Omega-3 fatty acids for the treatment of non-alcoholic fatty liver disease

Unravelling the complexities of non-alcoholic steatohepatitis: The role of metabolism, transporters, and herb-drug interactions

Nonalcoholic fatty liver disease (NAFLD) is a mainstream halting liver disease with high prevalence in North America, Europe, and other world regions. It is an advanced form of NAFLD caused by the amassing of fat in the liver and can progress to the more severe form known as non-alcoholic steatohepatitis (NASH). Until recently, there was no authorized pharmacotherapy reported for NASH, and to improve the patient's metabolic syndrome, the focus is mainly on lifestyle modification, weight loss, ensuring a healthy diet, and increased physical activity; however, the recent approval of Rezdiffra (Resmetirom) by the US FDA may change this narrative. As per the reported studies, there is an increased articulation of uptake and efflux transporters of the liver, including OATP and MRP, in NASH, leading to changes in the drug's pharmacokinetic properties. This increase leads to alterations in the pharmacokinetic properties of drugs. Furthermore, modifications in Cytochrome P450 (CYP) enzymes can have a significant impact on these properties. Xenobiotics are metabolized primarily in the liver and constitute liver enzymes and transporters. This review aims to delve into the role of metabolism, transport, and potential herb-drug interactions in the context of NASH.

G-Protein-Coupled Receptor 120 Agonist Mitigates Steatotic and Fibrotic Features Triggered in Obese Mice by the Administration of a High-Fat and High-Carbohydrate Diet

Nonalcoholic fatty liver disease (NALFD) represents a complex condition ranging from simple steatosis (nonalcoholic fatty liver, NAFL) to inflammation, and fibrosis is one of the main features of nonalcoholic steatohepatitis (NASH). The pathogenesis of NAFLD is not well established but involves several factors (i.e., predisposition of genetic variants, obesity, and unhealthy lifestyle as unbalanced diets) that lead to an alteration of lipid homeostasis and consequently to an abnormal accumulation of triglycerides and other lipids in the liver parenchyma. Currently, no resolutive pharmacological treatment for NAFLD is available, and the only therapeutic approach is a healthy diet and physical exercise. In this study, we investigated the potential beneficial effect of GprA, a new synthetic agonist of G-protein-coupled receptor 120/free fatty acid receptor 4 (GPR120/FFAR4), in the progression of NAFL/NASH in mice fed for different periods (26 weeks and 30 weeks), with a high-fat (40% kcal) and high-carbohydrate diet, also called a Western-style diet (WSD). In our experimental model, the histological, protein, and transcriptomic analyses highlighted that the GprA can reduce signs of steatosis in WSD-fed mice. Furthermore, in 30 week-treated mice, GprA is also effective in the reduction of collagen deposition and fibrosis development. Altogether, our data validate the central role of FFAR4 in the context of NAFL/NASH onset and progression and reveal that GprA could represent an interesting candidate for the development of a new therapeutic approach in NAFLD treatment.

Mapping global research trends: Nutrition associations with nonalcoholic fatty liver disease - a Scopus bibliometric analysis

BACKGROUND

Several bibliometric analyses have been carried out to identify research hotspots and trends in nonalcoholic fatty liver disease (NAFLD) research. Nonetheless, there are still significant knowledge gaps that must be filled to advance our understanding of and ability to treat NAFLD.

AIM

To evaluate, through bibliometric and visual analysis, the current status of related research, related research frontiers, and the developmental trends in the field of diet and NAFLD.

METHODS

We retrieved publications about diet and NAFLD published between 1987 and 2022 from Scopus. Next, we used VOSviewer 1.6.20 to perform bibliometric analysis and visualization.

RESULTS

We found a total of 1905 studies, including 1637 (85.93%) original articles and 195 (10.24%) reviews, focused on the examination of NAFLD and its correlation with diet that were published between 1987 and 2022. Among the remaining five types of documents, 38 were letters, notes, editorials, meeting minutes, or brief surveys, representing 1.99% of the total documents. The countries with the most publications on this topic were China (n = 539; 28.29%), followed by the United States (n = 379; 19.90%), Japan (n = 133; 6.98%), and South Korea (n = 127; 6.6%). According to the citation analysis, the retrieved papers were cited an average of 32.3 times and had an h-index of 106, with 61014 total citations. The two main clusters on the map included those related to: (1) Inflammation and oxidative stress; and (2) Dietary interventions for NAFLD.

CONCLUSION

This was the first study to use data taken from Scopus to visualize network mapping in a novel bibliometric analysis of studies focused on diet and NAFLD. After 2017, the two domains that received the most attention were "dietary interventions for NAFL"' and "'inflammation and oxidative stress implicated in NAFLD and its correlation with diet." We believe that this study provides important information for academics, dietitians, and doctors, and that additional research on dietary interventions and NAFLD is warranted.

The Ameliorating Effects of n-3 Polyunsaturated Fatty Acids on Liver Steatosis Induced by a High-Fat Methionine Choline-Deficient Diet in Mice

The pathogenesis of non-alcoholic fatty liver disease (NAFLD) is associated with abnormalities of liver lipid metabolism. On the contrary, a diet enriched with n-3 polyunsaturated fatty acids (n-3-PUFAs) has been reported to ameliorate the progression of NAFLD. The aim of our study was to investigate the impact of dietary n-3-PUFA enrichment on the development of NAFLD and liver lipidome. Mice were fed for 6 weeks either a high-fat methionine choline-deficient diet (MCD) or standard chow with or without n-3-PUFAs. Liver histology, serum biochemistry, detailed plasma and liver lipidomic analyses, and genome-wide transcriptome analysis were performed. Mice fed an MCD developed histopathological changes characteristic of NAFLD, and these changes were ameliorated with n-3-PUFAs. Simultaneously, n-3-PUFAs decreased serum triacylglycerol and cholesterol concentrations as well as ALT and AST activities. N-3-PUFAs decreased serum concentrations of saturated and monounsaturated free fatty acids (FAs), while increasing serum concentrations of long-chain PUFAs. Furthermore, in the liver, the MCD significantly increased the hepatic triacylglycerol content, while the administration of n-3-PUFAs eliminated this effect. Administration of n-3-PUFAs led to significant beneficial differences in gene expression within biosynthetic pathways of cholesterol, FAs, and pro-inflammatory cytokines (IL-1 and TNF-α). To conclude, n-3-PUFA supplementation appears to represent a promising nutraceutical approach for the restoration of abnormalities in liver lipid metabolism and the prevention and treatment of NAFLD.

Refined mackerel oil increases hepatic lipid accumulation and reduces choline and choline-containing metabolites in the liver tissue in mice fed a Western diet

In this study, we aimed to evaluate the impact of consuming refined mackerel oil (MO) from rest raw material on hepatic fat accumulation, glucose tolerance, and metabolomic changes in the liver from male C57BL/6N mice. The mice were fed either a Western diet (WD) or a chow diet, with 30 g or 60 g MO per kg of diet (3% or 6%) for 13 weeks. Body weight, energy intake, and feed efficiency were monitored throughout the experiment. A glucose tolerance test was conducted after 11 weeks, and metabolomic analyses of the liver were performed at termination. Inclusion of MO in the WD, but not in the chow diet, led to increased liver weight, hepatic lipid accumulation, elevated fasting blood glucose, reduced glucose tolerance, and insulin sensitivity. Hepatic levels of eicosapentaenoic and docosahexaenoic acid increased, but no changes in levels of saturated and monounsaturated fatty acids were observed. The liver metabolomic profile was different between mice fed a WD with or without MO, with a reduction in choline ether lipids, phosphatidylcholines, and sphingomyelins in mice fed MO. This study demonstrates that supplementing the WD, but not the chow diet, with refined MO accelerates accumulation of hepatic fat droplets and negatively affects blood glucose regulation. The detrimental effects of supplementing a WD with MO were accompanied by increased fat digestibility and overall energy intake, and lower levels of choline and choline-containing metabolites in liver tissue.

Effect of fish oil supplementation on the concentration of miRNA-122, FGF-21 and liver fibrosis in patients with NAFLD: Study protocol for a randomized, double-blind and placebo-controlled clinical trial

BACKGROUND & AIMS

To date, no specific drugs are available for non-alcoholic fatty liver disease (NAFLD), though the effect of fish oil supplementation on improving fibrosis in patients with NAFLD has been evaluated. N-3 polyunsaturated fatty acids (n-3 PUFA) may modulate the concentration of microRNAs (miRNAs) and fibroblast growth factor (FGF)-21, which have been identified as non-invasive markers of liver fibrosis. The present study aims to evaluate whether n-3 PUFA supplementation can modulate miRNA-122 and FGF-21 and improve liver fibrosis and steatosis, measured by transient hepatic elastography (THE), in individuals with NAFLD.

