolic profiles of lean versus non-lean nonalcoholic fatty liver disease

BACKGROUND

Data on nonalcoholic fatty liver disease (NAFLD) in the Philippines are scarce. We aimed to compare the clinical and biochemical profiles of lean (BMI<23) vs. non-lean (BMI≥23) NAFLD patients.

METHODS

Consecutive patients diagnosed with NAFLD on ultrasound in two outpatient hepatology clinics from February 2007-January 2017 were included. Patients with significant alcohol intake, alternative causes of steatosis, and incomplete data were excluded.

RESULTS

A total of 663 patients (57.9% male) were included. Most patients were non-lean (88.1%) and had an elevated alanine aminotransferase (ALT) (63%). Cirrhosis or hepatocellular carcinoma (HCC) were already present in 8.4% on initial consultation. Concomitant hepatitis B was equally common in patients with and without cirrhosis (20.7% vs. 17.5%; p=0.660) or HCC (17.9% vs. 12.8%; p=0.415). Independent factors associated with HCC/cirrhosis on initial consultation were older age (OR=1.038), low albumin (OR=0.428), high BARD score (BMI, AST/ALT ratio, T2 diabetes mellitus; OR=2.548) and the presence of symptoms (OR=1.808). Compared to lean NAFLD patients, non-lean patients were more likely to be younger (51.5±14.4 vs. 55±14.3; p=0.003), have DM (47.9% vs. 29.1%; p=0.002), hypertension (57.5% vs. 38%; p=0.001), dyslipidemia (73.1% vs. 54.4%; p=0.001) and metabolic syndrome (60.3% vs. 30.4%; p<0.0001), abnormal metabolic parameters (LDL-C, HDL-C, triglycerides, uric acid and FBS), and with elevated ALT (65.2% vs. 46.8%; p=0.002) and AST (41.1±29.6 vs. 35.3±28.3; p=0.008).

CONCLUSIONS

The proportion of lean NAFLD was 11.9%. Although metabolic derangements and its clinical consequences were present in about a third of lean patients, these were still more common in non-lean NAFLD. Cirrhosis or HCC were already present in a significant proportion (8.4%) of NAFLD patients on initial presentation.

PPARGC1A rs8192678 G>A polymorphism affects the severity of hepatic histological features and nonalcoholic steatohepatitis in patients with nonalcoholic fatty liver disease

BACKGROUND

The association between PPARGC1A rs8192678 and nonalcoholic fatty liver disease (NAFLD) requires further confirmation. In addition, it is still unknown whether PPARGC1A rs8192678 is associated with hepatic histological features in NAFLD in the Chinese population.

AIM

To investigate the interaction between PPARGC1A rs8192678 and nonalcoholic steatohepatitis (NASH), and whether this polymorphism is associated with hepatic histological features.

METHODS

Fifty-nine patients with liver biopsy-proven NAFLD and 93 healthy controls were recruited to a cohort representing the Chinese Han population. The SAF (steatosis, activity, and fibrosis) scoring system was used for hepatic histopathological evaluation. The polymorphisms of PPARGC1A rs8192678 and patatin-like phospholipase domain-containing protein 3 (PNPLA3) rs738409 were genotyped. The intrahepatic mRNA expression of PPARGC1A was evaluated by real-time polymerase chain reaction.

RESULTS

Thirty-seven patients with NAFLD had NASH, of which 12 were nonobese. The PPARGC1A rs8192678 risk A allele (carrying GA and AA genotypes) had the lowest P value in the dominant model; the odds ratio (OR) for NAFLD was 2.321 [95% confidence interval (CI): 1.121-4.806]. After adjusting for age, sex, and the PNPLA3 rs738409 risk G allele, the PPARGC1A rs8192678 A allele was a risk factor for NAFLD (OR 2.202, 95%CI: 1.030-4.705, P = 0.042). The genetic analysis showed that patients with NAFLD, moderate-to-severe steatosis (S2-3), and Activity 2-4 (A ≥ 2) were more likely to carry A in PPARGC1A rs8192678 (OR 5.000, 95%CI: 1.343-18.620, P = 0.012; and OR 4.071, 95%CI: 1.076-15.402, P = 0.031). The multivariate logistic regression analysis showed that PPARGC1A rs8192678 risk A allele was also independently associated with S2-3, A ≥ 2, and NASH (OR 6.190, 95%CI: 1.508-25.410, P = 0.011; OR 4.506, 95%CI 1.070-18.978, P = 0.040; and OR 6.337, 95%CI: 1.135-35.392, P = 0.035, respectively) after adjusting for age, sex, body mass index, and PNPLA3 rs738409 risk G allele. The results also showed that this polymorphism was associated with nonobese NASH (OR 22.000, 95%CI: 1.540-314.292, P = 0.021). The intrahepatic expression of PPARGC1A mRNA was significantly lower in the group of patients who carried the risk A allele (P = 0.014).

