Patients with Nonalcoholic Fatty Liver Disease Have a Low Response Rate to Vitamin D Supplementation

Vitamin D and Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD): Novel Mechanistic Insights

Metabolic dysfunction-associated steatotic liver disease (MASLD) is an increasingly prevalent condition characterized by abnormal fat accumulation in the liver, often associated with metabolic disorders. Emerging evidence suggests a potential link between vitamin D deficiency and the development and progression of MASLD. The current review provides a concise overview of recent studies uncovering novel mechanistic insights into the interplay between vitamin D and MASLD. Several epidemiological studies have highlighted a significant association between low vitamin D levels and an increased risk of MASLD. Vitamin D, traditionally known for its role in bone health, has now been recognized as a key player in various physiological processes, including immune regulation and inflammation. Experimental studies using animal models have demonstrated that vitamin D deficiency exacerbates liver steatosis and inflammation, suggesting a potential protective role against MASLD. Mechanistically, vitamin D appears to modulate MASLD through multiple pathways. Firstly, the vitamin D receptor (VDR) is abundantly expressed in liver cells, indicating a direct regulatory role in hepatic function. Activation of the VDR has been shown to suppress hepatic lipid accumulation and inflammation, providing a mechanistic basis for the observed protective effects. Additionally, vitamin D influences insulin sensitivity, a critical factor in MASLD pathogenesis. Improved insulin sensitivity may mitigate the excessive accumulation of fat in the liver, thus attenuating MASLD progression. In parallel, vitamin D exhibits anti-inflammatory properties by inhibiting pro-inflammatory cytokines implicated in MASLD pathophysiology. Experimental evidence suggests that the immunomodulatory effects of vitamin D extend to the liver, reducing inflammation and oxidative stress, key drivers of MASLD, and the likelihood of hepatocyte injury and fibrosis. Understanding the complex interplay between vitamin D and MASLD provides a basis for exploring targeted therapeutic strategies and preventive interventions. As vitamin D deficiency is a modifiable risk factor, addressing this nutritional concern may prove beneficial in mitigating the burden of MASLD and associated metabolic disorders.

Effects of vitamin D supplementation on liver fibrogenic factors, vitamin D receptor and liver fibrogenic microRNAs in metabolic dysfunction-associated steatotic liver disease (MASLD) patients: an exploratory randomized clinical trial

BACKGROUND AND AIMS

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a global metabolic problem which can lead to irreversible liver fibrosis. It has been shown that vitamin D and its receptors contribute to fibrogenic pathways in the liver. However, the effect of vitamin D supplementation on liver fibrosis related factors have not been examined. This double blinded placebo controlled clinical trial was designed to investigate the effects on vitamin D supplementation on serum levels of VDR, fibrogenic factors and fibrogenic MicroRNAs in MASLD patients.

METHODS

Forty six MASLD patients after block matching for sex and BMI were randomly assigned to receive 4000 IU/d vitamin D or placebo for 12 weeks. Weight, height and waist circumference were measured. Serum fibrogenic microRNAs, laminin, collagen type IV, hyaluronic acid, vitamin D, VDR, PTH, blood fasting glucose, serum fasting insulin, lipid profile, ALT and AST were determined at the baseline and at the end of the trial. Insulin resistance and insulin sensitivity were calculated using the HOMA-IR and QUICKI equation.

RESULTS

Supplementation with vitamin D for 12 weeks led to the significant increases in serum 25(OH) vitamin D, VDR and HDL-C compared to placebo (P < 0.001, P = 0.008 and P < 0.001). There were significant decreases in ALT, AST, FBS and LDL-C levels in the vitamin D group as compared to the placebo (P < 0.05). Laminin and hyaluronic acid concentrations were significantly decreased in the vitamin D group as compared to the placebo group, by -10.6 and - 28.7 ng/mL, respectively. Supplementation with vitamin D for 12 weeks resulted in a significant lower MiR-21 and MiR-122 gene expressions compared to the placebo group (P = 0.01 and P < 0.001, respectively).