METHODS

A randomized, double-blind, placebo-controlled clinical trial will be conducted to evaluate the effect of 4 g/day supplementation of fish oil (2100 mg EPA and 924 mg DHA) in patients with NAFLD over a 6-month period. Fifty-two patients aged >19 years will be randomly assigned to either a placebo (olive oil) or treatment (fish oil) group. Anthropometric data, food intake, physical activity, body composition, resting energy expenditure (evaluated using indirect calorimetry), liver enzymes, platelets, lipids and glucose profile, inflammatory markers (such as C-reactive protein, neutrophil/lymphocyte, platelet/lymphocyte, and monocyte/lymphocyte ratios), miRNA-122 and FGF-21 concentration, and incorporation of fatty acids into the erythrocyte membrane (analyzed using gas chromatography) as well as the degree of liver fibrosis and steatosis assessed using THE (Fibroscan® Touch 502, Paris, France) and liver biomarkers Steato-Brazilian Longitudinal Study of Adult Health, Fatty Liver Index, NAFLD Fibrosis Score, Fibrosis-4 score, and FibroScan-AST score will be evaluated at the beginning and end of the treatment. Continuous variables with normal distribution will be compared between placebo and intervention groups using Student's T test for independent samples; continuous non-parametric variables will be compared using Dunn or Mann-Whitney test. Associations between categorical variables will be analyzed using the chi-square test, and within-group differences will be evaluated using the Wilcoxon signed-ranks test. The criterion for determining significance will be set at 5%.

CONCLUSION

The present study protocol will investigate the supplementation of EPA-rich fish oil as an alternative treatment for NAFLD and its feasibility in affecting the concentration of miRNA-122 and FGF-21 markers. Its findings will offer valuable contributions to the literature.

REGISTRATION

ReBEC number RBR-8dp876.

The interplay between dietary fatty acids and gut microbiota influences host metabolism and hepatic steatosis

Dietary lipids can affect metabolic health through gut microbiota-mediated mechanisms, but the influence of lipid-microbiota interaction on liver steatosis is largely unknown. We investigate the impact of dietary lipids on human gut microbiota composition and the effects of microbiota-lipid interactions on steatosis in male mice. In humans, low intake of saturated fatty acids (SFA) is associated with increased microbial diversity independent of fiber intake. In mice, poorly absorbed dietary long-chain SFA, particularly stearic acid, induce a shift in bile acid profile and improved metabolism and steatosis. These benefits are dependent on the gut microbiota, as they are transmitted by microbial transfer. Diets enriched in polyunsaturated fatty acids are protective against steatosis but have minor influence on the microbiota. In summary, we find that diets enriched in poorly absorbed long-chain SFA modulate gut microbiota profiles independent of fiber intake, and this interaction is relevant to improve metabolism and decrease liver steatosis.

We are what we eat: The role of lipids in metabolic diseases

Lipids play a fundamental role, both structurally and functionally, for the correct functioning of the organism. In the last two decades, they have evolved from molecules involved only in energy storage to compounds that play an important role as components of cell membranes and signaling molecules that regulate cell homeostasis. For this reason, their interest as compounds involved in human health has been gaining weight. Indeed, lipids derived from dietary sources and endogenous biosynthesis are relevant for the pathophysiology of numerous diseases. There exist pathological conditions that are characterized by alterations in lipid metabolism. This is particularly true for metabolic diseases, such as liver steatosis, type 2 diabetes, cancer and cardiovascular diseases. The main issue to be considered is lipid homeostasis. A precise control of fat homeostasis is required for a correct regulation of metabolic pathways and safe and efficient energy storage in adipocytes. When this fails, a deregulation occurs in the maintenance of systemic metabolism. This happens because an increased concentrations of lipids impair cellular homeostasis and disrupt tissue function, giving rise to lipotoxicity. Fat accumulation results in many alterations in the physiology of the affected organs, mainly in metabolic tissues. These alterations include the activation of oxidative and endoplasmic reticulum stress, mitochondrial dysfunction, increased inflammation, accumulation of bioactive molecules and modification of gene expression. In this chapter, we review the main metabolic diseases in which alterations in lipid homeostasis are involved and discuss their pathogenic mechanisms.

Identification of polyunsaturated fatty acids related key modules and genes in metabolic dysfunction-associated fatty liver disease using WGCNA analysis

Polyunsaturated fatty acids (PUFAs) play important roles in the aetiology and pathogenesis of metabolic dysfunction-associated fatty liver disease (MAFLD). However, the underlying molecular mechanisms are not understood. We analysed a public GEO dataset, GSE89632, to identify differentially expressed genes (DEGs) in MAFLD. Weighted gene coexpression network analysis (WGCNA) was used to reveal the core gene regulation network and to explore the PUFA-related hub genes in MAFLD. We experimentally verified these genes by quantitative reverse transcription PCR in high-fat diet (HFD)-fed mice. A total of 286 common DEGs (89 upregulated; 197 downregulated), mostly related to inflammatory and immune responses, were identified. Six modules were constructed using WGCNA, and 2 modules showed significant correlations with PUFAs. After combining these 2 modules with DEGs, the top 10 hub genes were identified. We further established a MAFLD mouse model with liver steatosis, as proved by HE and Oil Red O staining. Of the hub genes, ADAM metallopeptidase with thrombospondin type 1 motif 1 (adamts1) (p = 0.005) and transforming growth factor β3 (tgfβ3) (p < 0.001) showed significantly lower mRNA expression in MAFLD in vivo. adamts1 and tgfβ3 bridged PUFAs and MAFLD, which might be potential causative genes and therapeutic targets of MAFLD.

The association between major dietary patterns with the risk of non-alcoholic fatty liver disease, oxidative stress and metabolic parameters: A case-control study

Purpose

Non-alcoholic fatty liver disease (NAFLD) is caused by the increase of fat in the liver. The present study aimed to study the association between different dietary patterns and NAFLD in adults.

Methods

This study included 121 adult patients with NAFLD and 119 non-NAFLD. Dietary intake was calculated by a 168-item food frequency questionnaire. Biochemical markers were measured. Dietary patterns were determined by factor analysis. The association between dietary patterns and NAFLD was evaluated using multiple logistic regression analysis.

Results

Two dietary patterns (healthy, western) were recognized in participants. Western dietary pattern was related with 72 percent increase in the odds of NAFLD (OR: 1.72; 95% CI: 1.32,2.14), after adjustment for covariates. Healthy dietary pattern was associated with 38 percent lower odds of NAFLD (OR: 0.38; 95% CI: 0.11, 0.65). Adherence to the western diet was related to 0.486 greater amounts of ALT, 3.248 mg/dl higher levels of FBS, and 3.989 mg/dl greater amounts of TG and 2.354 mg/dl greater amounts of MDA after adjusting for confounding factors (p > 0.001, p = 0.042, p > 0.001, p = 0.036 respectively). The healthy dietary pattern score was negatively associated with FBS and Cholesterol and TG levels (p = 0.035, p = 0.048, and p = 0.025), respectively. Moreover, it was associated with 3.211 mg/dl higher levels of TAC (p = 0.049).

Conclusions

There is a significant relationship between dietary patterns and non-alcoholic fatty liver disease. Adherence to a western dietary pattern is related to an increase in non-alcoholic fatty liver disease.

The first study on the effect of crocodile oil from Crocodylus siamensis on hepatic mitochondrial function for energy homeostasis in rats

Background and Aim:

Consumption of fatty acids (FA) can alter hepatic energy metabolism and mitochondrial function in the liver. Crocodile oil (CO) is rich in mono-and polyunsaturated FAs, which have natural anti-inflammatory and healing properties. In rat livers, we investigated the effect of CO on mitochondrial function for energy homeostasis.

Materials and Methods:

Twenty-one male Sprague-Dawley rats were divided into three groups at random. Group 1 rats were given sterile water (RO), Group 2 rats were given CO (3% v/w), and Group 3 rats were given palm oil (PO) (3% v/w). For 7 weeks, rats were given sterile water, CO, and PO orally. The researchers looked at body weight, food intake, liver weight, energy intake, blood lipid profiles, and mitochondria-targeted metabolites in the liver. The liver’s histopathology, mitochondrial architecture, and hydrolase domain containing 3 (HDHD3) protein expression in liver mitochondria were studied.

