Mediterranean diet and non-alcoholic fatty liver disease: the need of extended and comprehensive interventions

The Role of Antioxidants in the Treatment of Metabolic Dysfunction-Associated Fatty Liver Disease: A Systematic Review

Non-alcoholic fatty liver disease (NAFLD) is a global public health problem that causes liver-related morbidity and mortality. It is also an independent risk factor for non-communicable diseases. In 2020, a proposal was made to refer to it as "metabolic dysfunction-associated fatty liver disease (MAFLD)", with concise diagnostic criteria. Given its widespread occurrence, its treatment is crucial. Increased levels of oxidative stress cause this disease. This review aims to evaluate various studies on antioxidant therapies for patients with MAFLD. A comprehensive search for relevant research was conducted on the PubMed, SCOPUS, and ScienceDirect databases, resulting in the identification of 87 studies that met the inclusion criteria. In total, 31.1% of human studies used natural antioxidants, 53.3% used synthetic antioxidants, and 15.5% used both natural and synthetic antioxidants. In human-based studies, natural antioxidants showed 100% efficacy in the treatment of MAFLD, while synthetic antioxidants showed effective results in only 91% of the investigations. In animal-based research, natural antioxidants were fully effective in the treatment of MAFLD, while synthetic antioxidants demonstrated effectiveness in only 87.8% of the evaluations. In conclusion, antioxidants in their natural form are more helpful for patients with MAFLD, and preserving the correct balance of pro-oxidants and antioxidants is a useful way to monitor antioxidant treatment.

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.

Bariatric Nutritional Intervention in Obese Patients with Compensated Liver Cirrhosis: A Four-Year Prospective Study

BACKGROUND

Obesity and liver cirrhosis represent significant health challenges, often leading to various complications.

AIMS

This prospective study aimed to investigate the impact of a four-year bariatric intervention, focusing on adherence to the Mediterranean Diet, on anthropometric, hematologic, and biochemical parameters in obese patients with compensated liver cirrhosis. Additionally, the study evaluated the concurrent contribution of weight loss to these health indicators.

METHODS

The study involved 62 patients with compensated liver cirrhosis (mean age 65.87 ± 6 years) and 44 healthy controls (mean age 59.11 ± 8 years), all with a BMI > 30 kg/m2. Both groups underwent a weight loss intervention based on the Mediterranean diet, with a four-year follow-up. Anthropometric, biochemical and hematologic parameters were evaluated at several time points during the study and their statistical significance was assessed.

RESULTS

Anthropometric parameters, including weight, BMI, waist and hip circumference, percentage of fat mass, and handgrip strength, exhibited significant improvements (p < 0.05), particularly within the first year of the intervention. Liver function tests and lipid profiles of the patients also showed significant enhancements (p < 0.05). Hematological and biochemical indices, such as hematocrit and ferritin, experienced discreet improvements in the patient cohort (p < 0.05).

CONCLUSIONS

This study highlights the potential of a structured bariatric intervention rooted in the Mediterranean diet to positively influence the health of obese patients with compensated liver cirrhosis. The observed improvements in anthropometric, biochemical, and hematologic parameters, particularly within the first year of the intervention, suggest the importance of dietary modifications in managing the health of this patient population.

Navigating nonalcoholic fatty liver disease (NAFLD): Exploring the roles of estrogens, pharmacological and medical interventions, and life style

The pursuit of studying this subject is driven by the urgency to address the increasing global prevalence of Non-Alcoholic Fatty Liver Disease (NAFLD) and its profound health implications. NAFLD represents a significant public health concern due to its association with metabolic disorders, cardiovascular complications, and the potential progression to more severe conditions like non-alcoholic steatohepatitis (NASH), fibrosis, and cirrhosis. Liver estrogen signaling is important for maintaining liver function, and loss of estrogens increases the likelihood of NAFLD in postmenopausal women. Understanding the multifaceted mechanisms underlying NAFLD pathogenesis, its varied treatment strategies, and their effectiveness is crucial for devising comprehensive and targeted interventions. By unraveling the intricate interplay between genetics, lifestyle, hormonal regulation, and gut microbiota, we can unlock insights into risk stratification, early detection, and personalized therapeutic approaches. Furthermore, investigating the emerging pharmaceutical interventions and dietary modifications offers the potential to revolutionize disease management. This review reinforces the role of collaboration in refining NAFLD comprehension, unveiling novel therapeutic pathways, and ultimately improving patient outcomes for this intricate hepatic condition.

A Study of Dietary Patterns Derived by Cluster Analysis and Their Association With Metabolic Dysfunction-Associated Steatotic Liver Disease Severity Among Hispanic Patients

INTRODUCTION

Diet is a modifiable metabolic dysfunction-associated steatotic liver disease (MASLD) risk factor, but few studies have been conducted among Hispanic patients, despite the fact that MASLD prevalence and severity are highest among this ethnic subgroup. We aimed to identify prevalent dietary patterns among Hispanic patients using cluster analysis and to investigate associations with MASLD severity.

METHODS

This cross-sectional analysis included 421 Harris County MASLD Cohort participants who self-reported Hispanic ethnicity and completed baseline food frequency questionnaires. All included patients had MASLD, diagnosed per standard clinical criteria. K-means analysis was used to identify clusters of patients sharing similar dietary habits. Multivariable adjusted logistic regression was used to estimate associations of dietary clusters with aminotransferases among the overall sample and with histologic steatosis, metabolic dysfunction-associated steatohepatitis, and fibrosis among a subsample of patients who underwent liver biopsy within 6 months of their baseline food frequency questionnaire (n = 186).

RESULTS

We identified 2 clusters: a plant-food/prudent and a fast-food/meat pattern. The fast-food/meat pattern was associated with 2.47-fold increased odds (95% confidence interval 1.31-4.65) of more severe steatosis than the plant-food/prudent pattern after adjusting for demographics, metabolic score, physical activity, and alcohol ( q = 0.0159). No significant association was observed between diet and aminotransferases, metabolic dysfunction-associated steatohepatitis, or fibrosis.

DISCUSSION

Given the importance of sociocultural influences on diet, it is important to understand dietary patterns prevalent among Hispanic patients with MASLD. Using cluster analysis, we identified 1 plant-based pattern vs 1 distinct fast-food/meat-based pattern associated with detrimental effects among our population. This information is an important starting point for tailoring dietary interventions for Hispanic patients with MASLD.

Mediterranean-Oriented Dietary Intervention Is Effective to Reduce Liver Steatosis in Patients with Nonalcoholic Fatty Liver Disease: Results from an Italian Clinical Trial

Results

One hundred and fifty five subjects aged 20-59 years underwent (i) liver ultrasound (US), (ii) clinical and anthropometric evaluations, (iii) blood tests, and (iv) assessment of dietary habits. According to US evaluation, 73 of them had severe, moderate, or mild liver steatosis (NAFLD patients) and 82 had no liver steatosis (healthy controls). Fifty-eight NAFLD patients and 73 controls completed the study. Among NAFLD patients, 26 (45%) downgraded steatosis severity, 12 of which achieved complete steatosis regression (21%). Three of the healthy controls developed NAFLD. The NAFLD patients improved their dietary habits and reduced BMI and waist circumference, during the study period, more than healthy controls. Liver steatosis remission/regression was independent of changes in BMI or liver enzymes and was more frequent among patients with mild steatosis at baseline.

Conclusions

Mediterranean dietary advices, without a personalised meal planning, were efficient in reducing/remitting NAFLD, especially among patients with mild disease, which argues in favour of early identification and lifestyle intervention. This trial is registered with NCT03300661.

