The Impact of Macronutrient Intake on Non-alcoholic Fatty Liver Disease (NAFLD): Too Much Fat, Too Much Carbohydrate, or Just Too Many Calories?

Non-alcoholic fatty liver disease (NAFLD) is a growing epidemic, in parallel with the obesity crisis, rapidly becoming one of the commonest causes of chronic liver disease worldwide. Diet and physical activity are important determinants of liver fat accumulation related to insulin resistance, dysfunctional adipose tissue, and secondary impaired lipid storage and/or increased lipolysis. While it is evident that a hypercaloric diet (an overconsumption of calories) promotes liver fat accumulation, it is also clear that the macronutrient composition can modulate this risk. A number of other baseline factors modify the overfeeding response, which may be genetic or environmental. Although it is difficult to disentangle the effects of excess calories vs. specifically the individual effects of excessive carbohydrates and/or fats, isocaloric, and hypercaloric dietary intervention studies have been implemented to provide insight into the effects of different macronutrients, sub-types and their relative balance, on the regulation of liver fat. What has emerged is that different types of fat and carbohydrates differentially influence liver fat accumulation, even when diets are isocaloric. Furthermore, distinct molecular and metabolic pathways mediate the effects of carbohydrates and fat intake on hepatic steatosis. Fat accumulation appears to act through impairments in lipid storage and/or increased lipolysis, whereas carbohydrate consumption has been shown to promote liver fat accumulation through de novo lipogenesis. Effects differ dependent upon carbohydrate and fat type. Saturated fat and fructose induce the greatest increase in intrahepatic triglycerides (IHTG), insulin resistance, and harmful ceramides compared with unsaturated fats, which have been found to be protective. Decreased intake of saturated fats and avoidance of added sugars are therefore the two most important dietary interventions that can lead to a reduction in IHTG and potentially the associated risk of developing type 2 diabetes. A healthy and balanced diet and regular physical activity must remain the cornerstones of effective lifestyle intervention to prevent the development and progression of NAFLD. Considering the sub-type of each macronutrient, in addition to the quantity, are critical determinants of liver health

Ultra-Processed Food Intake Is Associated with Non-Alcoholic Fatty Liver Disease in Adults: A Systematic Review and Meta-Analysis

Non-alcoholic fatty liver disease (NAFLD) is associated with overweight/obesity, metabolic syndrome and type 2 diabetes (T2D) due to chronic caloric excess and physical inactivity. Previous meta-analyses have confirmed associations between ultra-processed food (UPF) intake and obesity and T2D. We aim to ascertain the contribution of UPF consumption to the risk of developing NAFLD. We performed a systematic review and meta-analysis (PROSPERO (CRD42022368763)). All records registered on Ovid Medline and Web of Science were searched from inception until December 2022. Studies that assessed UPF consumption in adults, determined according to the NOVA food classification system, and that reported NAFLD determined by surrogate (steatosis) scores, imaging or liver biopsy were included. The association between UPF consumption and NAFLD was assessed using random-effects meta-analysis methods. Study quality was assessed, and evidence credibility evaluated, using the Newcastle Ottawa Scale and NutriGrade systems, respectively. A total of 5454 records were screened, and 112 records underwent full text review. From these, 9 studies (3 cross-sectional, 3 case-control and 3 cohort), analysing 60,961 individuals, were included in the current review. Both moderate (vs. low) (pooled relative risk 1.03 (1.00–1.07) (p = 0.04) (I2 = 0%)) and high (vs. low) (1.42 (1.16–1.75) (&lt;0.01) (I2 = 89%)) intake of UPF significantly increased the risk of NAFLD. Funnel plots demonstrate low risk of publication bias. Consumption of UPF is associated with NAFLD with a dose–response effect. Public health measures to reduce overconsumption of UPF are imperative to reduce the burden of NAFLD, and the related conditions, obesity and T2D.</jats:p

Ultra‐processed food and non‐communicable diseases in the United Kingdom: A narrative review and thematic synthesis of literature