Results:

Body weight, liver weight, liver index, dietary energy intake, and serum lipid profiles were all unaffected by CO treatment. The CO group consumed significantly less food than the RO group. The CO group also had significantly higher levels of oxaloacetate and malate than the PO group. CO treatment significantly ameliorated hepatic steatosis, as evidenced by a greater decrease in the total surface area of lipid particles than PO treatment. CO administration preserved mitochondrial morphology in the liver by upregulating the energetic maintenance protein HDHD3. Furthermore, chemical-protein interactions revealed that HDHD3 was linked to the energy homeostatic pathway.

Conclusion:

CO may benefit liver function by preserving hepatic mitochondrial architecture and increasing energy metabolic activity.

Nanocarriers for Drug Delivery: An Overview with Emphasis on Vitamin D and K Transportation

Mounting evidence shows that supplementation with vitamin D and K or their analogs induces beneficial effects in various diseases, e.g., osteoarticular, cardiovascular, or carcinogenesis. The use of drugs delivery systems via organic and inorganic nanocarriers increases the bioavailability of vitamins and analogs, enhancing their cellular delivery and effects. The nanotechnology-based dietary supplements and drugs produced by the food and pharmaceutical industries overcome the issues associated with vitamin administration, such as stability, absorption or low bioavailability. Consequently, there is a continuous interest in optimizing the carriers' systems in order to make them more efficient and specific for the targeted tissue. In this pioneer review, we try to circumscribe the most relevant aspects related to nanocarriers for drug delivery, compare different types of nanoparticles for vitamin D and K transportation, and critically address their benefits and disadvantages.

The effect of dietary patterns on non-alcoholic fatty liver disease diagnosed by biopsy or magnetic resonance in adults: a systematic review of randomised controlled trials

Adhering to specific dietary patterns might hold promise as a lifestyle modification treatment of non-alcoholic fatty liver disease (NAFLD). The aim of this systematic review was to examine the effect of dietary patterns on changes in hepatic fat content, liver enzymes and metabolic syndrome components. We searched Pubmed, Embase, CINAHL and Web of Science for randomised controlled trials published in English until April 2020, comparing a specific dietary pattern with no treatment, usual care, or a different diet in adults with NAFLD. Studies were included if NAFLD had been diagnosed using biopsy, magnetic resonance imaging, or proton magnetic resonance spectroscopy. Data from three trials in adults with NAFLD but without diabetes (n = 128; mean age 49.9 ± 5.0 years, range 42-55 years) were included in the qualitative synthesis; across them, risk of bias was considered low, unclear and high for 33%, 38% and 29% of domains, respectively. There was moderate evidence that a low-carbohydrate, compared to a low-calorie diet (-27%, P = 0.008, one study, n = 18) and the Mediterranean, compared to a low-fat, high-carbohydrate diet (-4.4%, P = 0.030, one study, n = 12) result in greater reductions in hepatic fat content, but no such evidence was found for the Fatty Liver in Obesity dietary pattern (based on the principles of the Mediterranean diet), compared to the American Heart Association diet (-0.6%, P = 0.706, one study, n = 98). No between-group differences were reported for other outcomes across studies. A post hoc analysis, including two eligible studies assessing the effect of the Mediterranean, compared to a low-fat diet, irrespective of baseline presence of diabetes, showed strong evidence that the Mediterranean diet reduces hepatic fat content (-4.1%, 95% CI = -5.8 to -2.3, P < 0.001; I² = 0%) and triglyceride concentrations (-16.9 mg/dL, 95% CI = -26.3 to -7.7, P < 0.001; I² = 0%). Well-designed, adequately powered and rigorous randomised controlled trials are needed to provide robust evidence on the effect of these dietary patterns, but also other whole dietary approaches, on NAFLD progression.

Empirically derived dietary pattern and odds of non-alcoholic fatty liver diseases in overweight and obese adults: a case-control study

Background

The prevalence of non-alcoholic fatty liver disease (NAFLD) is rising at an exponential rate throughout the world. Given the confirmed association between nutritional status and NAFLD, this study aimed to investigate the relationship of dietary patterns with NAFLD in overweight and obese adults.

Methods

In this age- and gender-matched case–control study, 115 newly diagnosed cases and 102 control individuals participated. A validated 178-item semi-quantitative food frequency questionnaire was administered to assess the participants' dietary data. Dietary patterns were extracted from 24 predefined food groups by factor analysis. Multivariate logistic regression was run to evaluate the relationship between dietary patterns and NAFLD.

Results

Factor analysis resulted in: “western”, “traditional”, and “snack and sweets” dietary patterns. The NAFLD odds were greater in participants at the highest quintile of the “western” dietary pattern than the lowest quintile (OR: 3.52; 95% CI: 1.64, 8.61). A significant increasing trend was observed in NAFLD odds across increasing quintiles of the “western” dietary pattern (P-trend = 0.01). After adjusting for the potential confounders, this relationship remained significant (OR: 3.30; 95% CI: 1.06–10.27). After full adjustments, NAFLD had no association with “traditional” or “snack and sweets” dietary patterns.

Conclusion

The “western” dietary pattern containing fast food, refined grains, liquid oil, pickles, high-fat dairy, sweet desserts, red meat, tea, and coffee was associated with increased odds of NAFLD. However, further prospective studies are required to establish these results.

Added Fructose in Non-Alcoholic Fatty Liver Disease and in Metabolic Syndrome: A Narrative Review

Non-alcoholic fatty liver disease (NAFLD) represents the most common chronic liver disease and it is considered the hepatic manifestation of metabolic syndrome (MetS). Diet represents the key element in NAFLD and MetS treatment, but some nutrients could play a role in their pathophysiology. Among these, fructose added to foods via high fructose corn syrup (HFCS) and sucrose might participate in NAFLD and MetS onset and progression. Fructose induces de novo lipogenesis (DNL), endoplasmic reticulum stress and liver inflammation, promoting insulin resistance and dyslipidemia. Fructose also reduces fatty acids oxidation through the overproduction of malonyl CoA, favoring steatosis. Furthermore, recent studies suggest changes in intestinal permeability associated with fructose consumption that contribute to the risk of NAFLD and MetS. Finally, alterations in the hunger–satiety mechanism and in the synthesis of uric acid link the fructose intake to weight gain and hypertension, respectively. However, further studies are needed to better evaluate the causal relationship between fructose and metabolic diseases and to develop new therapeutic and preventive strategies against NAFLD and MetS.

Essential Polyunsaturated Fatty Acids in Blood from Patients with and without Catheter-Proven Coronary Artery Disease

Coronary artery disease (CAD) is the leading cause of death worldwide. Statins reduce morbidity and mortality of CAD. Intake of n-3 polyunsaturated fatty acid (n-3 PUFAs), particularly eicosapentaenoic acid (EPA), is associated with reduced morbidity and mortality in patients with CAD. Previous data indicate that a higher conversion of precursor fatty acids (FAs) to arachidonic acid (AA) is associated with increased CAD prevalence. Our study explored the FA composition in blood to assess n-3 PUFA levels from patients with and without CAD. We analyzed blood samples from 273 patients undergoing cardiac catheterization. Patients were stratified according to clinically relevant CAD (n = 192) and those without (n = 81). FA analysis in full blood was performed by gas chromatography. Indicating increased formation of AA from precursors, the ratio of dihomo-gamma-linolenic acid (DGLA) to AA, the delta-5 desaturase index (D5D index) was higher in CAD patients. CAD patients had significantly lower levels of omega-6 polyunsaturated FAs (n-6 PUFA) and n-3 PUFA, particularly EPA, in the blood. Thus, our study supports a role of increased EPA levels for cardioprotection.

Fasting, Nutrition and Weight Loss: An Approach to Refine Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is considered as one of the most common causes of chronic liver disease. It includes a group of conditions associated with fat deposition in liver cells. Also, NAFLD is strongly associated with obesity and insulin resistance (IR). Until now, there is no pharmacological treatment validated for this disease. Fasting, nutritional intervention, and weight loss can be considered the first line in treating hepatic steatosis. This review is based on the scientific evidence showing the results of these interventions in the past years. The results include fasting and nutritional support for NAFLD treatment in humans. In clinical trials and cohort studies, an increase in hepatic fat content was correlated with a weight loss of at least 7% and a diet resembling the Mediterranean diet (MD) improving hepatic biomarkers and histological regression of NAFLD. Fasting is a dietary approach known to improve the lipid profile in healthy and obese populations by decreasing overall cholesterol, triglycerides, LDL, and increasing HDL. Bariatric surgery helps improve liver fat content in patients with serious health problems due to overweight.