DISCUSSION

As the first randomized controlled trial on the effect of vitamin D supplementation on serum levels of VDR, fibrogenic factors and fibrogenic MicroRNAs in MASLD patients, we found a significant reduction in some liver fibrogenic factors, in liver transaminases and corresponding changes in some fibrosis-related MiRs and some metabolic factors. Further clinical trials with larger sample sizes and direct measures of liver fibrosis are needed to confirm these findings.

TRIAL REGISTRATION NUMBER

(available at: http://www.irct.ir , identifier: IRCT201405251485N13), Registration date: 14-03-2017.

What Does Sarcopenia Have to Do with Nonalcoholic Fatty Liver Disease?

Nonalcoholic fatty liver disease (NAFLD) is one of the most common causes of chronic liver disease. As the second stage of developing steatosis, nonalcoholic hepatitis (NASH) carries the risk of fibrosis, cirrhosis, and hepatocellular carcinoma. Sarcopenia is defined as a condition characterized by a decrease in muscle mass and functional decline. Both NAFLD and sarcopenia are global problems. The pathophysiological mechanisms that link the two entities of the disease are insulin resistance, inflammation, nutritional deficiencies, impairment of myostatin and adiponectin, or physical inactivity. Furthermore, disorders of the gut-liver axis appear to induce the process of developing NAFLD and sarcopenia. The correlations between NAFLD and sarcopenia appear to be bidirectional, so the main objective of the review was to determine the cause-and-effect relationship between the two diseases.

Vitamin D/vitamin D receptor pathway in non-alcoholic fatty liver disease

INTRODUCTION

Non-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease worldwide, but underlying mechanisms are not fully understood. In recent years, a growing body of evidence has emphasized the therapeutic role of vitamin D in NAFLD, but the specific mechanism remains to be investigated.

AREAS COVERED

This review summarized the roles of vitamin D/VDR (vitamin D receptor) pathway in different types of liver cells (such as hepatocytes, hepatic stellate cells, liver macrophages, T lymphocytes, and other hepatic immune cells) in case of NAFLD. Meanwhile, the effects of pathways in the gut-liver axis, adipose tissue-liver axis, and skeletal muscle-liver axis on the development of NAFLD were further reviewed. Relevant literature was searched on PubMed for the writing of this review.

EXPERT OPINION

The precise regulation of regional vitamin D/VDR signaling pathway based on cell-specific or tissue-specific function will help clarify the potential mechanism of vitamin D in NAFLD, which may provide new therapeutic targets to improve the safety and efficacy of vitamin D based drugs.

Indices of hepatic steatosis and fibrosis in prediabetes and association with diabetes development in the vitamin D and type 2 diabetes study

AIMS

Non-alcoholic fatty liver disease (NAFLD) is a common comorbidity that leads to poor outcomes in people at high risk for development of type 2 diabetes (T2D). Vitamin D is a possible mediator. In the vitamin D and type 2 diabetes study (D2d), we investigated the relationship of baseline indices of NAFLD with incident T2D and whether the effect of vitamin D on diabetes was modified by NAFLD.

METHODS

Cross-sectional associations of indices of NAFLD with glycemia and vitamin D status were assessed in 3972 individuals screened for the D2d study. In those with prediabetes randomized to vitamin D or placebo (n = 2423), we examined longitudinal associations of NAFLD indices with incident T2D. We used validated non-invasive scores to assess steatosis [(hepatic steatosis index (HSI); NAFLD-liver fat score (NAFLD-LFS)] and advanced fibrosis [fibrosis-4 (FIB-4) index; AST to Platelet Ratio Index (APRI)].

RESULTS

Eighty-five percent of screened participants had likely steatosis by HSI and 71 % by NAFLD-LFS; 3 % were likely to have advanced fibrosis by FIB-4 and 1.2 % by APRI. FIB-4 indicated that 20.4 % of individuals require further follow up to assess liver health. Steatosis and fibrosis scores were higher among participants with worse glycemia. The NAFLD-LFS and APRI predicted development of diabetes (hazard ratios [95%CI] 1.35 [1.07, 1.70]; P = 0.012) and 2.36 (1.23, 4.54; P = 0.010), respectively). The effect of vitamin D on diabetes risk was not modified by baseline NAFLD indices. Individuals with likely steatosis had a smaller increase in serum 25-hydroxyvitamin D level in response to vitamin D than those without steatosis.