CONCLUSION

The PPARGC1A rs8192678 risk A allele is associated with NAFLD, and with S2-3, A ≥ 2 and NASH in NAFLD patients, independent of PNPLA3 rs738409, and may be associated with nonobese NASH.

A review of non-alcoholic fatty liver disease in non-obese and lean individuals

Non-alcoholic fatty liver disease (NAFLD) is one of the most common causes of hepatic disorders. It represents a wide range of chronic liver diseases in patients with no history of significant alcohol consumption, starting with simple steatosis and progressing towards non-alcoholic steatohepatitis, cirrhosis, and ultimately hepatocellular carcinoma. NAFLD is usually associated with type 2 diabetes mellitus, dyslipidemia, metabolic syndrome, and obesity. This disease has mostly been studied in obese individuals; however, it has been widely reported and studied among the lean/non-obese population in recent years. The pathogenesis of NAFLD in non-obese patients is associated with various genetic predispositions, particularly a patatin-like phospholipase domain-containing protein 3 G allele polymorphism, which results in the accumulation of triglyceride in the liver and resistance to insulin. Additionally, dietary factors such as high fructose consumption seem to play a substantial role in the pathology of non-obese NAFLD. Although there is not enough evidence on the treatment of NAFLD in non-obese patients, the standard approach is to advise altering one's lifestyle in order to diminish visceral adiposity. Dietary modification, weight loss, and increased physical activity are highly recommended. We aimed to review and summarize the existing information on the prevalence, pathogenesis, genetic predispositions, diagnosis, and treatment of NAFLD in non-obese patients according to the latest literature.

Hepatic stellate cells-specific LOXL1 deficiency abrogates hepatic inflammation, fibrosis, and corrects lipid metabolic abnormalities in non-obese NASH mice

BACKGROUND AND AIMS

Lysyl oxidase-like-1 (LOXL1), a vital cross-linking enzyme in extracellular matrix (ECM) maintenance, promotes fibrosis via enhancement of ECM stability. However, the potential role of LOXL1 in the pathogenesis of nonalcoholic steatohepatitis (NASH) has not been previously studied.

METHODS

We generated Loxl1^fl/fl mice to selectively delete LOXL1 in hepatic stellate cells (HSCs) (Loxl1^fl/flGfap^cre; Loxl1^fl/fl as littermate controls) and then examined liver pathology and metabolic profiles in Loxl1^fl/flGfap^cre fed with either a choline-deficient L-amino acid-defined (CDAA) diet or an isocaloric control diet for 16 weeks. Thereafter, the findings from the animal model were confirmed in 23 patients with biopsy-proven non-alcoholic fatty liver disease (NAFLD).

RESULTS

LOXL1 was significantly increased in CDAA induced non-obese NASH compared with the control diet, and LOXL1 deficient in HSCs ameliorated CDAA-induced inflammation and fibrosis, with reduced expression of pro-inflammation and pro-fibrogenic genes in the HSCs-specific LOXL1 knockout mice model. Interestingly, LOXL1 deficient in HSCs could attenuate hepatic steatosis and reverse the metabolic disorder by restoring adipose tissue function without altering the effect of hepatic lipogenesis gene expression in non-obese NASH model. More importantly, analyses of serum LOXL1 and leptin levels from NAFLD patients revealed that LOXL1 was positively correlated with histological fibrosis progression, whereas it was inversely correlated with leptin levels, especially in non-obese NAFLD patients.