Prevalence of non-alcoholic fatty liver disease and its association with lifestyle habits in adults in Chile: a cross-sectional study from the National Health Survey 2016-2017

Non-alcoholic fatty liver disease (NAFLD) represents an excessive fat accumulation within the liver, usually associated with excess body weight. A liver biopsy is the gold standard for diagnosis, but it is inapplicable in population-based studies. In large populations, non-invasive methods could be used, which may also serve to identify potential protective factors. We aimed to (a) estimate NAFLD prevalence in the adult population in Chile by using non-invasive methods and (b) determine the association between the presence of NAFLD and lifestyle habits. The National Health Survey of Chile 2016–2017 was analysed. We included individuals aged 21–75 years, without infectious diseases nor risky alcohol consumption. NAFLD was detected by either fatty liver index (FLI; considers circulating TAG, circulating γ-glutamyl-transferase, BMI and waist circumference), lipid accumulation product (LAP; considers sex, circulating TAG and waist circumference) or their combination. Lifestyle habits were determined by questionnaires. We included 2774 participants, representative of 10 599 094 (9 831 644, 11 366 544) adults in Chile. NAFLD prevalence (95 % CI) was 39·4 % (36·2, 42·8) by FLI, 27·2 % (24·2, 30·4) by LAP and 23·5 % (20·7, 26·5) by their combination. The prevalence progressively increased with increasing BMI. Of note, less smoking and more moderate-vigorous physical activity and whole-grain consumption were associated with lower odds of having NAFLD, independently of BMI. At least one out of four adults in Chile is afflicted with NAFLD. Health promotion strategies focused on controlling excess body weight and promoting specific lifestyle habits are urgently required.

Adherence to Mediterranean Diet: Any Association with NAFLD?

Oxidative stress is considered one of the main determinants in the pathophysiology of non-alcoholic fatty liver disease (NAFLD) and obesity. The alterations of oxidant/antioxidant balance are related to chronic impairment of metabolism leading to mitochondrial dysfunction. Increased oxidative stress also triggers hepatocytes stress pathways, leading to inflammation and contributing to the progression of non-alcoholic steatohepatitis (NASH). Currently, the first-line therapeutic treatment of NAFLD is based on lifestyle interventions, suggesting the Mediterranean Diet (MD) as a preferable nutritional approach due to its antioxidant properties. However, it is still debated if adherence to MD could have a role in determining the risk of developing NAFLD directly or indirectly through its effect on weight. We enrolled 336 subjects (aged 35.87 ± 10.37 years; BMI 31.18 ± 9.66 kg/m²) assessing anthropometric parameters, lifestyle habits, metabolic parameters (fasting plasma glucose, fasting plasma insulin, triglycerides (TG), total cholesterol, low-density (LDL) and high-density lipoprotein (HDL) cholesterol, alanine transaminase (ALT), aspartate aminotransferase (AST), and γ-glutamyltransferase (γGT), cardio-metabolic indices [Homeostatic Model Assessment Insulin Resistance (HoMA-IR), visceral adipose index (VAI) and fatty liver index (FLI)] and adherence to MD [with the PREvención con DIetaMEDiterránea (PREDIMED) questionnaire]. Subjects with NAFLD had significantly higher anthropometric parameters, cardio-metabolic indices and lower adherence to MD than subjects without NAFLD. In a multiple regression analysis, PREDIMED score was the main predictor of FLI (p < 0.001) and came in first, followed by HoMA-IR, while VAI was not a predictor. A PREDIMED score value of <6 could serve as a threshold to identify patients who are more likely to have NAFLD (p < 0.001). In conclusion, high adherence to MD resulted in a lower risk of having NAFLD. Adherence to MD could have a direct role on the risk of developing NAFLD, regardless of visceral adipose tissue.

Practical dietary advices for subjects with alpha-1 antitrypsin deficiency

Congenital alpha-1 antitrypsin deficiency (AATD) is a rare inherited disorder caused by the mutation of the SERPINA1 gene on chromosome 14. At pulmonary level, AAT deficiency leads to an increased risk of chronic obstructive pulmonary disease (COPD) and emphysema, starting from the third-fourth decade of life. At hepatic level, some variants of the allelic, in particular PI*Z, cause a conformational change of the AAT molecule, which polymerizes within the hepatocytes. Excessive hepatic accumulation of these abnormal molecules can lead to liver disease in both adults and children, with clinical presentation ranging from cholestatic jaundice in the newborn to abnormal blood indices of liver function in children and adults, up to fatty liver, cirrhosis and hepatocarcinoma. Nutritional interventions in AATD aim to provide the necessary calories, stop protein catabolism, prevent and treat malnutrition as in the case of common COPD, and even take into account any liver disease that is a distinctive trait, compared to common COPD. Actually, there is a lack of formal research regarding the effects of specific nutritional recommendations in patients with AATD, proper eating habits may help to preserve lung and liver function. For practical dietary advice in patients with AATD and COPD, recently a food pyramid proposal has been published. It has been observed that there is a marked overlap between AATD liver disease and obesity-related liver disease, suggesting shared molecular basis and, therefore, similar nutritional strategies. In this narrative review dietary advice for all possible stages of liver disease have been reported.

Current, emerging, and potential therapies for non-alcoholic steatohepatitis

Non-alcoholic fatty liver disease (NAFLD) has been identified as the most common chronic liver disease worldwide, with a growing incidence. NAFLD is considered the hepatic manifestation of a metabolic syndrome that emerges from multiple factors (e.g., oxidative stress, metabolic disorders, endoplasmic reticulum stress, cell death, and inflammation). Non-alcoholic steatohepatitis (NASH), an advanced form of NAFLD, has been reported to be a leading cause of cirrhosis and hepatic carcinoma, and it is progressing rapidly. Since there is no approved pharmacotherapy for NASH, a considerable number of therapeutic targets have emerged with the deepening of the research on NASH pathogenesis. In this study, the therapeutic potential and properties of regulating metabolism, the gut microbiome, antioxidant, microRNA, inhibiting apoptosis, targeting ferroptosis, and stem cell-based therapy in NASH are reviewed and evaluated. Since the single-drug treatment of NASH is affected by individual heterogeneous responses and side effects, it is imperative to precisely carry out targeted therapy with low toxicity. Lastly, targeted therapeutic agent delivery based on exosomes is proposed in this study, such that drugs with different mechanisms can be incorporated to generate high-efficiency and low-toxicity individualized medicine.

Ellagitannins-Derived Intestinal Microbial Metabolite Urolithin A Ameliorates Fructose-Driven Hepatosteatosis by Suppressing Hepatic Lipid Metabolic Reprogramming and Inducing Lipophagy

Excessive fructose consumption exacerbates the progression of nonalcoholic fatty liver disease (NAFLD) by disrupting hepatic lipid homeostasis. This study sought to evaluate the efficacy of urolithin A (UroA) in a fructose-induced NAFLD mouse model. UroA was administered in the high-fructose-fed mice to investigate the antisteatotic effects in vivo. Fructose-stimulated HepG2 cells and primary hepatocytes were established for in vitro mechanistic assessment. The results suggested that UroA ameliorated fructose-induced hepatic steatosis in mice. Mechanistically, UroA impaired lipogenesis and enhanced β-oxidation in the livers of fructose-fed mice. Notably, UroA facilitated hepatic lipophagy through the AMPK/ULK1 pathway both in vivo and in vitro, degrading lipid droplets for fueling β-oxidation. This study indicates that UroA alleviates excessive lipid accumulation and restores lipid homeostasis in the livers of fructose-fed mice by suppressing lipid metabolic reprogramming and triggering lipophagy. Therefore, dietary supplementation of UroA or ellagitannins-rich foods may be beneficial for NAFLD individuals with high fructose intake.