CONCLUSIONS

The predicted high prevalence of steatosis, the need for further fibrosis workup, and the relationship between liver health and incident T2D suggest that routine screening with clinically accessible scores may be an important strategy to reduce disease burden.

Beneficial Effect of Vitamin D on Non-Alcoholic Fatty Liver Disease (NAFLD) Progression in the Zebrafish Model

A major cause of chronic liver disease, cirrhosis, and hepatocellular carcinoma, non-alcoholic fatty liver disease (NAFLD) results from excessive liver fat accumulation. Vitamin D (VitD) plays multiple important roles in diverse physiologic processes. Here, we describe the role of VitD in the complex pathogenesis of NAFLD and explore the possible therapeutic role of VitD supplementation in NAFLD therapy. To compare the effect of VitD to other interventions such as low-calorie diet, we induced NAFLD in young adult zebrafish (Danio rerio, AB strain) and monitored the effects of VitD supplementation on the disease course. The zebrafish administered with high-dose VitD (1.25 μg) had significantly reduced liver fat compared to those that received low-dose VitD (0.049 μg) or caloric restriction. Gene expression analysis revealed that VitD downregulated several pathways that may play a role in NAFLD etiology, which affected fatty acid metabolism, vitamins and their cofactors, ethanol oxidation, and glycolysis. The pathway analysis revealed that the cholesterol biosynthesis pathway and the isoprenoid biosynthetic process pathway were significantly upregulated whereas the small molecule catabolic process pathway significantly downregulated following the exposure of NAFLD zebrafish model to high VitD dose. Therefore, our findings suggest the association of novel biochemical pathways with NAFLD and highlight the potential of VitD supplementation to reverse the severity of NAFLD, especially in younger people.

Nutrition and Chronic Liver Disease

Malnutrition is common in chronic liver diseases and worsens the patient’s prognosis. Many liver disorders are associated with nutritional deficiencies. Some of the main factors that can lead to malnutrition in patients with chronic liver disease include decreased lipid absorption and reduced albumin production. In addition, these patients are sometimes candidates for a liver transplant that requires nutritional intervention after surgery to improve their prognosis. Thus, it is very important to recognise malnutrition in patients with liver failure in order to resolve it, mainly by a complete history of the patient, dietary survey, determination of muscle mass and a subjective assessment. To ensure a good nutritional status, exercise and lifestyle changes are considered, including dietary modifications, especially with a Mediterranean pattern. This article reviews these topics, including dietary modifications before and after liver transplantation. Additionally, nutritional recommendations are offered to patients with metabolic hepatic steatosis.

Non-alcoholic Fatty Liver Disease and Steatohepatitis: Risk Factors and Pathophysiology

Non-alcoholic fatty liver disease (NAFLD) and its progressive subtype non-alcoholic steatohepatitis (NASH) are the most prevalent liver diseases, often leading to hepatocellular carcinoma (HCC). This review aims to describe the present knowledge of the risk factors responsible for the development of NAFLD and NASH. I performed a literature review identifying studies focusing on the complex pathogenic pathway and risk factors of NAFLD and steatohepatitis. The relationship between NAFLD and metabolic syndrome is well established and widely recognized. Obesity, dyslipidemia, type 2 diabetes, hypertension, and insulin resistance are the most common risk factors associated with NAFLD. Among the components of metabolic syndrome, current evidence strongly suggests obesity and type 2 diabetes as risk factors of NASH and HCC. However, other elements, namely gender divergences, ethnicity, genetic factors, participation of innate immune system, oxidative stress, apoptotic pathways, and adipocytokines, take a leading role in the onset and promotion of NAFLD. Pathophysiological mechanisms that are responsible for NAFLD development and subsequent progression to NASH are insulin resistance and hyperinsulinemia, oxidative stress, hepatic stellate cell (HSC) activation, cytokine/adipokine signaling pathways, and genetic and environmental factors. Major pathophysiological findings of NAFLD are dysfunction of adipose tissue through the enhanced flow of free fatty acids (FFAs) and release of adipokines, and altered gut microbiome that generate proinflammatory signals and cause NASH progression. Understanding the pathophysiology and risk factors of NAFLD and NASH; this review could provide insight into the development of therapeutic strategies and useful diagnostic tools.