CONCLUSION

LOXL1 may contribute to fibrosis progression in non-obese NAFLD, and HSCs-specific knockout of LOXL1 attenuated liver steatosis, inflammation, fibrosis, , and improved lipid metabolic abnormalities. Hence, LOXL1 inhibition may serve as a new therapeutic strategy for NASH.

Nonalcoholic Fatty Liver Disease in Lean Subjects: Associations With Metabolic Dysregulation and Cardiovascular Risk-A Single-Center Cross-Sectional Study

INTRODUCTION

Although a milder metabolic phenotype of nonalcoholic fatty liver disease (NAFLD) in lean patients (body mass index [BMI] <25 kg/m2) compared to overweight/obese patients with NAFLD is assumed, the relevance of NAFLD among lean subjects remains a matter of debate. We aimed to characterize the metabolic/cardiovascular phenotype of lean patients with NAFLD.

METHODS

In total, 3,043 subjects (cohort I) and 1,048 subjects (cohort II) undergoing screening colonoscopy between 2010 and 2020 without chronic liver disease other than NAFLD were assigned to one of the following groups: lean patients without NAFLD, lean NAFLD, overweight NAFLD (BMI 25-30 kg/m2), and obese NAFLD (BMI >30 kg/m2). Diagnosis of NAFLD was established using ultrasound (cohort I) and controlled attenuation parameter (cohort II).

RESULTS

The prevalence of lean patients with NAFLD was 6.7%/16.1% in the overall cohort I/II and 19.7%/40.0% in lean subjects of cohort I/II. Compared with lean subjects without NAFLD, lean patients with NAFLD had a higher prevalence of dyslipidemia, dysglycemia, and the metabolic syndrome, together with a higher median Framingham risk score in both cohorts (all P < 0.001). On multivariable analyses, NAFLD in lean subjects was associated with higher odds of metabolic syndrome (adjusted odds ratio cohort I: 4.27 [95% confidence interval (CI): 2.80-6.51], P < 0.001; cohort II: 2.97 [95% CI: 1.40-6.33], P < 0.001), and higher Framingham risk score (regression coefficient B cohort I: 1.93 [95% CI: 0.95-2.92], P < 0.003; cohort II: 1.09 [95% CI: 0.81-2.10], P = 0.034), among others. Only 69.8% of lean patients with NALFD in cohort I and 52.1% in cohort II fulfilled the novel criteria for metabolic associated fatty liver disease.

DISCUSSION

NAFLD in lean patients is associated with the metabolic syndrome and increased cardiovascular risk. Novel metabolic associated fatty liver disease criteria leave a considerable proportion of patients unclassified.

Visceral fat area to appendicular muscle mass ratio as a predictor for nonalcoholic fatty liver disease independent of obesity

OBJECTIVE

Obesity and sarcopenia are known to be closely related to nonalcoholic fatty liver disease (NAFLD). We attempted to explore the combined influence of fat and muscle tissue on NAFLD by using visceral fat area to appendicular muscle mass ratio (VAR) as a novel parameter.

MATERIAL AND METHODS

In this cross-sectional study, a total of 3255 adults (1399 men and 1856 women) coming for a health examination were enrolled. NAFLD was diagnosed using ultrasound and VAR was measured by bioelectrical impedance analyzer.

RESULTS

The prevalence of NAFLD was 46.5% in men and 26.6% in women. VAR differed significantly between subjects with and without NAFLD (4.27 vs. 3.26 in men, 7.89 vs. 5.01 in women, respectively, p < .001). Logistic regression analysis determined VAR as a risk factor for NAFLD, and the multivariable-adjusted odds ratios in the highest VAR quartile was 9.57 (95%CI: 5.98-15.30) for men and 12.37 (95%CI: 6.37-24.05) for women. From the receiver operating characteristic analysis, the area under the curve was 0.767 and 0.834, with the suitable cut-off VAR value of 3.469 and 6.357 for men and women, respectively. To control the influence of obesity, all subjects were stratified according to their BMI. For each BMI group, individuals with VAR above the cut-off value had significant higher prevalence and risk of NAFLD, with odds ratios ranging from 1.76 to 4.75.