Nutraceutical approaches to non-alcoholic fatty liver disease (NAFLD): A position paper from the International Lipid Expert Panel (ILEP)

Non-Alcoholic Fatty Liver Disease (NAFLD) is a common condition affecting around 10-25% of the general adult population, 15% of children, and even > 50% of individuals who have type 2 diabetes mellitus. It is a major cause of liver-related morbidity, and cardiovascular (CV) mortality is a common cause of death. In addition to being the initial step of irreversible alterations of the liver parenchyma causing cirrhosis, about 1/6 of those who develop NASH are at risk also developing CV disease (CVD). More recently the acronym MAFLD (Metabolic Associated Fatty Liver Disease) has been preferred by many European and US specialists, providing a clearer message on the metabolic etiology of the disease. The suggestions for the management of NAFLD are like those recommended by guidelines for CVD prevention. In this context, the general approach is to prescribe physical activity and dietary changes the effect weight loss. Lifestyle change in the NAFLD patient has been supplemented in some by the use of nutraceuticals, but the evidence based for these remains uncertain. The aim of this Position Paper was to summarize the clinical evidence relating to the effect of nutraceuticals on NAFLD-related parameters. Our reading of the data is that whilst many nutraceuticals have been studied in relation to NAFLD, none have sufficient evidence to recommend their routine use; robust trials are required to appropriately address efficacy and safety.

The Gut Microbiome and Ferroptosis in MAFLD

Metabolic-associated fatty liver disease (MAFLD) is a new disease definition, and is proposed to replace the previous name, nonalcoholic fatty liver disease (NAFLD). Globally, MAFLD/NAFLD is the most common liver disease, with an incidence rate ranging from 6% to 35% in adult populations. The pathogenesis of MAFLD/NAFLD is closely related to insulin resistance (IR), and the genetic susceptibility to acquired metabolic stress-associated liver injury. Similarly, the gut microbiota in MAFLD/NAFLD is being revaluated by scientists, as the gut and liver influence each other via the gut-liver axis. Ferroptosis is a novel form of programmed cell death caused by iron-dependent lipid peroxidation. Emerging evidence suggests that ferroptosis has a key role in the pathological progression of MAFLD/NAFLD, and inhibition of ferroptosis may become a novel therapeutic strategy for the treatment of NAFLD. This review focuses on the main mechanisms behind the promotion of MAFLD/NAFLD occurrence and development by the intestinal microbiota and ferroptosis. It outlines new strategies to target the intestinal microbiota and ferroptosis to facilitate future MAFLD/NAFLD therapies.

Nutritional intervention in the management of non-alcoholic fatty liver disease

Lifestyle modification is the primary intervention to control NAFLD progression, but despite evidence-based effectiveness it is difficult to distinguish the benefits of nutrition from physical activity and the optimal diet composition is not established. Macronutrients as saturated fatty acids, sugars and animal proteins are harmful in NAFLD and the Mediterranean Diet reducing sugar, red meat and refined carbohydrates and increasing unsaturated-fatty-acids was reported to be beneficial. However one size cannot fit all since NAFLD is a multifaceted syndrome encompassing many diseases of unknown etiologies, different clinical severity and outcomes. Studies of the intestinal metagenome, provided new insights into the physio-pathological interplay between intestinal microbiota and NAFLD. How much the microbiota heterogeneity can influence response to diet remains unknown. New knowledge indicates that AI guided personalized nutrition based on clinic-pathologic and genetic data combined with pre/post nutritional intervention gut metagenomics/metabolomics will be part of the future management of NAFLD.

Comprehensive Review of Cardiovascular Disease Risk in Nonalcoholic Fatty Liver Disease

Nonalcoholic Fatty Liver Disease (NAFLD) is a growing global phenomenon, and its damaging effects in terms of cardiovascular disease (CVD) risk are becoming more apparent. NAFLD is estimated to affect around one quarter of the world population and is often comorbid with other metabolic disorders including diabetes mellitus, hypertension, coronary artery disease, and metabolic syndrome. In this review, we examine the current evidence describing the many ways that NAFLD itself increases CVD risk. We also discuss the emerging and complex biochemical relationship between NAFLD and its common comorbid conditions, and how they coalesce to increase CVD risk. With NAFLD's rising prevalence and deleterious effects on the cardiovascular system, a complete understanding of the disease must be undertaken, as well as effective strategies to prevent and treat its common comorbid conditions.

Modification of dietary patterns in patients with non-alcoholic steatohepatitis

Aim. To assess efficacy of dietary patterns modification with the use of specialized food in patients with non-alcoholic steatohepatitis (NASH). Materials and methods. We developed new specialized food (SPP2) based on literature data on the role of dietary patterns in pathogenesis of NASH. It contained -3 PUFAs, soluble dietary fiber, phospholipids, -lipoic acid, coenzyme Q10, L-carnitine, complex of vitamins. Patients with NASH (per EASL guidelines), were invited to participate in the study and were randomly assigned to receive either isocaloric diet (ICD) alone (based on the results of indirect calorimetry Cosmed, Italy) or isocaloric diet with specialized food (2 portions of SPP2 a day), for 14 days. Repeated examinations of body composition with phase angle analysis (InBody, Republic of Korea) and blood chemistry were performed at baseline (BL) and after 14 days (EOT). The patients were advised to follow usual physical activity during the study. Non-parametric statistics was used to compare BL and EOT characteristics in the groups. Results. The groups did not differ by age, proportion of females, and baseline characteristics of body composition. Adherence to the diet was 87.5% in the ICD group and 88.2% in the ICD+SPP group (p=0.65). Compliance with the use of SPP was 100%. In the ICD+SPP group significant reduction of body weight was achieved (117.530.1 kg initially, vs 114.928.8 kg at EOT; p=0.007), whereas in the ICD group it was not statistically significant (106.722.1 kg at BL vs 104.016.8 kg at EOT, respectively; p=0.07). In contrast to the ICD group, in those who received ICD+SPP significant decrease in cholesterol (5.31.3 mmol/L at BL vs 4.61.3 mmol/L at EOT; p=0.003), LDL (3.71.0 mmol/L vs 3.31.0 mmol/L, respectively; p=0.009), alkaline phosphatase (132.699.1 vs 112.087.0 U/L; p=0.04), GGT (54.533.2 vs 37.519.7 U/L; p=0.04), insulin resistance index (6.13.2 vs 3.21.5, respectively; p=0.04) was detected. Conclusion. Modification of dietary patterns with the use of a specialized food in combination with low-calorie diet allows achieving significant reduction of weight and improve lipid and carbohydrate metabolism, reduce severity of cholestasis in patients with NASH.

Differential Effects of Dietary White Meat and Red Meat on NAFLD Progression by Modulating Gut Microbiota and Metabolites in Rats

Objective. To assess the effects of dietary white meat (grass carp and chicken) and red meat (pork and beef) on metabolic parameters, including the intestinal microbiota and its metabolites (SCFAs and bile acids) in NAFLD rats induced by high-fat diet. Methods. NAFLD rats were randomly assigned to five groups: NAFLD group, grass carp group, chicken group, pork group, and beef group (10 rats in each group), and these rats were fed for 8 weeks using the high-fat diet, grass carp-based diet, chicken-based diet, pork-based diet, and beef-based diet, respectively. At the end of the intervention, NAFLD-related metabolic indexes, intestinal flora, and its metabolites were measured. Results. The grass carp-based diet significantly improved hepatic pathological changes and glycolipid metabolism, and the chicken-based diet only partially improved the metabolic parameters. However, NAFLD progression was observed in the pork group and the beef group. What is more, the white meat-based diet-mediated changes in the enrichment of beneficial bacteria (such as Lactobacillus or Akkermansia), SCFAs, and unconjugated BAs (such as UDCA) and the depletion of pathogenic bacteria (such as Bilophila and Prevotella_9) and conjugated BAs were observed, while the red meat-based diet-induced changes in the enrichment of pathogenic bacteria (Prevotella_9 or Lachnospiraceae_UCG-010) and conjugated BAs and the depletion of SCFAs and unconjugated BAs were found. Conclusion. The dietary white meat and red meat modulating gut microbiota and its metabolites may favor and aggravate NAFLD in rats, respectively.