Understanding the Role of the Gut Microbiome and Microbial Metabolites in Non-Alcoholic Fatty Liver Disease: Current Evidence and Perspectives

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease worldwide. NAFLD begins as a relatively benign hepatic steatosis which can evolve to non-alcoholic steatohepatitis (NASH); the risk of cirrhosis and hepatocellular carcinoma (HCC) increases when fibrosis is present. NAFLD represents a complex process implicating numerous factors—genetic, metabolic, and dietary—intertwined in a multi-hit etiopathogenetic model. Recent data have highlighted the role of gut dysbiosis, which may render the bowel more permeable, leading to increased free fatty acid absorption, bacterial migration, and a parallel release of toxic bacterial products, lipopolysaccharide (LPS), and proinflammatory cytokines that initiate and sustain inflammation. Although gut dysbiosis is present in each disease stage, there is currently no single microbial signature to distinguish or predict which patients will evolve from NAFLD to NASH and HCC. Using 16S rRNA sequencing, the majority of patients with NAFLD/NASH exhibit increased numbers of Bacteroidetes and differences in the presence of Firmicutes, resulting in a decreased F/B ratio in most studies. They also present an increased proportion of species belonging to Clostridium, Anaerobacter, Streptococcus, Escherichia, and Lactobacillus, whereas Oscillibacter, Flavonifaractor, Odoribacter, and Alistipes spp. are less prominent. In comparison to healthy controls, patients with NASH show a higher abundance of Proteobacteria, Enterobacteriaceae, and Escherichia spp., while Faecalibacterium prausnitzii and Akkermansia muciniphila are diminished. Children with NAFLD/NASH have a decreased proportion of Oscillospira spp. accompanied by an elevated proportion of Dorea, Blautia, Prevotella copri, and Ruminococcus spp. Gut microbiota composition may vary between population groups and different stages of NAFLD, making any conclusive or causative claims about gut microbiota profiles in NAFLD patients challenging. Moreover, various metabolites may be involved in the pathogenesis of NAFLD, such as short-chain fatty acids, lipopolysaccharide, bile acids, choline and trimethylamine-N-oxide, and ammonia. In this review, we summarize the role of the gut microbiome and metabolites in NAFLD pathogenesis, and we discuss potential preventive and therapeutic interventions related to the gut microbiome, such as the administration of probiotics, prebiotics, synbiotics, antibiotics, and bacteriophages, as well as the contribution of bariatric surgery and fecal microbiota transplantation in the therapeutic armamentarium against NAFLD. Larger and longer-term prospective studies, including well-defined cohorts as well as a multi-omics approach, are required to better identify the associations between the gut microbiome, microbial metabolites, and NAFLD occurrence and progression.

Effect of omega-3 supplementation on cardiometabolic indices in diabetic patients with non-alcoholic fatty liver disease: a randomized controlled trial

Background

Patients with non-alcoholic fatty liver disease (NAFLD) as well as type 2 diabetes mellitus (T2DM) are at increased risk for cardiovascular diseases (CVD). Omega-3 supplementation has been proposed as a possible strategy for management of cardiometabolic risk. Cardiometabolic indices can predict and evaluate the cardiometabolic risk.

Aims

We investigated the effect of omega-3 supplementation on accurate and available cardiometabolic indices including atherogenic index of plasma (AIP), Castelli risk index I, Castelli risk index II and atherogenic coefficient (AC) in diabetic patients with NAFLD.

Methods

We conducted a double-blind, randomized controlled trial (RCT) for 12 weeks. From August 2016 to March 2017, the subjects referred to Faghihi hospital in Shiraz, Iran, were recruited. Sixty diabetic patients with NAFLD were randomly assigned into the omega-3 (2000 mg/d omega-3 capsule contained 360 mg/d eicosapentaenoic acid and 240 mg/d docosahexaenoic acid) and the placebo (liquid paraffin) groups using computer-generated random number table.

Results

Omega-3 supplementation compared to the placebo had no significant effect on AIP (− 0.11 ± 0.20 vs. -0.03 ± 0.16; P = 0.11), Castelli risk index I (− 0.25 ± 0.6 vs. -0.07 ± 0.7; P = 0.42), Castelli risk index II (− 0.24 ± 0.5 vs. -0.14 ± 0.5; P = 0.63) and AC (− 0.25 ± 0.6 vs. -0.07 ± 0.7; P = 0.42). After adjusting for confounding factors, the findings remained without change.

Conclusion

Omega-3 supplementation (2000 mg/d) for 12 weeks has no effect on cardiometabolic risk. It seems, higher doses of omega-3 can improve cordiometabolic risk. The trial was registered at Iranian Registry of Clinical Trials IRCT2016102530489N1.

HR-MS Based Untargeted Lipidomics Reveals Characteristic Lipid Signatures of Wilson's Disease

Background and Aims: The diagnosis of Wilson's disease (WD) is challenging by clinical or genetic criteria. A typical early pathological change of WD is the increased liver lipid deposition and lowered serum triglyceride (TG). Therefore, the contents of serum lipids may provide evidence for screening of biomarkers for WD. Methods: 34 WD patients, 31 WD relatives, and 65 normal controls were enrolled in this study. Serum lipidomics data was acquired by an ultra-high-performance liquid chromatography high-resolution mass spectrometry system, and the data were analyzed by multivariate statistical methods. Results: Of all 510 identified lipids, there are 297 differential lipids between the WD and controls, 378 differential lipids between the relatives and controls, and 119 differential lipids between the patients and relatives. In WD, the abundances of most saturated TG were increased, whereas other unsaturated lipids decreased, including phosphatidylcholine (PC), sphingomyelin (SM), lysophosphatidylcholine (LPC), ceramide (Cer), and phosphatidylserine (PS). We also found many serum lipid species may be used as biomarkers for WD. The areas under the receiver operating characteristic curve (AUC) of PS (35:0), PS (38:5), and PS (34:0) were 0.919, 0.843, and 0.907. The AUCs of TG (38:0) and CerG1 (d42:2) were 0.948 and 0.915 and the AUCs of LPC (17:0) and LPC (15:0) were 0.980 and 0.960, respectively. The lipid biomarker panel exhibits good diagnostic performance for WD. The correlation networks were built among the different groups and the potential mechanisms of differential lipids were discussed. Interestingly, similar lipid profile of WD is also found in their relatives, which indicated the changes may also related to the mutation of the ATP7B gene. Conclusions: Lipid deregulation is another important hallmark of WD besides the deposition of copper. Our lipidomic results provide new insights into the diagnostic and therapeutic targets of WD.

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.

Perioperative omega-3 fatty acids for liver surgery: A meta-analysis of randomized controlled trials

INTRODUCTION

The effect of perioperative omega-3 fatty acids for liver surgery remained controversial. We conducted a systematic review and meta-analysis to explore the influence of omega-3 fatty acids versus placebo in patients undergoing liver surgery.

METHODS

We have searched PubMed, EMbase, Web of science, EBSCO, and Cochrane library databases through May 2020, and included randomized controlled trials (RCTs) assessing the effect of omega-3 fatty acids versus placebo for liver surgery. This meta-analysis was performed using the random-effect model.

RESULTS

Five RCTs were included in the meta-analysis. Overall, compared with control group for liver surgery, omega-3 fatty acids were associated with substantially reduced incidence of infection (odd ratio [OR]=0.56; 95% confidence interval [CI] =0.34-0.91; P = .02), but revealed no remarkable influence on complications (OR = 0.60; 95% CI = 0.29-1.24; P = .17), mortality (OR = 0.76; 95% CI = 0.06-9.37; P = .83), liver failure (OR = 0.72; 95% CI = 0.10 to 5.00; P = 0.74), biliary leakage (OR=1.24; 95% CI = 0.41 to 3.76; P = .70), bleeding (OR = 1.76; 95% CI = 0.63-4.95; P = .28), or ileus (OR = 0.39; 95% CI = 0.07-2.05; P = .27).

CONCLUSION

Perioperative omega-3 fatty acids may be beneficial to reduce the incidence of infection after liver surgery.

Relationship between dietary patterns and non-alcoholic fatty liver disease: A systematic review and meta-analysis

BACKGROUND AND AIM

Non-alcoholic fatty liver disease (NAFLD) is one of the most common causes of chronic liver disease. Previous studies have investigated the association between dietary patterns and NAFLD, but their results are contradictory. Therefore, we carried out this meta-analysis to examine the association between dietary patterns and NAFLD.