Vitamin D3 enhances the effects of omega-3 oils against metabolic dysfunction-associated fatty liver disease in rat

This study investigated the effects of omega-3 oils (OM) and/or vitamin D₃ (VD) against metabolic dysfunction-associated fatty liver disease (MAFLD). Forty rats were divided into negative (NC) and positive (PC) controls, OM, VD, and OM + VD groups, and MAFLD was induced by high-fat/high-fructose diet (12 weeks). Oral OM (415 mg/kg/day) and/or intramuscular VD (290 IU/kg/day) were given for 4 weeks (5 times/week). The PC animals were markedly obese and had hyperglycemia, insulin resistance, dyslipidemia, elevated liver enzymes, abnormal hepatic histology, and increased caspase-3 with apoptosis than the NC group. The expression of hepatic peroxisome proliferator-activated receptor-α (PPAR-α; 5.3-fold), insulin induced gene-1 (INSIG1; 7.8-fold), adiponectin receptor-1 (AdipoR1; 4.4-fold), and leptin receptor (LEPR; 6-fold) declined, while PPAR-γ (3.7-fold) and sterol regulatory element-binding protein-1 (SREBP1; 2.4-fold) increased, in the PC than the NC group. Leptin (2.2-fold), malondialdehyde (2.1-fold), protein carbonyl groups (17.3-fold), IL-1β (4.4-fold), IL-6 (2.1-fold), TNF-α (1.8-fold) also increased, whereas adiponectin (2.8-fold) glutathione (2.1-fold), glutathione peroxidase-1 (2.4-fold), glutathione reductase (2.2-fold), catalase (1.4-fold), and IL-10 (2.8-fold) decreased, in the PC livers. Both monotherapies attenuated obesity, metabolic profiles, and PPAR-γ/SREBP1/leptin/Caspase-3/apoptosis, while induced PPAR-α/adiponectin/AdipoR1/LEPR/INSIG1. The monotherapies also reduced the oxidative stress and pro-inflammatory markers and increased the antioxidant and anti-inflammatory molecules. However, the OM effects were better than VD monotherapy. Alternatively, the co-therapy group showed the greatest ameliorations in liver functions, lipid-regulatory molecules, oxidative stress, inflammation, and apoptosis. In conclusion, while OM monotherapy was superior to VD, the co-therapy protocol displayed the best alleviations against MAFLD, possibly by enhanced modulation of metabolic, antioxidant, and anti-inflammatory pathways.

Vitamin D supplementation for chronic liver diseases in adults

BACKGROUND

Vitamin D deficiency is often reported in people with chronic liver diseases. Improving vitamin D status could therefore be beneficial for people with chronic liver diseases.

OBJECTIVES

To assess the beneficial and harmful effects of vitamin D supplementation in adults with chronic liver diseases.

SEARCH METHODS

We searched the Cochrane Hepato-Biliary Group Controlled Trials Register, CENTRAL, MEDLINE Ovid, Embase Ovid, LILACS, Science Citation Index Expanded, and Conference Proceedings Citation Index-Science. We also searched ClinicalTrials.gov  and the World Health Organization International Clinical Trials Registry Platform. We scanned bibliographies of relevant publications and enquired experts and pharmaceutical companies as to additional trials. All searches were up to November 2020.

SELECTION CRITERIA

Randomised clinical trials that compared vitamin D at any dose, duration, and route of administration versus placebo or no intervention in adults with chronic liver diseases. Vitamin D could have been administered as supplemental vitamin D (vitamin D₃ (cholecalciferol) or vitamin D₂ (ergocalciferol)), or an active form of vitamin D (1α-hydroxyvitamin D (alfacalcidol), 25-hydroxyvitamin D (calcidiol), or 1,25-dihydroxyvitamin D (calcitriol)).

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. We used GRADE to assess the certainty of evidence.