The impact of health status, diet and lifestyle on non-alcoholic fatty liver disease: Narrative review

Non-alcoholic fatty liver disease (NAFLD) is defined as the abnormal accumulation of triglycerides in the liver. NAFLD has a global prevalence of almost 30%, while incidence is rising with increasing levels of obesity, type 2 diabetes mellitus (T2DM) and metabolic syndrome. Nutrition plays a significant role in both the prevention and treatment of NAFLD. Therefore, the aim of this literature review is to explore the associations between dietary, lifestyle and other risk factors and the risk for developing NAFLD. Dietary patterns, lifestyle behaviours, comorbidities, or a combination of any may contribute to either the progression or prevention of NAFLD. Having diabetes, hypertension, or having obesity might increase the progression of NAFLD if not well treated and controlled. Diet influences the progression of NAFLD; following a western diet or simply a high-fat diet may contribute to the worsening of NAFLD and further progression to non-alcoholic steatohepatitis (NASH) and cirrhosis in later stages. On the other hand, the Mediterranean diet is the gold standard for both the treatment and prevention of NAFLD. Social behaviours, such as smoking, caffeine consumption and physical activity also play a role in the pathophysiology of NAFLD. Nutrition contributes significantly to the prevention or treatment of NAFLD, since this disease can be managed by diet and physical activity. However, further studies are still needed for a better understanding of the mechanisms of action. Randomized control trials are also needed to confirm findings in observational studies.

A Low Glycemic Index Mediterranean Diet Combined with Aerobic Physical Activity Rearranges the Gut Microbiota Signature in NAFLD Patients

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease, and its prevalence worldwide is increasing. Several studies support the pathophysiological role of the gut–liver axis, where specific signal pathways are finely tuned by intestinal microbiota both in the onset and progression of NAFLD. In the present study, we investigate the impact of different lifestyle interventions on the gut microbiota composition in 109 NAFLD patients randomly allocated to six lifestyle intervention groups: Low Glycemic Index Mediterranean Diet (LGIMD), aerobic activity program (ATFIS_1), combined activity program (ATFIS_2), LGIMD plus ATFIS_1 or ATFIS2 and Control Diet based on CREA-AN (INRAN). The relative abundances of microbial taxa at all taxonomic levels were explored in all the intervention groups and used to cluster samples based on a statistical approach, relying both on the discriminant analysis of principal components (DAPCs) and on a linear regression model. Our analyses reveal important differences when physical activity and the Mediterranean diet are merged as treatment and allow us to identify the most statistically significant taxa linked with liver protection. These findings agree with the decreased ‘controlled attenuation parameter’ (CAP) detected in the LGIMD-ATFIS_1 group, measured using FibroScan^®. In conclusion, our study demonstrates the synergistic effect of lifestyle interventions (diet and/or physical activity programs) on the gut microbiota composition in NAFLD patients.

Favorable association between Mediterranean diet (MeD) and DASH with NAFLD among Iranian adults of the Amol Cohort Study (AmolCS)

Nonalcoholic fatty liver disease (NAFLD) is an emerging cause of chronic liver diseases and a major health problem worldwide. Dietary patterns may play a critical role in controlling and preventing this disease, but the available evidence is scarce. The current study aims to ascertain the association of adherence to the Dietary Approach to Stop Hypertension (DASH) diet and Mediterranean diet (MeD) with nonalcoholic fatty liver disease (NAFLD) among Iranian adults of the Amol Cohort Study (AmolCS). In a cross-sectional analysis among 3220 adults (55.3% men), age ≥ 18 years (46.96 ± 14.67), we measured usual dietary intake with a validated food frequency questionnaire (FFQ) and then calculated dietary pattern scores for DASH and MeD. Sociodemographic and lifestyle factors were collected by a structured questionnaire. The presence and degree of NAFLD were also determined by abdominal sonography. Multiple regression models were used to estimate NAFLD odds across tertiles of DASH and Mediterranean dietary scores. Dietary DASH and Mediterranean components were adjusted for total energy intake, based on the residual methods. After adjusting for multiple potential confounders, we found an inverse association of DASH and MeD with NAFLD (Ptrend = 0.02, and Ptrend = 0.002, respectively). Those in the highest tertiles of adherence to the DASH and MeD had the lowest risk for NAFLD (OR = 0.80, 95%CI = 0.66–0.96, OR = 0.64, 95%CI = 0.52–0.78, respectively). The results of logistic analysis of MeD, stratified by gender and abdominal obesity, revealed the favorable association was more pronounced in women (OR = 0.42, 95%CI = 0.29–0.61, Ptrend = 0.004), and in participants with or without abdominal obesity (OR = 0.62, 95% CI = 0.47–0.81, Ptrend = 0.03, OR = 0.64, 95%CI = 0.475–0.91, Ptrend = 0.04, respectively). Similar results were obtained for the adherence to DASH diet score with the prevalence of NAFLD patients with abdominal obesity (OR = 0.75, 95% CI = 0.57–0.97, Ptrend = 0.04). The findings suggested the favorable association between DASH and MeD with NAFLD in Iranian adults, especially women and subjects with or without abdominal obesity. Further prospective investigations are needed to confirm the integrity of our findings.

Mediterranean Diet and Fatty Liver Risk in a Population of Overweight Older Italians: A Propensity Score-Matched Case-Cohort Study

Hepatic steatosis, often known as fatty liver, is the most common hepatic disease in Western countries. The latest guidelines for the treatment of nonalcoholic fatty liver disease emphasize lifestyle measures, such as changing unhealthy eating patterns. Using a propensity score-matching approach, this study investigated the effect of adhering to a Mediterranean diet (MedDiet) on fatty liver risk in an older population (≥65 years) from Southern Italy. We recruited 1.403 subjects (53.6% men, ≥65 years) who completed a food frequency questionnaire (FFQ) and underwent clinical assessment between 2015 and 2018. For the assessment of the liver fat content, we applied the Fatty Liver Index (FLI). To evaluate the treatment effect of the MedDiet, propensity score matching was performed on patients with and without FLI > 60. After propensity score-matching with the MedDiet pattern as treatment, we found a higher consumption of red meat (p = 0.04) and wine (p = 0.04) in subjects with FLI > 60. Based on the FLI, the inverse association shown between adherence to the MedDiet and the risk of hepatic steatosis shows that the MedDiet can help to prevent hepatic steatosis. Consuming less red and processed meat, as well as alcoholic beverages, may be part of these healthy lifestyle recommendations.

Effect of Nutrition Education in NAFLD Patients Undergoing Simultaneous Hyperlipidemia Pharmacotherapy: A Randomized Controlled Trial

BACKGROUND

Patients with non-alcoholic fatty liver disease (NAFLD) have a high prevalence of combined hyperlipidemia. The importance of nutritional education is well-known in NAFLD, but the impact of medical nutrition therapy (MNT) is unclear in patients with NAFLD with hyperlipidemia. The purpose of this study is to investigate the effect of MNT on the improvement of steatohepatitis in patients with NAFLD taking antihyperlipidemic medications.

METHODS

Nondiabetic patients with dyslipidemia were prospectively randomized (1:1) either to the MNT group or the control group with standard advice for 48 weeks with simultaneous statin/ezetimibe combination pharmacotherapy at three tertiary centers in Korea.

RESULTS

Sixty-six patients were enrolled. Among them, 18 patients dropped out and, overall, 48 patients (MNT group 27, control group 21) were prospectively analyzed in the study. The serum ALT level at 48 weeks between the two groups was not significantly different (66.6 ± 37.7 IU/L vs. 57.4 ± 36.7 IU/L, p = 0.40). Serum liver enzymes, controlled attenuation parameter and fibrosis-4 index were significantly improved within the MNT group after 48 weeks compared to baseline. There was no significant difference between the two groups other than the NAFLD fibrosis score (p = 0.017).