METHODS

We searched PubMed, Web of Science, Scopus, and Google Scholar databases until November 14, 2019, to identify the observational studies on the association between dietary patterns and NAFLD. We selected three dietary patterns of Western, Prudent, and Mediterranean. A random-effect model was used to compute the summary risk estimates. Odds ratios (ORs) that were reported for fully adjusted models and their confidence intervals (CIs) were extracted for meta-analysis. Heterogeneity between studies was assessed using Cochran's Q- and I² tests. Eighteen articles (n = 24 867 participants) were entered our systematic review and meta-analysis.

RESULTS

We determined that Western dietary patterns (n = 8787 participants) containing high levels of processed food, red meat, high-fat dairy, and refined grains could significantly increase NAFLD (OR = 1.56, CI = 1.27 to 1.92; P ≤ 0.001). However, the Prudent (n = 13 023 participants) (OR = 0.78, CI = 0.71 to 0.85; P ≤ 0.001) and Mediterranean dietary patterns (n = 3057 participants) (OR = 0.77, CI = 0.60 to 0.98; P = 0.41), defined by high intake of fruits, vegetables, whole grains, fish, and olive oil decreased the risk of this disease.

CONCLUSIONS

We found that Western dietary patterns increased the risk of NAFLD by 56%, although the Prudent and Mediterranean dietary patterns reduced the risk of this disease by 22% and 23%, respectively.

Oxidative Stress in Non-alcoholic Fatty Liver Disease. An Updated Mini Review

Non-alcoholic fatty liver disease (NAFLD) is a challenging disease caused by multiple factors, which may partly explain why it remains still orphan of an adequate therapeutic strategy. Herein we focus on the interplay between oxidative stress (OS) and the other causal pathogenetic factors. Different reactive oxygen species (ROS) generators contribute to NAFLD inflammatory and fibrotic progression, which is quite strictly linked to the lipotoxic liver injury from fatty acids and/or a wide variety of their biologically active metabolites in the context of either a two-hit or a (more recent) multiple parallel hits theory. An antioxidant defense system is usually able to protect hepatic cells from damaging effects caused by ROS, including those produced into the gastrointestinal tract, i.e., by-products generated by usual cellular metabolic processes, normal or dysbiotic microbiota, and/or diet through an enhanced gut–liver axis. Oxidative stress originating from the imbalance between ROS generation and antioxidant defenses is under the influence of individual genetic and epigenetic factors as well. Healthy diet and physical activity have been shown to be effective on NAFLD also with antioxidant mechanisms, but compliance to these lifestyles is very low. Among several considered antioxidants, vitamin E has been particularly studied; however, data are still contradictory. Some studies with natural polyphenols proposed for NAFLD prevention and treatment are encouraging. Probiotics, prebiotics, diet, or fecal microbiota transplantation represent new therapeutic approaches targeting the gut microbiota dysbiosis. In the near future, precision medicine taking into consideration genetic or environmental epigenetic risk factors will likely assist in further selecting the treatment that could work best for a specific patient.

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.

Targeting n-3 Polyunsaturated Fatty Acids in Non-Alcoholic Fatty Liver Disease

BACKGROUND

Non-Alcoholic Fatty Liver Disease (NAFLD) is characterized by abnormal hepatic accumulation of triacylglycerides in the absence of alcohol consumption, in association with Oxidative Stress (OS), a pro-inflammatory state and Insulin Resistance (IR), which are attenuated by n-3 long-chain polyunsaturated Fatty Acids (FAs) C20-C22 (LCPUFAs) supplementation. Main causes of NAFLD comprise high caloric intake and a sedentary lifestyle, with high intakes of saturated FAs.

METHODS

The review includes several searches considering the effects of n-3 LCPUFAs in NAFLD in vivo and in vitro models, using the PubMed database from the National Library of Medicine- National Institutes of Health.

RESULT

The LCPUFAs eicosapentaenoic acid (C20:5 n-3, EPA) and docosahexaenoic acid (C22:6 n- 3, DHA) have a positive effect in diminishing liver steatosis, OS, and the levels of aspartate aminotransferase, alanine aminotransferase and pro-inflammatory cytokines, with improvement of insulin sensitivity and adiponectin levels. The molecular pathways described for n-3 LCPUFAs in cellular and animal models and humans include peroxisome proliferator-activated receptor-α activation favouring FA oxidation, diminution of lipogenesis due to sterol responsive element binding protein-1c downregulation and inflammation resolution. Besides, nuclear factor erythroid-2-related factor-2 activation is elicited by n-3 LCPUFA-derived oxidation products producing direct and indirect antioxidant responses, with concomitant anti-fibrogenic action.

CONCLUSION

The discussed effects of n-3 LCPUFA supplementation support its use in NAFLD, although having a limited value in NASH, a contention that may involve n-3 LCPUFA oxygenated derivatives. Clinical trials establishing optimal dosages, intervention times, type of patients and possible synergies with other natural products are needed in future studies.

Meat intake and risk of hepatocellular carcinoma in two large US prospective cohorts of women and men

BACKGROUND

Epidemiological evidence on the associations between meat intake and risk of hepatocellular carcinoma (HCC) was limited and inconsistent.

METHODS

We prospectively examined the association between consumption of meats and meat mutagens with HCC risk using data from the Nurses' Health Study and the Health Professionals Follow-up Study. Cox proportional-hazards regression models were used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) after adjusting for known liver-cancer risk factors.

RESULTS

During up to 32 years of follow-up, we documented 163 incident HCC cases. The HRs of HCC for the highest vs the lowest tertile intake levels were 1.84 (95% CI: 1.16-2.92, Ptrend = 0.04) for processed red meats and 0.61 (95% CI: 0.40-0.91, Ptrend = 0.02) for total white meats. There was a null association between unprocessed red meats and HCC risk (HR = 1.06, 95% CI: 0.68-1.63, Ptrend = 0.85). We found both poultry (HR = 0.60, 95% CI: 0.40-0.90, Ptrend = 0.01) and fish (HR = 0.70, 95% CI: 0.47-1.05, Ptrend = 0.10) were inversely associated with HCC risk. The HR for HCC risk was 0.79 (95% CI: 0.61-1.02) when 1 standard deviation of processed red meats was substituted with an equivalent amount of poultry or fish intake. We also found a suggestive positive association of intake of meat-derived mutagenicity or heterocyclic amines with risk of HCC.

CONCLUSIONS

Processed red meat intake might be associated with higher, whereas poultry or possibly fish intake might be associated with lower, risk of HCC. Replacing processed red meat with poultry or fish might be associated with reduced HCC risk.

Improvement in serum lipids and liver morphology after supplementation of the diet with fish oil is more evident under regular feeding conditions than under high-fat or mixed diets in rats

BACKGROUND

Dietary n- 3 polyunsaturated fatty acids (PUFAs) have a role in preventing cardiovascular and hepatic diseases. However, their effects might differ significantly depending on individual dietary patterns. The aim of the present study was to evaluate the effects of dietary supplementation with ω-3 fatty acids (FA), administered in different schedules, on hepatic and aortic histological structure, lipid profile, and body weight (BW) in male Wistar rats under standard (SD), high-fat diet (HFD) and mixed feeding conditions.

METHODS

PUFA treatment consisted of the administration of 50 mg/kg fish oil (FO) daily by oral gavage. HFD was obtained by adding a suspension of 4% cholesterol, thiouracil and cholic acid to the animals' drinking water. The rats were maintained on the diets for 6 weeks, and different schedules of PUFA administration were used. At 14, 28, and 42 days, the morphology of liver and aortic samples and the levels of total cholesterol (TC), high-density lipoprotein cholesterol (HDL), low-density lipoprotein cholesterol (LDL), and triglycerides (TG) were assessed.

RESULTS

The HFD groups exhibited significant hyperlipidemia and aortic inflammation, with progression to atherogenesis after 6 weeks. Administration of PUFAs slightly attenuated the aortic changes in these groups and reduced the liver's tendency to steatosis. FO-induced metabolic improvement was more evident in SD than in HFD rats. For instance, after the first 2 weeks, SD animals that received PUFAs had significantly increased HDL levels vs. controls (62.375 ± 4.10 vs. 52.625 ± 8.38 mg/dL, P < 0.05), but HFD rats did not, and decreased TG levels were observed exclusively in the SD rats (57.6 ± 4.09 vs. 66 ± 4.69 mg/dL, P < 0.05). After 6 weeks of n- 3 PUFA administration, LDL was significantly lower in the SD rats than in controls (13.67 ± 4.13 vs. 30.83 ± 2.86 mg/dL, P < 0.001), but the decrease in the HFD rats, although significant (49.17 ± 5.85 mg/dL vs. 57.17 ± 4.96 g/dL, P < 0.05), was not as marked. In the mixed-diet groups, administration of 50 mg/kg/day FO for 14 days under SD conditions following 4 weeks of HFD slightly decreased TG (86.625 ± 11.67 vs. 73 ± 4.52 mg/dL, P < 0.05) and increased HDL (45.875 ± 5.28 vs. 56 ± 3.16 mg/dL). However, in these animals, n-3 PUFA administration had no effect on LDL or TC. Administration of half of the above dose failed to improve any biochemical parameters. FO protected against excessive weight gain mainly under SD conditions.