SummaryThe social and economic constructs of the United Kingdom (UK) provide a fertile food environment for the dramatic expansion in the ultra‐processed food (UPF) market, driving increased UPF consumption. This has coincided with the significant increase in the incidence and prevalence of non‐communicable diseases (NCDs) such as obesity, type 2 diabetes, cardiovascular disease, and cancer, with an inherent impact on morbidity and mortality. Our review aims to assess the current epidemiological and public health trends in the United Kingdom, specifically examining consumption of UPFs and subsequent development of NCDs, summarizing existing meta‐analytical and experimental approaches. First, we address important socioeconomic and psychosocial domains that may contribute to increased availability and consumption of UPF. Additionally, we explore the putative mechanistic basis for the association between UPFs and NCDs: partly attributable to their energy density, the macro‐ and micronutrient composition (including high refined carbohydrate, saturated, and trans fats composition, in addition to low fiber and protein content), and artificially engineered additives and other compounds that adversely affect health in inadequately researched pathophysiological pathways. This review highlights the importance of promoting minimally processed diets to both clinical and political decision makers.</jats:p

Low Screening Rates Despite a High Prevalence of Significant Liver Fibrosis in People with Diabetes from Primary and Secondary Care

Diabetes is a driver of non-alcoholic fatty liver disease (NAFLD) and fibrosis. We determine current practices in examining liver fibrosis in people with diabetes and record prevalence levels in primary and secondary care. We extracted HbA(1c) results ≥48 mmol/mol to identify people with diabetes, then examined the proportion who had AST, ALT, and platelets results, facilitating calculation of non-invasive fibrosis tests (NIT), or an enhanced liver fibrosis score. Fibrosis markers were requested in only 1.49% (390/26,090), of which 29.7% (n = 106) had evidence of significant fibrosis via NIT. All patients at risk of fibrosis had undergone transient elastography (TE), biopsy or imaging. TE and biopsy data showed that 80.6% of people with raised fibrosis markers had confirmed significant fibrosis. We also show that fibrosis levels as detected by NIT are marginally lower in patients treated with newer glucose lowering agents (sodium-glucose transporter protein 2 inhibitors, dipeptidyl peptidase-4 inhibitors and glucagon-like peptide-1 receptor agonists). In conclusion by utilising a large consecutively recruited dataset we demonstrate that liver fibrosis is infrequently screened for in patients with diabetes despite high prevalence rates of advanced fibrosis. This highlights the need for cost-effectiveness analyses to support the incorporation of widespread screening into national guidelines and the requirement for healthcare practitioners to incorporate NAFLD screening into routine diabetes care

Effect of a Low-Calorie Dietary Intervention on Liver Health and Body Weight in Adults with Metabolic-Dysfunction Associated Steatotic Liver Disease (MASLD) and Overweight/Obesity: A Systematic Review and Meta-Analysis

Introduction: Metabolic-dysfunction Associated Steatotic Liver Disease (MASLD) is a common cause of chronic liver disease. This review assessed the efficacy of a Low-Calorie Diet (LCD) on liver health and body weight in people living with MASLD and obesity. Methods: The study was registered with PROSPERO (CRD42021296501), and a literature search was conducted using multiple databases. The key inclusion criteria were randomised controlled trials or cohort studies, obesity/overweight and MASLD. Two authors screened abstracts, reviewed full texts and performed data extraction and quality assessment. The primary outcome was the change in the serum ALT, and secondary outcomes included the changes in the serum AST, intrahepatic lipid content (IHL), quantified non-invasively via MRI/MRS, and body weight. Results: Fifteen studies were included. The LCD reduced body weight by 9.1 kg versus the control (95%CI: −12.4, −5.8) but not serum ALT (−5.9 IU/L, −13.9, 2.0). Total Dietary Replacement (TDR) reduced IHL by −9.1% vs. the control (−15.6%, −2.6%). The Mediterranean-LCD for ≥12 months reduced ALT (−4.1 IU/L, −7.6, −0.5) and for 24 months reduced liver stiffness versus other LCDs. The Green-Mediterranean-LCD reduced IHL, independent of body weight. Limited studies assessed those of Black or Asian ethnicity, and there was heterogeneity in the methods assessing the liver fat content and fibrosis. Conclusions: In people with MASLD and obesity, an LCD intervention reduces IHL and body weight. Trials should focus on the recruitment of Black and Asian ethnicity participants.</jats:p

The impact of non-alcoholic fatty liver disease and liver fibrosis on adverse clinical outcomes and mortality in patients with chronic kidney disease: a prospective cohort study using the UK Biobank