CONCLUSIONS

Although there were no significant differences between the two groups in terms of steatosis, metabolic and fibrosis surrogate indicators after 48 weeks, MNT groups showed significant improvement within patient analysis over time. Future studies with a larger number of subjects and a longer study period regarding the effect of MNT are warranted.

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.

The Dietary Inflammatory Index and hepatic health in the US adult population

BACKGROUND

There is limited evidence on the role of an anti-/pro-inflammatory diet in the prevention of non-alcoholic fatty liver disease (NAFLD). We aimed (i) to assess the anti-inflammatory diet profile and its association with transient elastography parameters, including liver stiffness measurement (LSM) and controlled attenuation parameter (CAP), and (ii) to analyse the relationship between the anti-inflammatory diet and surrogate markers of liver disease in a multiethnic US population.

METHODS

A cross-sectional study was conducted on a nationally representative population of 4189 US adults aged 20-80 years. A FibroScan® 502 V2 device (Echosens) was used to estimate the CAP and LSM. Liver markers, including the aspartate transaminase (AST) to alanine transaminase (ALT) ratio, fatty liver index (FLI) and fibrosis-4 score, were also calculated. The Dietary Inflammatory Index (DII) was calculated using a 24-h diet recall.

RESULTS

Lower DII scores (anti-inflammatory diet) were associated with a lower AST:ALT ratio (p < 0.001) and FLI (p < 0.036) after adjusting for covariates. Linear regression analysis revealed that gamma-glutamyl transferase levels (β = 1.702, 95% confidence interval [CI] = 0.325-3.080, p = 0.015), ALT levels (β = -0.616, 95% CI = -1.097 to -0.135, p = 0.012), AST:ALT ratio (β = 0.025, 95% CI = 0.014-0.036, p < 0.001) and FLI (β = 1.168, 95% CI = 0.224-2.112, p = 0.015) were significantly associated with the DII in the multivariable-adjusted model. Participants in the highest anti-inflammatory tertile had the lowest odds ratio (OR) for NAFLD assessed by FLI in both unadjusted (OR = 0.652, 95% CI = 0.539-0.788, p ≤ 0.001) and adjusted models (OR = 0.722, 95% CI = 0.537-0.972, p = 0.032). For the transient elastography parameters (LSM and CAP), no significant associations were identified.

CONCLUSIONS

There was no relationship between the transient elastography parameters and the anti-inflammatory diet profile, although our study showed an association between higher pro-inflammatory properties of diet and poorer hepatic health assessed by surrogate markers of liver disease. Therefore, strategies to promote an anti-inflammatory diet should be considered to prevent NAFLD in adults.

Diet and exercise in NAFLD/NASH: Beyond the obvious

Lifestyle represents the most relevant factor for non-alcoholic fatty liver disease (NAFLD) as the hepatic manifestation of the metabolic syndrome. Although a tremendous body of clinical and preclinical data on the effectiveness of dietary and lifestyle interventions exist, the complexity of this topic makes firm and evidence-based clinical recommendations for nutrition and exercise in NAFLD difficult. The aim of this review is to guide readers through the labyrinth of recent scientific findings on diet and exercise in NAFLD and non-alcoholic steatohepatitis (NASH), summarizing "obvious" findings in a holistic manner and simultaneously highlighting stimulating aspects of clinical and translational research "beyond the obvious". Specifically, the importance of calorie restriction regardless of dietary composition and evidence from low-carbohydrate diets to target the incidence and severity of NAFLD are discussed. The aspect of ketogenesis-potentially achieved via intermittent calorie restriction-seems to be a central aspect of these diets warranting further investigation. Interactions of diet and exercise with the gut microbiota and the individual genetic background need to be comprehensively understood in order to develop personalized dietary concepts and exercise strategies for patients with NAFLD/NASH.

Effect of the Mediterranean diet on histological indicators and imaging tests in non-alcoholic fatty liver disease

AIM

To analyze the scientific evidence regarding to the effect of the Mediterranean diet on the imaging tests and biopsy characteristics in subjects with non-alcoholic fatty liver disease (NAFLD).

METHODS

A bibliographic search was carried out in this narrative review in Pubmed and Web of Science databases, considering studies published between 2011 and 2020, in English or Spanish, randomized clinical trials and observational studies in patients with a diagnosis of NAFLD, in subjects over 18years of age of both sexes.

RESULTS

In the observational studies found, an inverse association between adherence to a Mediterranean diet and liver damage stands out, while in the intervention studies with measurement of liver biopsy a 4.4% reduction in intrahepatic lipids and with magnetic resonance a reduction between 4.2 and 10.2% was found. In experimental studies with ultrasound measurement, the proportion of people with moderate (6-16%) and severe (25%) degree decreased and the studies with transient elastography showed a decrease in liver stiffness between 0.5 and 2.1kPa.

CONCLUSIONS

The Mediterranean diet contributes to the treatment of NAFLD, which is manifested in the liver and histological imaging tests characteristics.

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.

The Impact of Dietary Patterns and Nutrition in Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) has become one of the most common causes of chronic liver disease worldwide. The prevalence of NAFLD has grown proportionally with the rise in obesity, sedentary lifestyle, unhealthy dietary patterns, and metabolic syndrome. Currently, in the absence of approved pharmacologic treatment, the keystone of treatment is lifestyle modification focused on achieving a weight loss of 7%-10%, cardiovascular exercise, and improving insulin sensitivity. The primary aim of this review is to outline the effect of different dietetic approaches against NAFLD and highlight the important micronutrient components in the management of NAFLD.

Gene-Environmental Interactions as Metabolic Drivers of Nonalcoholic Steatohepatitis

Nonalcoholic fatty liver disease (NAFLD) has emerged as a leading cause of chronic liver disease worldwide in the past few decades as a consequence of the global obesity epidemic and is associated with significant morbidity and mortality. NAFLD is closely associated with components of the metabolic syndrome, type 2 diabetes mellitus and cardiovascular disease, suggesting a plausible metabolic mechanistic basis. Metabolic inflexibility is considered a nidus for NAFLD pathogenesis, causing lipotoxicity, mitochondrial dysfunction and cellular stress leading to inflammation, apoptosis and fibrogenesis, thus mediating disease progression into nonalcoholic steatohepatitis (NASH) and ultimately cirrhosis. In this review, we describe they key metabolic drivers that contribute to development of NAFLD and NASH, and we explain how NASH is a metabolic disease. Understanding the metabolic basis of NASH is crucial for the prevention and treatment of this disease.

Nutrition in Chronic Liver Disease: Consensus Statement of the Indian National Association for Study of the Liver

Malnutrition and sarcopenia are common in patients with chronic liver disease and are associated with increased risk of decompensation, infections, wait-list mortality and poorer outcomes after liver transplantation. Assessment of nutritional status and management of malnutrition are therefore essential to improve outcomes in patients with chronic liver disease. This consensus statement of the Indian National Association for Study of the Liver provides a comprehensive review of nutrition in chronic liver disease and gives recommendations for nutritional screening and treatment in specific clinical scenarios of malnutrition in cirrhosis in adults as well as children with chronic liver disease and metabolic disorders.