MAIN RESULTS

We included 27 randomised clinical trials with 1979 adult participants. This review update added 12 trials with 945 participants. We assessed all trials as at high risk of bias. All trials had a parallel-group design. Eleven trials were conducted in high-income countries and 16 trials in middle-income countries. Ten trials included participants with chronic hepatitis C, five trials participants with liver cirrhosis, 11 trials participants with non-alcoholic fatty liver disease, and one trial liver transplant recipients. All of the included trials reported the baseline vitamin D status of participants. Participants in nine trials had baseline serum 25-hydroxyvitamin D levels at or above vitamin D adequacy (20 ng/mL), whilst participants in the remaining 18 trials were vitamin D insufficient (less than 20 ng/mL). Twenty-four trials administered vitamin D orally, two trials intramuscularly, and one trial intramuscularly and orally. In all 27 trials, the mean duration of vitamin D supplementation was 6 months, and the mean follow-up of participants from randomisation was 7 months. Twenty trials (1592 participants; 44% women; mean age 48 years) tested vitamin D₃ (cholecalciferol); three trials (156 participants; 28% women; mean age 54 years) tested vitamin D₂; four trials (291 participants; 60% women; mean age 52 years) tested 1,25-dihydroxyvitamin D; and one trial (18 participants; 0% women; mean age 52 years) tested 25-hydroxyvitamin D. One trial did not report the form of vitamin D. Twelve trials used a placebo, whilst the other 15 trials used no intervention in the control group. Fourteen trials appeared to be free of vested interest. Eleven trials did not provide any information on clinical trial support or sponsorship. Two trials were funded by industry. We are very uncertain regarding the effect of vitamin D versus placebo or no intervention on all-cause mortality (risk ratio (RR) 0.86, 95% confidence interval (CI) 0.51 to 1.45; 27 trials; 1979 participants). The mean follow-up was 7 months (range 1 to 18 months). We are very uncertain regarding the effect of vitamin D versus placebo or no intervention on liver-related mortality (RR 1.62, 95% CI 0.08 to 34.66; 1 trial; 18 participants) (follow-up: 12 months); serious adverse events such as hypercalcaemia (RR 5.00, 95% CI 0.25 to 100.8; 1 trial; 76 participants); myocardial infarction (RR 0.75, 95% CI 0.08 to 6.81; 2 trials; 86 participants); thyroiditis (RR 0.33, 95% CI 0.01 to 7.91; 1 trial; 68 participants); circular haemorrhoidal prolapse (RR 3.00, 95% CI 0.14 to 65.9; 1 trial; 20 participants); bronchopneumonia (RR 0.33, 95% CI 0.02 to 7.32; 1 trial 20 participants); and non-serious adverse events. The certainty of evidence for all outcomes is very low. We found no data on liver-related morbidity such as gastrointestinal bleeding, hepatic encephalopathy, hepatorenal syndrome, ascites, or liver cancer. There were also no data on health-related quality of life. The evidence is also very uncertain regarding the effect of vitamin D versus placebo or no intervention on rapid, early, and sustained virological response in people with chronic hepatitis C.

AUTHORS' CONCLUSIONS

Given the high risk of bias and insufficient power of the included trials and the very low certainty of the available evidence, vitamin D supplementation versus placebo or no intervention may increase or reduce all-cause mortality, liver-related mortality, serious adverse events, or non-serious adverse events in adults with chronic liver diseases. There is a lack of data on liver-related morbidity and health-related quality of life. Further evidence on clinically important outcomes analysed in this review is needed.

Non-alcoholic fatty liver and chronic kidney disease: Retrospect, introspect, and prospect

With the growing prevalence of obesity and diabetes in the United States and across the world, a rise in the overall incidence and prevalence of non-alcoholic fatty liver disease (NAFLD) is expected. The risk factors for NAFLD are also associated with the development of chronic kidney disease (CKD). We review the epidemiology, risk factors, genetics, implications of gut dysbiosis, and specific pathogenic mechanisms linking NAFLD to CKD. Mechanisms such as ectopic lipid accumulation, cellular signaling abnormalities, and the interplay between fructose consumption and uric acid accumulation have led to the emergence of potential therapeutic implications for this patient population. Transplant evaluation in the setting of both NAFLD and CKD is also reviewed. Potential strategies for surveillance and management include the monitoring of comorbidities, the use of non-invasive fibrosis scoring systems, and the measurement of laboratory markers. Lastly, we discuss the management of patients with NAFLD and CKD, from preventative measures to experimental interventions.