Abstract Background Chronic kidney disease (CKD) and non-alcoholic fatty liver disease (NAFLD) frequently co-exist. We assess the impact of having NAFLD on adverse clinical outcomes and all-cause mortality for people with CKD. Methods A total of 18,073 UK Biobank participants identified to have CKD (eGFR &lt; 60 ml/min/1.73 m2 or albuminuria &gt; 3 mg/mmol) were prospectively followed up by electronic linkage to hospital and death records. Cox-regression estimated the hazard ratios (HR) associated with having NAFLD (elevated hepatic steatosis index or ICD-code) and NAFLD fibrosis (elevated fibrosis-4 (FIB-4) score or NAFLD fibrosis score (NFS)) on cardiovascular events (CVE), progression to end-stage renal disease (ESRD) and all-cause mortality. Results 56.2% of individuals with CKD had NAFLD at baseline, and 3.0% and 7.7% had NAFLD fibrosis according to a FIB-4 &gt; 2.67 and NFS ≥ 0.676, respectively. The median follow-up was 13 years. In univariate analysis, NAFLD was associated with an increased risk of CVE (HR 1.49 [1.38–1.60]), all-cause mortality (HR 1.22 [1.14–1.31]) and ESRD (HR 1.26 [1.02–1.54]). Following multivariable adjustment, NAFLD remained an independent risk factor for CVE overall (HR 1.20 [1.11–1.30], p &lt; 0.0001), but not ACM or ESRD. In univariate analysis, elevated NFS and FIB-4 scores were associated with increased risk of CVE (HR 2.42 [2.09–2.80] and 1.64 [1.30–2.08]) and all-cause mortality (HR 2.82 [2.48–3.21] and 1.82 [1.47–2.24]); the NFS score was also associated with ESRD (HR 5.15 [3.52–7.52]). Following full adjustment, the NFS remained associated with an increased incidence of CVE (HR 1.19 [1.01–1.40]) and all-cause mortality (HR 1.31 [1.13–1.52]). Conclusions In people with CKD, NAFLD is associated with an increased risk of CVE, and the NAFLD fibrosis score is associated with an elevated risk of CVE and worse survival. </jats:sec

Childhood, adolescent, and adulthood adiposity are associated with risk of PCOS: a Mendelian randomization study with meta-analysis.

Study questionWhat is the influence of body composition during childhood, adolescence, and adulthood, as well as metabolic parameters, on incident polycystic ovary syndrome (PCOS)?Summary answerExcess body fat, even during childhood/adolescence, and metabolic parameters, suggestive of hyperinsulinaemia/insulin resistance, significantly impact the risk of PCOS in a linear fashion.What is known alreadyObservational and Mendelian randomization (MR) data have demonstrated an association between adulthood overweight/obesity and development of PCOS. However, the contribution of body composition in childhood/adolescence to incident PCOS is unclear, as is the influence of childhood overweight/obesity.Study design, size, durationWe conducted a systematic review and meta-analysis and integrated our results with a previously published systematic review. Two blinded investigators screened abstracts published between November 2010 and May 2021. Furthermore, we incorporated summary statistics from genome-wide association study (GWAS) data in subjects of European ancestry. Adult overweight was defined as BMI ≥ 25 kg/m2 and obesity as BMI ≥ 30 kg/m2; in Asian subjects, overweight was defined as BMI ≥ 23 kg/m2 and obesity as BMI ≥ 25 kg/m2.Participants/materials, setting, methodsWe utilized meta-analysis and MR together to allow synthesis of genetic and observational data. For the systematic review, the search revealed 71 studies, of which 63 were included in meta-analysis by calculating odds ratios (ORs) using the random-effects model. Furthermore, we conducted a two-sample MR study of GWAS data to determine the impact of childhood and adult body size (defined categorically by BMI and childhood body size proportions), abnormal body composition and metabolic parameters (higher fasting serum insulin or lower sex hormone-binding globulin (SHBG) concentration) on the odds of incident PCOS via the inverse-variance weighted method.Main results and the role of chanceSignificant associations were shown between body composition and PCOS incidence. From the systematic review/meta-analysis, women with overweight (OR 3.80, 2.87-5.03), obesity (OR 4.99, 3.74-6.67), and central obesity (OR 2.93, 2.08-4.12) had increased odds of PCOS. For adolescents with overweight and/or obesity, the PCOS odds were greater than for adults. From MR, for every standard deviation increase in BMI (4.8 kg/m2), the odds of PCOS increased by 2.76 (2.27-3.35). Childhood body size had an independent effect on PCOS odds after adjusting for adult body size (OR: 2.56, 1.57-4.20). Genetically determined body fat percentage (OR 3.05, 2.24-4.15), whole body fat mass (OR 2.53, 2.04-3.14), fasting serum insulin (OR 6.98, 2.02-24.13), and SHBG concentration (OR 0.74, 0.64-0.87) were all significantly associated with PCOS in a linear relation.Limitations, reasons for cautionThe meta-analysis included studies which were cross-sectional and retrospective, limiting our ability to determine causality. MR was limited by interrogating subjects only of European ancestry and including cases classified by either self-diagnosis or diagnostic criteria.Wider implications of the findingsOur study demonstrates for the first time a critical role of the impact of excess childhood/adolescent adiposity on the pathophysiology of adult PCOS. Our results, driven by genetically determined childhood/adolescent body composition, higher BMI, hyperinsulinaemia, and lower SHBG, clearly favour obesity driving the metabolic, but not reproductive, PCOS phenotype. Overall, effective weight maintenance, even from the early years, is likely to reduce the risk of this reproductive endocrine disorder.Study funding/competing interest(s)S.S.Z. was funded by a National Institute for Health and Care Research (NIHR) Academic Clinical Lectureship. U.A. is chair of the NIHR Steering Committee Trial-CASSANDRA-DN. No other authors declare any sources of funding or relevant conflicts of interest. The authors declare that the research was conducted in the absence of any commercial or financial relations that could be construed as a potential conflict of interest.Trial registration numberN/A