Possible Hepatoprotective Effect of Tocotrienol-Rich Fraction Vitamin E in Non-alcoholic Fatty Liver Disease in Obese Children and Adolescents

Obesity has become a worldwide health concern among the pediatric population. The prevalence of non-alcoholic fatty liver disease (NAFLD) is growing rapidly, alongside the high prevalence of obesity. NAFLD refers to a multifactorial disorder that includes simple steatosis to non-alcoholic steatohepatitis (NASH) with or devoid of fibrosis. NAFLD is regarded as a systemic disorder that influences glucose, lipid, and energy metabolism with hepatic manifestations. A sedentary lifestyle and poor choice of food remain the major contributors to the disease. Prompt and timely diagnosis of NAFLD among overweight children is crucial to prevent the progression of the condition. Yet, there has been no approved pharmacological treatment for NAFLD in adults or children. As indicated by clinical evidence, lifestyle modification plays a vital role as a primary form of therapy for managing and treating NAFLD. Emphasis is on the significance of caloric restriction, particularly macronutrients (fats, carbohydrates, and proteins) in altering the disease consequences. A growing number of studies are now focusing on establishing a link between vitamins and NAFLD. Different types of vitamin supplements have been shown to be effective in treating NAFLD. In this review, we elaborate on the potential role of vitamin E with a high content of tocotrienol as a therapeutic alternative in treating NAFLD in obese children.

Calorie-Restricted Mediterranean and Low-Fat Diets Affect Fatty Acid Status in Individuals with Nonalcoholic Fatty Liver Disease

Lifestyle modifications are the main support of nonalcoholic fatty liver disease (NAFLD) therapy. Weight loss is one of the primary goals in NAFLD, but the effects of different calorie-restricted diets remain unclear. Thus, we evaluated the effects of two calorie-restricted diets—the Mediterranean diet (Med diet) and low-fat diet—on liver status, cardiometabolic markers, and fatty acid profiles in patients with NAFLD. Twenty-four overweight/moderately obese men were randomly assigned to consume one of these diets. Lipid levels, glucose, insulin, liver enzymes, steatosis, and fatty acid profiles of serum and erythrocytes phospholipids were assessed. After 3 months, all participants had a significant weight loss (>9%), with improvements in waist circumference, body fat %, index of visceral adiposity (VAI), lipid accumulation product, fatty liver (FLI), and hepatic steatosis (HSI) index (p < 0.001). Both diets significantly lowered triglycerides, total and LDL-cholesterol, liver enzymes, fasting glucose, insulin, and HOMA-IR index. Fatty acid profiles were enhanced after both diets, with a significantly decreased n-6/n-3 ratio. Participants on the Med diet had higher levels of HDL-cholesterol and monounsaturated and n-3 docosahexaenoic acids in serum phospholipids and lower levels of saturated fatty acids, triglycerides, TG/HDL ratio, and FLI when compared to participants on the low-fat diet. Our results indicate that dietary patterns and calorie restriction represent central therapeutic issues in the improvement of obesity-related cardiometabolic alterations that are involved in the mechanism of hepatic steatosis. The Med diet may contribute to disease treatment even more than the low-fat diet since it leads to decreased saturated and increased monounsaturated and n-3 polyunsaturated fatty acid status and improved FLI in NAFLD patients.

Prospective association between adherence to the Mediterranean diet and hepatic steatosis: the Swiss CoLaus cohort study

OBJECTIVE

The Mediterranean diet has been promoted as a healthy dietary pattern, but whether the Mediterranean diet may help to prevent hepatic steatosis is not clear. This study aimed to evaluate the prospective association between adherence to the Mediterranean diet and risk of hepatic steatosis.

DESIGN

Population-based prospective cohort study.

SETTING

The Swiss CoLaus Study.

PARTICIPANTS

We evaluated 2288 adults (65.4% women, aged 55.8±10.0 years) without hepatic steatosis at first follow-up in 2009-2012. Adherence to the Mediterranean diet was scaled as the Mediterranean diet score (MDS) based on the Mediterranean diet pyramid ascertained with responses to Food Frequency Questionnaires.

OUTCOME MEASURES

New onset of hepatic steatosis was ascertained by two indices separately: the Fatty Liver Index (FLI, ≥60 points) and the non-alcoholic fatty liver disease (NAFLD) score (≥-0.640 points). Prospective associations between adherence to the Mediterranean diet and risk of hepatic steatosis were quantified using Poisson regression.

RESULTS

During a mean 5.3 years of follow-up, hepatic steatosis was ascertained in 153 (6.7%) participants by FLI criteria and in 208 (9.1%) by NAFLD score. After multivariable adjustment, higher adherence to MDS was associated with lower risk of hepatic steatosis based on FLI: risk ratio 0.84 (95% CI 0.73 to 0.96) per 1 SD of MDS; 0.85 (0.73 to 0.99) adjusted for BMI; and 0.85 (0.71 to 1.02) adjusted for both BMI and waist circumference. When using NAFLD score, no significant association was found between MDS and risk of hepatic steatosis (0.95 (0.83 to 1.09)).

CONCLUSION

A potential role of the Mediterranean diet in the prevention of hepatic steatosis is suggested by the inverse association observed between adherence to the Mediterranean diet and incidence of hepatic steatosis based on the FLI. The inconsistency of this association when hepatic steatosis was assessed by NAFLD score points to the need for accurate population-level assessment of fatty liver and its physiological markers.

Nutritional Approaches for the Management of Nonalcoholic Fatty Liver Disease: An Evidence-Based Review

Nonalcoholic fatty liver disease (NAFLD) is on the rise worldwide representing a public health issue. Its coexistence with obesity and other metabolic alterations is highly frequent. Therefore, current therapy interventions for NAFLD are mainly focused on progressive weight loss through modulation of overall calorie intake with or without specific macronutrient adjustments. Furthermore, other relevant nutritional interventions are built on food selection and time-restricted eating. Since every strategy might bring different results, choosing the optimal diet therapy for a patient is a complicated task, because NAFLD is a multifactorial complex disease. Importantly, some factors need to be considered, such as nutrition-based evidence in terms of hepatic morphophysiological improvements as well as adherence of the patient to the meal plan and adaptability in their cultural context. Thus, the purpose of this review is to explore and compare the subtleties and nuances of the most relevant clinical practice guidelines and the nutritional approaches for the management of NAFLD with a special attention to tangible outcomes and long-term adherence.

ESPEN practical guideline: Clinical nutrition in liver disease

BACKGROUND

The Practical guideline is based on the current scientific ESPEN guideline on Clinical Nutrition in Liver Disease.

METHODS

It has been shortened and transformed into flow charts for easier use in clinical practice. The guideline is dedicated to all professionals including physicians, dieticians, nutritionists and nurses working with patients with chronic liver disease.

RESULTS

A total of 103 statements and recommendations are presented with short commentaries for the nutritional and metabolic management of patients with (i) acute liver failure, (ii) alcoholic steatohepatitis, (iii) non-alcoholic fatty liver disease, (iv) liver cirrhosis, and (v) liver surgery/transplantation. The disease-related recommendations are preceded by general recommendations on the diagnostics of nutritional status in liver patients and on liver complications associated with medical nutrition.

CONCLUSION

This practical guideline gives guidance to health care providers involved in the management of liver disease to offer optimal nutritional care.

A Fad too Far? Dietary Strategies for the Prevention and Treatment of NAFLD

Nonalcoholic fatty liver disease (NAFLD) is a major health problem, and its prevalence has increased in recent years, concurrent with rising rates of obesity and other metabolic diseases. Currently, there are no FDA-approved pharmacological therapies for NAFLD, and lifestyle interventions, including weight loss and exercise, remain the cornerstones for treatment. Manipulating diet composition and eating patterns may be a sustainable approach to NAFLD treatment. Dietary strategies including Paleolithic, ketogenic, Mediterranean, high-protein, plant-based, low-carbohydrate, and intermittent fasting diets have become increasingly popular because of their purported benefits on metabolic disease. This review highlights what is currently known about these popular dietary approaches in the management of NAFLD in clinical populations with mechanistic insight from animal studies. It also identifies key knowledge gaps to better inform future preclinical and clinical studies aimed at the treatment of NAFLD.