CONCLUSIONS

Increased VAR is strongly associated with higher risk of NAFLD in both sexes independent of obesity and can serve as a screening reference for NAFLD.

The effect of cinnamon supplementation on liver enzymes in adults: A systematic review and meta-analysis of randomized controlled trials

AIMS

The aim of this study was to perform a systematic review and meta-analysis of randomized controlled trials (RCTs) to examine the effect of cinnamon supplementation on liver enzymes.

METHODS

A systematic search was performed in electronic databases including PubMed-Medline, Scopus, and ISI Web of Science up to November 2020. We used a random effects model to estimate pooled effect size of alanine aminotransferase (ALT), alkaline phosphatase (ALP), and aspartate aminotransferase (AST) levels.

RESULTS

Seven RCTs (9 treatment arms) fulfilled the eligibility criteria of the present meta-analysis. Overall, meta-analysis could not show any beneficial effect of cinnamon supplementation on AST, ALT, and ALP. Subgroup analyses showed that the effect of cinnamon supplementation on ALT was significant at the dosages of <1500 mg/day (Hedges's: -0.61; 95 % CI: -1.11, -0.10; P = 0.002), in trials lasting>12 weeks (Hedges's: -0.83; 95 % CI: -1.36, -0.30; P = 0.01), and in trials conducted of both gender (Hedges's: -0.72; 95 % CI: -1.45, -0.01; P = 0.04).

CONCLUSION

In summary, cinnamon supplementation had no significant effect on liver enzymes in adults. However, the effect of cinnamon on ALT levels was significant at the dosages of <1500 mg/day, in trials lasting>12 weeks, and in trials conducted of both gender. Nevertheless, further studies should be performed to confirm our results.

Implications of Abdominal Adipose Tissue Distribution on Nonalcoholic Fatty Liver Disease and Metabolic Syndrome: A Chinese General Population Study

INTRODUCTION

Visceral adipose tissue (VAT) has been found to play a critical role in the development of metabolic syndrome and nonalcoholic fatty liver disease (NAFLD) independent of generalized obesity.

METHODS

In this secondary study of prospectively acquired data, 625 participants underwent magnetic resonance spectroscopy and chemical shift fat-water separation MRI (2-point Dixon) of the liver and whole abdomen, respectively, in a 3 Tesla magnet. Whole abdominal VAT and subcutaneous adipose tissue (SAT) were extracted from the 2-point Dixon image series using an automated method. Clinical/anthropometric/blood biochemistry parameters were measured. Using region-specific body mass index, participants were classified into 3 paired subgroups (lean, overweight, and obese) and presence of NAFLD (liver fat content ≥ 5.5%).

RESULTS

All relevant clinical/anthropometric/blood biochemistry characteristics and liver enzymes were statistically significant between groups (P < 0.001). NAFLD was found in 12.1%, 43.8%, and 68.3% and metabolic syndrome in 51.1%, 61.9%, and 65% of the lean, overweight, and obese, respectively. Odds ratio for metabolic syndrome and NAFLD was increased by 2.73 (95% confidence interval [CI] 2.18-3.40) and 2.53 (95% CI 2.04-3.12), respectively, for 1SD increase in VAT volume while prevalence of metabolic syndrome was increased by 2.26 (95% CI 1.83-2.79) for 1SD increase in liver fat content (%). VAT/SAT ratio in the lean with fatty liver showed the highest ratio (0.54) among all the subgroups, without a significant difference between the lean and obese with NAFLD (P = 0.127).

DISCUSSION

Increased VAT volume/disproportional distribution of VAT/SAT may be vital drivers to the development of metabolic syndrome and NAFLD irrespective of body mass index category.

The metabolic profiles and body composition of lean metabolic associated fatty liver disease

BACKGROUND/PURPOSE

Metabolic associated fatty liver disease (MAFLD) is the commonest cause of chronic liver disease, which is associated with obesity and diabetes. However, it also occurs in lean individuals especially in Asian populations.