CONCLUSIONS

The results show that FO confers more protection against cardiovascular risk factors (increased LDL and TG, decreased HDL) and liver lipid accumulation when given to rats consuming regular diets than when given to rats consuming a high-fat diet. This argues that priority should be given to consumption of a healthy diet rather than to the use of supplements. The effectiveness of n-3 PUFAs might be reduced in the case of hyperlipidic intake or after consumption of a high-fat diet.

Diet and liver cancer risk: a narrative review of epidemiological evidence

Primary liver cancer is the third leading cause of cancer-related death worldwide. Most patients are diagnosed at late stages with poor prognosis; thus, identification of modifiable risk factors for primary prevention of liver cancer is urgently needed. The well-established risk factors of liver cancer include chronic infection with hepatitis B virus (HBV) or hepatitis C virus (HCV), heavy alcohol consumption, metabolic diseases such as obesity and diabetes, and aflatoxin exposure. However, a large proportion of cancer cases worldwide cannot be explained by current known risk factors. Dietary factors have been suspected as important, but dietary aetiology of liver cancer remains poorly understood. In this review, we summarised and evaluated the observational studies of diet including single nutrients, food and food groups, as well as dietary patterns with the risk of developing liver cancer. Although there are large knowledge gaps between diet and liver cancer risk, current epidemiological evidence supports an important role of diet in liver cancer development. For example, exposure to aflatoxin, heavy alcohol drinking and possibly dairy product (not including yogurt) intake increase, while intake of coffee, fish and tea, light-to-moderate alcohol drinking and several healthy dietary patterns (e.g. Alternative Healthy Eating Index) may decrease liver cancer risk. Future studies with large sample size and accurate diet measurement are warranted and need to consider issues such as the possible aetiological heterogeneity between liver cancer subtypes, the influence of chronic HBV or HCV infection, the high-risk populations (e.g. cirrhosis) and a potential interplay with host gut microbiota or genetic variations.

Combined effect of n-3 fatty acids and phytosterol esters on alleviating hepatic steatosis in non-alcoholic fatty liver disease subjects: a double-blind placebo-controlled clinical trial

The aim of this study was to investigate the combined effect of n-3 fatty acids (EPA and DHA, at an EPA:DHA ratio of 150:500) and phytosterol esters (PS) on non-alcoholic fatty liver disease (NAFLD) patients. We conducted a randomised, double-blind, placebo-controlled trial. Ninety-six NAFLD subjects were randomly assigned to the following groups: the PS group (receiving 3·3 g/d PS); the FO group (receiving 450 mg EPA + 1500 mg DHA/d); the PS + FO combination group (receiving 3·3 g/d PS and 450 mg EPA + 1500 mg DHA/d) and the PO group (a placebo group). The baseline clinical characteristics of the four groups were similar. The primary outcome was liver:spleen attenuation ratio (L:S ratio). The percentage increase in liver–spleen attenuation (≤1) in the PS + FO group was 36 % (P = 0·083), higher than those in the other three groups (PS group, 11 %, P = 0·519; FO group, 18 %, P = 0·071; PO group, 15 %, P = 0·436). Compared with baseline, transforming growth factor-β (TGF-β) was significantly decreased in the three study groups at the end of the trial (PS, P = 0·000; FO, P = 0·002; PS + FO, P = 0·001) and TNF-α was significantly decreased in the FO group (P = 0·036), PS + FO group (P = 0·005) and PO group (P = 0·032) at the end of the intervention. Notably, TGF-β was reduced significantly more in the PS + FO group than in the PO group (P = 0·032). The TAG and total cholesterol levels of the PS + FO group were reduced by 11·57 and 9·55 %, respectively. In conclusion, co-supplementation of PS and EPA + DHA could increase the effectiveness of treatment for hepatic steatosis.

One-Carbon Metabolism and Nonalcoholic Fatty Liver Disease: The Crosstalk between Nutrients, Microbiota, and Genetics

The prevalence of nonalcoholic fatty liver disease (NAFLD) is increasing worldwide. Its etiology includes nutritional, genetic, and lifestyle factors. Several mechanisms may link one-carbon metabolism - the associated metabolic pathways of folate, methionine, and choline - to the onset of NAFLD. In this review, we attempted to assess how choline, folate, methionine, and betaine affect NAFLD development, mainly through their role in the secretion of very low-density lipoproteins (VLDL) from the liver. We also reviewed recent articles that have described the relation between microbiota metabolism and NAFLD progression. Moreover, we describe the effect of single-nucleotide polymorphisms (SNP) in genes related to one-carbon metabolism and disease prevalence. We additionally seek SNP identified by genome-wide associations that may increase the risk of this disease. Even though the evidence available is not entirely consistent, it seems that the concentrations of choline, methionine, folate, and betaine may affect the progression of NAFLD. Since there is no effective therapy for NAFLD, further investigations into the link between nutrition, gut microbiota, genetic factors, and NAFLD are still necessary, with a particular emphasis on methyl donors.

Fatty Acids and Effects on In Vitro and In Vivo Models of Liver Steatosis

BACKGROUND

Fatty liver, or steatosis, is a condition of excess accumulation of lipids, mainly under form of triglycerides (TG), in the liver, and it is the hallmark of non-alcoholic fatty liver disease (NAFLD). NAFLD is the most common liver disorder world-wide and it has frequently been associated with obesity, hyperlipidemia and insulin resistance. Free fatty acids (FA) are the major mediators of hepatic steatosis; patients with NAFLD have elevated levels of circulating FA that correlate with disease severity.

METHODS

Steatosis is a reversible condition that can be resolved with changed behaviors, or that can progress towards more severe liver damages such as steatohepatitis (NASH), fibrosis and cirrhosis. In NAFLD, FA of exogenous or endogenous origin accumulate in the hepatocytes and trigger liver damages. Excess TG are stored in cytosolic lipid droplets (LDs) that are dynamic organelles acting as hubs for lipid metabolism.

RESULTS

In the first part of this review, we briefly reassumed the main classes of FA and their chemical classification as a function of the presence and number of double bonds, their metabolic pathways and effects on human health. Then, we summarized the main genetic and diet-induced animal models of NAFLD, as well as the cellular models of NAFLD.

CONCLUSIONS

In recent years, both the diet-induced animal models of NAFLD as well as the cellular models of NAFLD have found ever more application to investigate the mechanisms involved in NAFLD, and we referred to their advantages and disadvantages.

Enrichment of brain docosahexaenoic acid (DHA) is highly dependent upon the molecular carrier of dietary DHA: lysophosphatidylcholine is more efficient than either phosphatidylcholine or triacylglycerol

Docosahexaenoic acid (DHA) is highly concentrated in the brain, and its deficiency is associated with several neurological disorders including Alzheimer's disease. However, the currently used supplements do not appreciably enrich brain DHA, although they enrich most other tissues. We tested the hypothesis that the ability of the dietary carrier to augment brain DHA depends upon the generation of DHA-lysophosphatidylcholine (LPC), the preferred carrier of DHA across the blood brain barrier. We compared the efficacy of DHA-triacylglycerol (TAG), di-DHA phosphatidylcholine (PC) and DHA-LPC to enrich brain DHA following their gavage to normal rats for 30 days, all at a dose of 10 mg DHA/day. The results show that DHA from TAG, which is released as free DHA or monoacylglycerol during digestion and is absorbed as TAG in chylomicrons, was incorporated preferentially into adipose tissue and heart but not into brain. In contrast, LPC-DHA increased brain DHA by up to 100% but had no effect on adipose tissue. Di-DHA PC, which generates both free DHA and LPC-DHA during the digestion, enriched DHA in brain, as well as in heart and liver. Brain-derived neurotrophic factor was increased by di-DHA PC and DHA-LPC, but not by TAG-DHA, showing that enrichment of brain DHA correlated with its functional effect. We conclude that dietary DHA from TAG or from natural PC (sn-2 position) is not suitable for brain enrichment, whereas DHA from LPC (at either sn-1 or sn-2 position) or from sn-1 position of PC efficiently enriches the brain and is functionally effective.