Cross-sectional analysis of the health profile and dietary intake of a sample of Canadian adults diagnosed with non-alcoholic fatty liver disease

Background

Dietary intake is an important factor in the development and management of non-alcoholic fatty liver disease (NAFLD); however, optimal dietary composition remains unclear. Moreover, there is minimal evidence on the relationship between dietary intake and markers of liver health in Canadian adults diagnosed with NAFLD.

Objective

The aim of this study is to characterize the dietary intake of a sample of Canadian adults diagnosed with NAFLD and examine the correlations with markers of liver health.

Design

Forty-two adults recruited from the community and hepatology clinics in Calgary, Canada from 2016 to 2019 completed a 3-day food record. Anthropometrics, blood biomarkers, liver stiffness (FibroScan), and liver fat (magnetic resonance imaging) were measured. Nutrient intake was compared with the data from the 2004 and 2015 Canadian Community Health Surveys. Relationships were assessed using Pearson’s correlation and regression analysis.

Results

Relative to Canadian dietary recommendations, participants consumed lower magnesium, fiber, calcium, vitamin D, and vitamin E, and higher cholesterol, saturated fat, total fat, fructose, iron, vitamin B12, selenium, phosphorus, and sodium. Compared with the national average, participants consumed more energy, fiber, sodium, total fat, and saturated fat. Systolic blood pressure (P = 0.012), serum α-2 macroglobulin (P = 0.008), carbohydrate (P = 0.022), total fat (P = 0.029), and saturated fat intakes (P = 0.029) were associated with FibroScan scores. Liver fat was correlated with serum triglycerides (P < 0.001), trunk fat (P = 0.029), added sugar (P = 0.042), phosphorus (P = 0.017), and magnesium intake (P = 0.013). In females, selenium intake was associated with liver fat (P = 0.015) and FibroScan score (P = 0.05), while in males, liver fat was associated with trunk fat (P = 0.004), body weight (P = 0.004), high-density lipoprotein (P < 0.001), and fructose intake (P = 0.037). Regression analysis showed that increasing magnesium intake corresponds to a decrease in liver fat.

Conclusion

Despite the higher energy intake of participants, overall nutrient intake is low, suggesting lower diet quality. Associations between select micronutrients and liver health markers warrant further investigation.

Insights from qualitative research on NAFLD awareness with a cohort of T2DM patients: time to go public with insulin resistance?

BACKGROUND

It is estimated that around 70% of Type 2 Diabetes Mellitus patients (T2DM) have Non-Alcoholic Fatty Liver Disease (NAFLD). Awareness and education are amongst the major shortcomings of the public health response to the increasing threat of NAFLD. Characterizing the specific NAFLD-related information needs of particular high-risk metabolic communities, for instance, T2DM patients, might aid in the development of evidence-based health promotion strategies, ultimately promoting NAFLD-awareness, treatment adherence and therapeutic success rates.

METHODS

Semi-structured interviews with T2DM patients were conducted to gain insight into their awareness of NAFLD, including its relationship with insulin resistance and T2DM.

RESULTS

Awareness of NAFLD as a disease entity, as well as its progression to end-stage liver disease or its relationship with other metabolic conditions, including insulin resistance and T2DM was low. Surveillance behaviours were also suboptimal and perceptions on the self-management knowledge and praxis regarding lifestyle intervention components of T2DM treatment seemed detached from those of NAFLD.

CONCLUSIONS

Our findings could inform the integration of NAFLD-related content in T2DM health promotion strategies. Rising awareness on NAFLD progression and its relationship with T2DM using culturally and community-relevant constructs might facilitate the development of primary and secondary prevention programmes to promote the adherence to lifestyle interventions by influencing NAFLD threat perceptions.

MAFLD: A Consensus-Driven Proposed Nomenclature for Metabolic Associated Fatty Liver Disease

Fatty liver associated with metabolic dysfunction is common, affects a quarter of the population, and has no approved drug therapy. Although pharmacotherapies are in development, response rates appear modest. The heterogeneous pathogenesis of metabolic fatty liver diseases and inaccuracies in terminology and definitions necessitate a reappraisal of nomenclature to inform clinical trial design and drug development. A group of experts sought to integrate current understanding of patient heterogeneity captured under the acronym nonalcoholic fatty liver disease (NAFLD) and provide suggestions on terminology that more accurately reflects pathogenesis and can help in patient stratification for management. Experts reached consensus that NAFLD does not reflect current knowledge, and metabolic (dysfunction) associated fatty liver disease "MAFLD" was suggested as a more appropriate overarching term. This opens the door for efforts from the research community to update the nomenclature and subphenotype the disease to accelerate the translational path to new treatments.

Effects of the Mediterranean diet on cardiovascular risk factors in non-alcoholic fatty liver disease patients: A systematic review and meta-analysis

BACKGROUND & AIMS

We aimed to investigate the effect of the Mediterranean diet (MedDiet) on cardiovascular risk factors in patients with non-alcoholic fatty liver disease (NAFLD).

METHOD

A systematic search was performed in Scopus, Web of Science, Cochrane library and PubMed databases to find randomized controlled trials (RCTs) related to the effect of the MedDiet in patients with NAFLD, up to July, 2019. There was no language and time limitation. Meta-analyses were performed using both the random and fixed effects model where appropriate, and I2 index was used to evaluate the heterogeneity.

RESULTS

Primary search yielded 467 publications. Five RCTs were eligible. Our meta-analysis indicated that the MedDiet resulted in a significant decrease in serum levels of triglyceride and total cholesterol, and a decrease in body weight and HOMA-IR in comparison to a control diet, in NAFLD patients. Whereas, there were no significant improvement in the MedDiet group compared with the control group regarding other variables such as liver enzymes and blood pressure.

CONCLUSIONS

This meta-analysis indicated the advantageous effects of the MedDiet on some cardiovascular risks factors, as compared with a control diet. It seems that the MedDiet can be considered as an appropriate strategy to reduce cardiovascular risk factors in NAFLD patients.

Food groups and the likelihood of non-alcoholic fatty liver disease: a systematic review and meta-analysis

Dietary habits have been implicated in the development and severity of non-alcoholic fatty liver disease (NAFLD). Several epidemiological studies attempted to assess the relationship between food groups and the likelihood of NAFLD, but these results were conflicting. The present meta-analysis was conducted to assess the association between food groups and the likelihood of NAFLD. Published literature was retrieved and screened from MEDLINE, Embase and Web of Science. Out of 7892 retrieved articles, twenty-four observational studies (fifteen cross-sectional studies and nine case–control studies) met our eligibility criteria and were finally included in this systematic review and meta-analysis. Consumption of both red meat and soft drinks contributed to a positive association with NAFLD. Inversely, nut consumption was negatively associated with NAFLD. There were no significant influences on the likelihood of NAFLD about consuming whole grains, refined grains, fish, fruits, vegetables, eggs, dairy products and legumes. This meta-analysis suggests that individuals who consumed more red meat and soft drinks may have a significantly increased likelihood of NAFLD, whereas higher nut intake may be negatively associated with NAFLD. Further prospective studies are required to assess the association between food patterns and NAFLD.

IMPACT OF CURRENT DIET AT THE RISK OF NON-ALCOHOLIC FATTY LIVER DISEASE (NAFLD)

The nonalcoholic fatty liver disease (NAFLD) affects approximately 20%-30% of general population and is even more prevalent among obese individuals. The risk factors mainly associated with NAFLD are diseases related to the metabolic syndrome, genetics and environment. In this review, we provide a literature compilation evaluating the evidence behind dietary components, including calories intake, fat, protein, fibers and carbohydrate, especially fructose which could be a trigger to development and progression of the NAFLD. In fact, it has been demonstrated that diet is an important factor for the development of NAFLD and its association is complex and extends beyond total energy intake.