METHODS

The participants of Tzu Chi MAFLD cohort (TCMC) including health controls or MAFLD patients were enrolled. MAFLD was defined as fatty liver in imaging without hepatitis B virus, hepatitis C virus infection, drug, alcohol or other known causes of chronic liver disease. Lean MAFLD was defined as MAFLD in lean subjects (BMI < 23 kg/m²).

RESULTS

A total of 880 subjects were included for final analysis. Of 394 MAFLD patients, 65 (16.5%) patients were diagnosed as lean MAFLD. Lean MAFLD patients were elder, higher percentage of female gender, lower ALT, diastolic blood pressure, triglyceride, and waist circumference but higher HDL than non-lean MAFLD patients. Using binary regression analysis, elder age and lower waist circumference were associated with lean MAFLD. Compared with lean healthy controls, lean MAFLD patients had higher BMI, waist circumference, and percentage of hypertension. In body composition, fatty tissue index (FTI), lean tissue index (LTI) ,and total body water (TBW) were lower in lean MAFLD than non-lean MAFLD patients; but they were comparable with lean healthy controls.

CONCLUSIONS

The prevalence of lean MAFLD was 16.5% in this study population and it was higher in elder age, especially of female subjects. Lean MAFLD patients had different metabolic profiles compared with lean healthy controls, but different body composition compared with non-lean MAFLD patients.

Nonalcoholic Fatty Liver Disease: A Global Perspective

The prevalence of nonalcoholic fatty liver disease (NAFLD) has been increasing over the years and is now as high in Asia as in the Western world, so much so that it should no longer be considered a Western disease. In fact, China is expected to have the largest increase in the number of NAFLD cases in the coming years. The increase in prevalence of NAFLD in Asia lags behind that of the Western world; thus, there will be a lag in more severe liver disease in Asia despite a similar prevalence of the disease. NAFLD is more prevalent among patients with diabetes mellitus, which is also an important risk factor for more severe liver disease. Patients with diabetes mellitus thus represent an important target for screening for NAFLD and more severe liver disease. Although the PNPLA3 gene polymorphism is the most studied in NAFLD, it is increasingly clear that the cumulative effect of multiple genes likely predisposes to NAFLD and more severe liver disease in the different ethnic groups, and polygenic risk scores are emerging. Lean NAFLD has been largely reported in Asia but is increasingly recognized worldwide. Multiple risk factors have been identified for the disease that manifests in metabolically unhealthy normal weight individuals; however, it responds to lifestyle intervention, similar to the disease in obese individuals. Lastly, the newer term "metabolic dysfunction-associated fatty liver disease" provides a more accurate reflection of the disease, giving more focus to clinicians and researchers in tackling this increasingly common and challenging disease.

NAFLD in type 1 diabetes: overrated or underappreciated?

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in western countries, affecting 25-30% of the general population and up to 65% in those with obesity and/or type 2 diabetes. Accumulation of visceral adipose tissue and insulin resistance (IR) contributes to NAFLD. NAFLD is not an innocent entity as it not only may cause nonalcoholic steatohepatitis and cirrhosis but also contribute to cardiovascular morbidity and mortality. More and more people with type 1 diabetes (T1D) are becoming overweight and present with features of IR, but the prevalence and impact of NAFLD in this population are still unclear. The utility of noninvasive screening tools for NAFLD in T1D is being explored. Recent data indicate that based upon ultrasonographic criteria NAFLD is present in 27% (ranging between 19% and 31%) of adults with T1D. Magnetic resonance imaging data indicate a prevalence rate of 8.6% (ranging between 2.1% and 18.6%). There are, however, multiple factors affecting these data, ranging from study design and referral bias to discrepancies in between diagnostic modalities. Individuals with T1D have a 7-fold higher risk of cardiovascular disease (CVD) and cardiovascular mortality is the most prominent cause of death in T1D. Patients with T1D and NALFD are also more prone to develop CVD, but the independent contribution of NAFLD to cardiovascular events has to be determined in this population. Furthermore, limited data in T1D also point towards a 2 to 3 times higher risk for microvascular complications in those with NAFLD. In this article, we will discuss epidemiological and diagnostic challenges of NAFLD in T1D, explore the link between IR and NAFLD and chronic complications, and examine the independent contribution of NAFLD to the presence of macro-, and microvascular complications.