A Lipidomic Analysis of Docosahexaenoic Acid (22:6, ω3) Mediated Attenuation of Western Diet Induced Nonalcoholic Steatohepatitis in Male Ldlr -/- Mice

Nonalcoholic fatty liver disease (NAFLD) is a major public health problem worldwide. NAFLD ranges in severity from benign steatosis to nonalcoholic steatohepatitis (NASH), cirrhosis, and primary hepatocellular cancer (HCC). Obesity and type 2 diabetes mellitus (T2DM) are strongly associated with NAFLD, and the western diet (WD) is a major contributor to the onset and progression of these chronic diseases. Our aim was to use a lipidomic approach to identify potential lipid mediators of diet-induced NASH. We previously used a preclinical mouse (low density lipoprotein receptor null mouse, Ldlr -/-) model to assess transcriptomic mechanisms linked to WD-induced NASH and docosahexaenoic acid (DHA, 22:6, ω3)-mediated remission of NASH. This report used livers from the previous study to carry out ultra-high-performance liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) and high-performance liquid chromatography coupled with dynamic multi-reaction monitoring (HPLC-dMRM) to assess the impact of the WD and DHA on hepatic membrane lipid and oxylipin composition, respectively. Feeding mice the WD increased hepatic saturated and monounsaturated fatty acids and arachidonic acid (ARA, 20:4, ω6) in membrane lipids and suppressed ω3 polyunsaturated fatty acids (PUFA) in membrane lipids and ω3 PUFA-derived anti-inflammatory oxylipins. Supplementing the WD with DHA lowered hepatic ARA in membrane lipids and ARA-derived oxylipins and significantly increased hepatic DHA and its metabolites in membrane lipids, as well as C20-22 ω3 PUFA-derived oxylipins. NASH markers of inflammation and fibrosis were inversely associated with hepatic C20-22 ω3 PUFA-derived Cyp2C- and Cyp2J-generated anti-inflammatory oxylipins (false discovery rate adjusted p-value; q ≤ 0.026). Our findings suggest that dietary DHA promoted partial remission of WD-induced NASH, at least in part, by lowering hepatic pro-inflammatory oxylipins derived from ARA and increasing hepatic anti-inflammatory oxylipins derived from C20-22 ω3 PUFA.

High-Fat Feeding in Time-Dependent Manner Affects Metabolic Routes Leading to Nervonic Acid Synthesis in NAFLD

Nonalcoholic fatty liver disease (NAFLD) is characterized by excessive lipid accumulation in the liver. The disturbances in the fatty acid composition of stored lipids are more important than the lipid species itself, which may influence the overall effect caused by these molecules. Thus, uncovering time-dependent changes in the fatty acid composition of accumulated lipid fractions after a high fat diet seems to be a new marker of NAFLD occurrence. The experiments were conducted on high fat fed Wistar rats. The blood and liver samples were collected at the end of each experimental week and used to assess the content of lipid fractions and their fatty acid composition by gas liquid chromatography. The expression of proteins from lipid metabolism pathways and of fatty acid exporting proteins were detected by Western blotting. In the same high fat feeding period, decreased de novo lipogenesis, increased β-oxidation and lipid efflux were demonstrated. The observed effects may be the first liver protective mechanisms against lipotoxicity. Nevertheless, such effects were still not sufficient to prevent the liver from proinflammatory lipid accumulation. Moreover, the changes in liver metabolic pathways caused the plasma nervonic acid concentration in sphingomyelin to decrease simultaneously with NAFLD development, which may be a steatosis occurrence prognostic marker.

Intermediary effect of inflammation on the association between dietary patterns and non-alcoholic fatty liver disease

OBJECTIVE

Previous studies have demonstrated that nutritional status is associated with non-alcoholic fatty liver disease (NAFLD). Meanwhile, subclinical inflammation is associated with the prevalence of NAFLD. To our knowledge, however, no study has investigated the intermediary effect of inflammation on the association between dietary pattern and NAFLD. Thus, the aim of this case-control study was to explore the intermediary effect of inflammation on the association between dietary patterns and NAFLD.

METHODS

Using the propensity score matching method, we generated 2043 cases and 2043 controls. Dietary intake was assessed using a valid self-administered food frequency questionnaire. Major dietary patterns in the population were derived by factor analysis. Reduced rank regression with leukocyte count as a response variable was used to derive an inflammatory pattern. NAFLD was diagnosed by liver ultrasonography and drinking history. The association between dietary patterns and NAFLD was tested using multiple conditional logistic regression analysis.

RESULTS

Three major dietary patterns were derived by factor analysis: sweet pattern, animal foods pattern, and traditional pattern. Compared with participants in the lowest quartile of the animal foods pattern, the odds ratio (OR; 95% confidence interval [CI]) of NAFLD in the highest quartile was 1.30 (95% CI, 1.09-1.55). After adjustment of inflammation status, the OR was weaker (OR, 1.23; 95% CI, 1.03-1.48), albeit significant. Compared with the participants in the lowest quartile of inflammatory pattern, the OR of NAFLD in the highest quartile was 1.52 (95% CI, 1.28-1.81).

CONCLUSION

The present data suggested that inflammation may mediate the association between dietary patterns and NAFLD.

Association Between Index of Nutritional Quality and Nonalcoholic Fatty Liver Disease: The Role of Vitamin D and B Group

BACKGROUND

Numerous studies have revealed that diet has been considered as an important pathogenic factor for nonalcoholic fatty liver disease (NAFLD). The Index of Nutritional Quality (INQ) is a method of quantitative and qualitative evaluation of single foods and diets, which has special significance in recognizing clinical nutritional problems.

MATERIALS AND METHODS

This study included 295 patients with NAFLD and 704 controls. The dietary intake was assessed through a valid and reliable food frequency questionnaire. INQ was calculated from the questionnaire data and was compared between the 2 groups.

RESULTS

The controls had higher INQ of vitamin D, vitamin E, thiamin, riboflavin, niacin, vitamin B12; biotin, pantothenic acid, magnesium and zinc compared to the patients with NAFLD. After controlling for several covariates, positive associations were observed between NAFLD risk and INQs of riboflavin (OR_riboflavin = 0.49, 95% confidence interval [CI]: 0.28-0.78; OR_biotin = 0.35, 95% CI: 0.18-0.76; OR_pantothenic = 0.28, 95% CI: 0.12-0.64; OR_magnesium = 0.28, 95% CI: 0.11-0.75; OR_zinc = 0.15 95% CI: 0.05-0.42).

CONCLUSIONS

Findings of the present study suggest that subjects who follow a more healthy and nutrient-rich diet, especially in terms of vitamins D, B1, B2, B12, B3 and zinc, are at a lower risk of NAFLD compared to those who consume unhealthy and nutrient-poor diet.

Fish oil alleviates circadian bile composition dysregulation in male mice with NAFLD

Our previous studies have found that fish oil rich in ω-3 polyunsaturated fatty acids (ω-3 PUFA) protects against non-alcoholic fatty liver disease (NAFLD) in mice. This study was aimed to explore the effects of fish oil on high fat diet (HFD)-induced circadian bile composition chaos. Male C57BL/6 mice were randomly divided into three groups, a control group (CON), a HFD group and a fish oil (FO) group, which were fed a normal chow diet, a HFD, and a HFD supplemented with FO, respectively for 12 weeks. At the end of the experiment, liver tissue, blood and bile samples were processed at 12-h intervals with the first one at zeitgeber time 0 (ZT0) and the second at zeitgeber time 12 (ZT12). Metabolites in bile were determined using UPLC-QTOF-MS, screened using multivariate statistical analysis, and analyzed using KEGG database and Metaboanalyst. The expression levels of key proteins in bile acid metabolism were examined using western blot. Results of biochemical analysis and H&E staining illustrated that feeding of HFD induced NAFLD, which was ameliorated in FO group. The bile content of each group at ZT0 (CON, HFD, or FO group) was respectively higher than that at ZT12 (P<.05). The metabolic pathway analysis of differential metabolites showed that these differences were correlated with amino acid metabolism, fatty acid biosynthesis and primary bile acid synthesis at ZT0. FO supplement could modify bile composition, which was related to the influence of its ω-3 PUFA on liver metabolism. ω-3 PUFA may also regulate the circadian rhythm of bile metabolism.