Effect of weight change and lifestyle modifications on the development or remission of nonalcoholic fatty liver disease: sex-specific analysis

The effects of changes in various lifestyle habits on nonalcoholic fatty liver disease (NAFLD) have not been well elucidated. We aimed to clarify how weight change and lifestyle modifications were associated with the development or remission of NAFLD. In this longitudinal cohort study, we reviewed the periodic health checkup data of 1,421 subjects with no causes of liver disease besides NAFLD who had received at least two health checkups between 2009 and 2018. The prevalence of NAFLD at baseline was 34.1% (484/1,421). During follow-up period (4.6 ± 2.8 years), 104 subjects developed NAFLD and 127 subjects demonstrated NAFLD remission. The frequency of NAFLD development or that of NAFLD remission significantly increased as the larger weight gain or weight loss was, respectively (both, p < 0.001). Approximately 40% of the subjects who maintained ≥ 1%/year weight loss achieved NAFLD remission. By multivariate analysis, quitting smoking were independently associated with NAFLD development (adjusted odds ratio [AOR], 2.86; 95% CI, 1.24–6.62). Subjects who quit smoking demonstrated large weight gain (≥1%/year) significantly more frequently than the other subjects (p < 0.001). In sex-specific analysis, starting to exercise was independently associated with NAFLD remission in men (AOR, 2.38; 95% CI, 1.25–4.53).

Mediterranean Diet and NAFLD: What We Know and Questions That Still Need to Be Answered

Non-alcoholic fatty liver disease (NAFLD) is the hepatic manifestation of metabolic syndrome and is expected to become the leading cause of end-stage liver disease worldwide over the next few decades. In fact, NAFLD encompasses different clinical scenarios, from the simple accumulation of fat (steatosis) to steatohepatitis (NASH), NASH-cirrhosis, and cirrhosis complications. In this context, it is fundamental to pursue strategies aimed at both preventing the disease and reducing the progression of liver fibrosis once liver damage is already initiated. As of today, no pharmacological treatment has been approved for NAFLD/NASH, and the only recommended treatment of proven efficacy are life-style modifications, including diet and physical exercise pointing at weight loss of 5%–7%. Different dietetic approaches have been proposed in this setting, and in this review, we will discuss the evidence regarding the efficacy of the Mediterranean Diet as a treatment for NAFLD. In particular, we will report the effects on liver-related outcomes.

Characterizing specific subgroups in patients with NAFLD: overweight vs obese phenotype

Non-alcoholic fatty liver disease (NAFLD) is increasingly recognized as the most common cause of chronic liver disease worldwide, with a global prevalence of 25.2%. The high burden of NAFLD extends beyond liver diseases, as patients are at risk of developing not only liver related conditions, including cirrhosis and hepatocellular carcinoma, but also cardiovascular complications associated to metabolic syndrome. The present special issue of The Spanish Journal of Gastroenterology (Revista Española de Enfermedades Digestivas) focusses on diverse key aspects of NAFLD, including characterization of fecal microbiota profiles, the role of bariatric endoscopy, evaluation of suitable pre-clinical models for NAFLD or differential epidemiological risk factors associated to NASH and fibrosis.

The effect of a Mediterranean diet on metabolic parameters in patients with non-alcoholic fatty liver disease: A systematic review of randomized controlled trials

BACKGROUND

Dietary habit can play a key role in the prevention and treatment of fatty liver disease (NAFLD). Although many studies have investigated the effect of Mediterranean diet on NAFLD, findings are inconsistent and there is no systematic review on this topic. Therefore, the aim of this systematic review is to summarize the effect of Mediterranean diet on serum metabolic indices and anthropometric measures among NAFLD patients.

METHODS

We searched titles, abstracts, and keywords of articles indexed in Science Direct, MEDLINE, and Google Scholar databases up to October 2018 to identify eligible RCT studies. Randomized clinical trials assessing the effects of MD on NAFLD were included.

RESULTS

The present study included 10 randomized controlled trials, which involved a total of 856 adults with NAFLD. According to the result, MD may improve anthropometric measures, lipid profile, glycemic indices, liver enzyme, and NAFLD severity indices among patients with NAFLD.

CONCLUSION

We found that MD could alleviate NAFLD severity parameters but differences between studies should be taken into account. Finally, in order to draw a firm link between MD and NAFLD, more clinical trials with adequate sample size and better methodology should be done.

Improvements in clinical characteristics of patients with non-alcoholic fatty liver disease, after an intervention based on the Mediterranean lifestyle: a randomised controlled clinical trial

Lifestyle interventions remain the cornerstone therapy for non-alcoholic fatty liver disease (NAFLD). This randomised controlled single-blind clinical trial investigated the effect of Mediterranean diet (MD) or Mediterranean lifestyle, along with weight loss, in NAFLD patients. In all, sixty-three overweight/obese patients (50 (sd 11) years, BMI=31·8 (sd 4·5) kg/m2, 68 % men) with ultrasonography-proven NAFLD (and elevated alanine aminotransferase (ALT) and/or γ-glutamyl transpeptidase (GGT) levels) were randomised to the following groups: (A) control group (CG), (B) Mediterranean diet group (MDG) or (C) Mediterranean lifestyle group (MLG). Participants of MDG and MLG attended seven 60-min group sessions for 6 months, aiming at weight loss and increasing adherence to MD. In the MLG, additional guidance for increasing physical activity and improving sleep habits were given. Patients in CG received only written information for a healthy lifestyle. At the end of 6 months, 88·8 % of participants completed the study. On the basis of intention-to-treat analysis, both MDG and MLG showed greater weight reduction and higher adherence to MD compared with the CG (all P<0·05) at the end of intervention. In addition, MLG increased vigorous exercise compared with the other two study groups (P<0·001) and mid-day rest/naps compared with CG (P=0·04). MLG showed significant improvements in ALT levels (i.e. ALT<40 U/l (P=0·03) and 50 % reduction of ALT levels (P=0·009)) and liver stiffness (P=0·004) compared with CG after adjusting for % weight loss and baseline values. MDG improved only liver stiffness compared with CG (P<0·001) after adjusting for the aforementioned variables. Small changes towards the Mediterranean lifestyle, along with weight loss, can be a treatment option for patients with NAFLD.

Antioxidant Versus Pro-Apoptotic Effects of Mushroom-Enriched Diets on Mitochondria in Liver Disease

Mitochondria play a central role in non-alcoholic fatty liver disease (NAFLD) progression and in the control of cell death signalling during the progression to hepatocellular carcinoma (HCC). Associated with the metabolic syndrome, NAFLD is mostly driven by insulin-resistant white adipose tissue lipolysis that results in an increased hepatic fatty acid influx and the ectopic accumulation of fat in the liver. Upregulation of beta-oxidation as one compensatory mechanism leads to an increase in mitochondrial tricarboxylic acid cycle flux and ATP generation. The progression of NAFLD is associated with alterations in the mitochondrial molecular composition and respiratory capacity, which increases their vulnerability to different stressors, including calcium and pro-inflammatory molecules, which result in an increased generation of reactive oxygen species (ROS) that, altogether, may ultimately lead to mitochondrial dysfunction. This may activate further pro-inflammatory pathways involved in the progression from steatosis to steatohepatitis (NASH). Mushroom-enriched diets, or the administration of their isolated bioactive compounds, have been shown to display beneficial effects on insulin resistance, hepatic steatosis, oxidative stress, and inflammation by regulating nutrient uptake and lipid metabolism as well as modulating the antioxidant activity of the cell. In addition, the gut microbiota has also been described to be modulated by mushroom bioactive molecules, with implications in reducing liver inflammation during NAFLD progression. Dietary mushroom extracts have been reported to have anti-tumorigenic properties and to induce cell-death via the mitochondrial apoptosis pathway. This calls for particular attention to the potential therapeutic properties of these natural compounds which may push the development of novel pharmacological options to treat NASH and HCC. We here review the diverse effects of mushroom-enriched diets in liver disease, emphasizing those effects that are dependent on mitochondria.