Liver fibrosis assessed via non-invasive tests is associated with incident heart failure in a general population cohort.

AimsTo determine whether liver fibrosis is associated with heart failure in a general population cohort, and if genetic polymorphisms (PNPLA3 rs738409; TM6SF2 rs58542926), linked to increased risk of liver fibrosis and decreased risk of coronary artery disease, modify this association.MethodsUsing UK Biobank data, we prospectively examined the relationship between non-invasive fibrosis markers [NAFLD fibrosis score (NFS), Fibrosis-4 (FIB-4) and AST to platelet ratio index (APRI)] and incident hospitalization/death from heart failure (n=413,860). Cox-regression estimated hazard ratios (HR) for incident heart failure. Effects of PNPLA3 and TM6SF2 on the association between liver fibrosis and heart failure were estimated by stratifying for genotype, and testing for an interaction between genotype and liver fibrosis using a likelihood ratio test.Results12,527 incident cases of heart failure occurred over a median of 10.7 years. Liver fibrosis was associated with an increased risk of hospitalization or death from heart failure (multivariable adjusted high risk NFS score HR 1.59 [1.47-1.76], pConclusionIn the general population, serum markers of liver fibrosis are associated with increased hospitalization/death from heart failure. Genetic polymorphisms associated with liver fibrosis were not positively associated with elevated heart failure risk

Ultrasonography in surveillance for hepatocellular carcinoma in patients with non-alcoholic fatty liver disease

International guidelines recommend six monthly ultrasounds as the primary surveillance tool for patients at risk of hepatocellular carcinoma (HCC). The dominant driver of liver disease in HCC surveillance populations is shifting, particularly in Europe and the United States, from chronic viral hepatitis (B or C), towards non-alcoholic fatty liver disease (NAFLD). Today, the population requiring HCC surveillance is also characterised by a high prevalence of overweight/obesity. These patient characteristics significantly impair ultrasound quality which can impede the detection of early HCC lesions. This diagnostic limitation has significant implications considering that eligibility for curative treatment depends upon the stage at which the cancer is detected. In this narrative review, we provide a comprehensive overview of the published evidence and national/international guidelines regarding ultrasound surveillance for HCC in people with NAFLD. We examine ultrasound sensitivity in this cohort for the detection of all stage and early HCC, the impact of steatosis and abdominal obesity on ultrasound performance, evidence for the addition of serum alpha-fetoprotein measurement, optimal timing of surveillance, emerging modalities for risk stratification and screening, and outline the challenges of case finding and surveillance eligibility criteria in this patient cohort. Finally, amalgamating all available evidence, we propose a pragmatic surveillance pathway for patients with NAFLD.</jats:p