A six-months study on Black Soldier Fly (Hermetia illucens) based diets in zebrafish

Intensive fish farming relies on the use of feeds based on fish meal and oil as optimal ingredients; however, further development of the aquaculture sector needs new, nutritious and sustainable ingredients. According to the concept of circular economy, insects represent good candidates as aquafeed ingredients since they can be cultured through environmental-friendly, cost-effective farming processes, on by-products/wastes, and many studies have recently been published about their inclusion in fish feed. However, information about the physiological effects of insect-based diets over the whole life cycle of fish is presently missing. At this regard, the present study investigated, for the first time, the effects of Black Soldier Fly based diets (25 and 50% fish meal substitution) administration for a six months period in zebrafish (Danio rerio), from larvae to adults. A multidisciplinary approach, including biometric, biochemical, histological, spectroscopic and molecular analyses was applied. Aside a general reduction in fish growth and lipid steatosis, six-months feeding on Black Soldier Fly based diets did not show major negative effects on zebrafish. Gut histological analysis on intestine samples did not show signs of inflammation and both stress markers and immune response markers did not show significant differences among the experimental groups.

Dietary Docosahexaenoic Acid (DHA) and Eicosapentaenoic Acid (EPA) Operate by Different Mechanisms to Modulate Hepatic Steatosis and Hyperinsulemia in fa/fa Zucker Rats

Hepatic steatosis, an early stage of non-alcoholic fatty liver disease, is commonly present in obesity and type 2 diabetes, and is associated with reduced hepatic omega-3 polyunsaturated fatty acid (n3-PUFA) status that impacts on the anti-inflammatory and insulin sensitizing functions of n3-PUFA. Our objective was to directly compare plant- and marine-based n3-PUFA (α-linoleic acid (ALA)), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA)) for their effects on hepatic steatosis, markers of hepatic inflammation and fibrosis, and insulinemia in obese rats. Fa/fa Zucker rats were provided diets containing ALA, EPA, DHA, or linoleic acid (LA, n6-PUFA) for eight weeks and compared to baseline fa/fa rats and lean Zucker rats fed LA-rich diet for eight weeks. Both DHA and EPA groups had liver lipid similar to baseline, however, DHA was more effective than EPA for reducing hepatic fatty acid synthase (FAS), increasing the proportion of smaller lipid droplets, reversing early fibrotic damage, and reducing fasting hyperinsulinemia. EPA was more effective for reducing FoxO1. Dietary ALA did not attenuate hepatic steatosis, most inflammatory markers or FAS. In summary, amongst the n3-PUFA, DHA was the most effective for elevating hepatic DHA levels, and preventing progression of hepatic steatosis via reductions in FAS and a marker of fibrosis.

Effect of Fish Oil Supplementation on Hepatic and Visceral Fat in Overweight Men: A Randomized Controlled Trial

Being overweight increases the risk of the development of metabolic conditions such as non-alcoholic fatty liver disease (NAFLD), which is itself an independent predictor of cardiovascular disease. Omega-3 polyunsaturated fatty acid (PUFA) supplementation is recommended for prevention of chronic disease, and is thought to reduce raised liver fat, yet there have been few randomized controlled trials with accurate measurement of liver fat. We assessed the effect of 12 weeks of supplementation with omega-3 PUFA from fish oil versus placebo on quantified liver fat, liver tests, and body composition including visceral adipose tissue (VAT) in a double-blind randomized controlled trial. Fifty apparently healthy overweight men (BMI 25.0–29.9 kg/m²; waist > 94 cm) were randomly allocated to consume fish oil (total daily dose: 1728 mg marine triglycerides, of which 588 mg EPA and 412 mg DHA, combined with 200 mg antioxidant, coenzyme Q10) or placebo (olive oil capsules) daily for 12 weeks. Liver fat was assessed using proton magnetic resonance spectroscopy. All outcomes were assessed at baseline and following 6 and 12 weeks of supplementation. Baseline liver fat was 4.6 ± 0.5% (range: 0.6 to 18.2%); 16 (32%) participants met the criteria for NAFLD (>5.5% liver fat). Repeated measures ANOVA revealed no significant time or group × time effect for fish oil versus placebo for liver fat, liver enzymes, anthropometry, or body composition including VAT (p > 0.05 for all), with similar finding for sub-analysis of participants with NAFLD. Omega-3 PUFA did not appear to be an effective agent for reducing liver fat in overweight men. The factors determining the health benefits of omega-3 PUFA supplementation on an individual level need to be clarified.

Mechanisms Preserving Insulin Action during High Dietary Fat Intake

Prolonged intervention studies investigating molecular metabolism are necessary for a deeper understanding of dietary effects on health. Here we provide mechanistic information about metabolic adaptation to fat-rich diets. Healthy, slightly overweight men ingested saturated or polyunsaturated fat-rich diets for 6 weeks during weight maintenance. Hyperinsulinemic clamps combined with leg balance technique revealed unchanged peripheral insulin sensitivity, independent of fatty acid type. Both diets increased fat oxidation potential in muscle. Hepatic insulin clearance increased, while glucose production, de novo lipogenesis, and plasma triacylglycerol decreased. High fat intake changed the plasma proteome in the immune-supporting direction and the gut microbiome displayed changes at taxonomical and functional level with polyunsaturated fatty acid (PUFA). In mice, eucaloric feeding of human PUFA and saturated fatty acid diets lowered hepatic triacylglycerol content compared with low-fat-fed control mice, and induced adaptations in the liver supportive of decreased gluconeogenesis and lipogenesis. Intake of fat-rich diets thus induces extensive metabolic adaptations enabling disposition of dietary fat without metabolic complications.

Diet with greater inflammatory potential is associated with higher prevalence of fatty liver among US adults

The prevalence of non-alcoholic fatty liver disease (NAFLD) is rising-caused, at least in part, by unhealthy lifestyles including poor dietary choices. We examined the link between the inflammatory potential of diet as measured by the Dietary Inflammatory Index (DII^®) and liver function tests [summarised by the fatty liver index (FLI)]. Of 20,643 US NHANES participants, 48.7% were men and the mean age was 47.3 years. Significant associations were apparent between increasing DII score and prevalent fatty liver. Individuals in the fourth DII quartile had nearly a six-fold higher likelihood of fatty liver [odds ratio (OR) = 5.97, 95% confidence interval: 4.44-8.02] compared with those in the first quartile. Moderation analysis indicated a significant impact of adiposity on the link between FLI and DII score (p < 0.001). This study provides further evidence of an association between the inflammatory potential of diet and fatty liver.

Microbiota, Obesity and NAFLD

Non-alcoholic fatty liver disease (NAFLD) is an increasingly important cause of chronic liver disease globally. Similar to metabolic syndrome and obesity, NAFLD is associated with alternations in the gut microbiota and its related biological pathways. While the exact pathophysiology of NAFLD remains largely unknown, changes in intestinal inflammation, gut permeability, energy harvest, anaerobic fermentation and insulin resistance have been described. In this chapter, we review the relationship between the gut microbiota, obesity and NAFLD, and highlight potential ways to modify the gut microbiota to help managing NAFLD patients.

In a pilot study, reduced fatty acid desaturase 1 function was associated with nonalcoholic fatty liver disease and response to treatment in children

BACKGROUND

FADS1 gene encodes delta 5 desaturase, a rate-limiting enzyme in the metabolism of n-3 and n-6 polyunsaturated fatty acids (PUFAs). Minor alleles of FADS1 locus polymorphisms are associated with reduced FADS1 expression and intra-hepatic fat accumulation. However, the relationship between FADS1 expression and pediatric nonalcoholic fatty liver disease (NAFLD) risk remains to be explored.

METHODS

We analyzed FADS1 transcription levels and their association with intra-hepatic fat and histology in children, and we performed pathway enrichment analysis on transcriptomic profiles associated with FADS1 polymorphisms. We also evaluated the weight of FADS1 alleles on the response to combined docosahexaenoic acid, choline, and vitamin E (DHA-CHO-VE) treatment.

RESULTS

FADS1 mRNA level was significantly and inversely associated with intra-hepatic fat (p = 0.004), degree of steatosis (p = 0.03), fibrosis (p = 0.05), and NASH (p = 0.008) among pediatric livers. Transcriptomics demonstrated a significant enrichment of a number of pathways strongly related to NAFLD (e.g., liver damage, fibrosis, and hepatic stellate cell activation). Compared to children who are common allele homozygotes, children with FADS1 minor alleles had a greater reduction in steatosis, fibrosis, and NAFLD activity score after DHA-CHO-VE.

CONCLUSION

This study suggests that decreased FADS1 expression may be associated with NAFLD in children but an increased response to DHA-CHO-VE.