Is vitamin D receptor a druggable target for non-alcoholic steatohepatitis?

Nonalcoholic steatohepatitis (NASH) is a progressed stage of non-alcoholic fatty liver disease, and available therapeutic strategies for NASH are limited. Vitamin D receptor (VDR) is proposed as a druggable target for NASH due to the discovery of vitamin D deficiency in NASH patients. To date, vitamin D supplementation has not consistently conferred expected therapeutic benefits, raising the question of whether VDR can serve as a proper drug target for NASH. It is known that VDR can interact with other ligands such as bile acids in addition to vitamin D, and its expression can be induced by fatty acids, and insulin. It has also been shown that while activation of VDR in hepatic macrophages and hepatic stellate cells resulted in attenuation of hepatic inflammation and fibrosis, activation of VDR in hepatocytes could accelerate lipid accumulation. Thus, the multiplicity of VDR ligands, together with the cell type-specificity of VDR activation, must be taken into consideration in assessing the validity of VDR being a potential druggable target for NASH treatment. To this end, we have evaluated the relationship between VDR activation and various contributing factors, such as gut microbiota, bile acid, fatty acids, and insulin, in addition to vitamin D, with an expectation that a potential drug might be identified that can elicit VDR activation in a tissue- and/or cell type-specific manner and therefore achieving therapeutic benefits in NASH.

Association of serum vitamin D level and nonalcoholic fatty liver disease: a meta-analysis

We aimed to explore the potential link of serum vitamin D level with nonalcoholic fatty liver disease (NAFLD). PubMed, Embase and the Cochrane Library database were searched until the end of February 2018. Clinical studies with sufficient data investigating the relationship between serum vitamin D and NAFLD were included. The outcome data were processed to make an overall estimate of combined standardized mean differences (SMD) and pooled odds ratio (OR)/hazard ratios with 95% confidence intervals (CIs). Of the 309 initially retrieved studies, 15 studies of high quality involving a total of 20 096 participants (including 7803 NAFLD patients) were included in this meta-analysis. Meta-analysis of continuous data indicated that NAFLD patients had averagely 0.90 ng/ml lower levels of 25-hydroxyvitamin D compared with the non-NAFLD subjects (SMD -0.90; 95% CI: -1.29 to -0.52). Parallelly, pooled dichotomous data revealed that serum vitamin D level is negatively associated with NAFLD (OR = 0.64, 95% CI = 0.54-0.77), albeit with substantial heterogeneity. Next, subgroup analysis showed that Western NAFLD patients were more likely to be vitamin D deficient (OR = 0.60, 95% CI = 0.46-0.78). Finally, meta-regression showed that sample size, ethnic background, and diagnosis of NAFLD were possible sources of heterogeneity in the meta-analysis. Our results revealed that serum vitamin D level was inversely associated with an increased risk of NAFLD. Patients with hypovitaminosis D might benefit from extra supplement of vitamin D against the risk of NAFLD.

Vitamin D deficiency: prevalence and association with liver disease severity in pediatric nonalcoholic fatty liver disease

BACKGROUND/OBJECTIVES

To determine associations between serum 25-hydroxyvitamin D (25(OH)-D) concentrations and histologic nonalcoholic fatty liver disease (NAFLD) severity.

SUBJECTS/METHODS

Clinical, laboratory, and histology data were collected retrospectively in a pediatric cohort with biopsy-confirmed NAFLD. Serum 25(OH)-D concentrations were used to define vitamin D deficiency (≤20 ng/ml), insufficiency (21-30 ng/ml), and sufficiency (≥31 ng/ml).

RESULTS

In all, 234 patients (78% non-Hispanic, median age 14 years) were included. The majority (n = 193) were either vitamin D insufficient (50%) or deficient (32%). Eighty-four patients (36%) reported taking vitamin D supplements at the time of biopsy; serum 25(OH)-D concentrations were not higher in those supplemented. There were no differences in the demographic, clinical, and laboratory characteristics of the three vitamin D status groups. Severity of steatosis, ballooning, lobular/portal inflammation, and NAFLD activity score were also not different between the groups. The proportion of patients with significant fibrosis (stage ≥ 2) was higher in those with insufficiency (29%) compared to those who were sufficient (17%) or deficient (15%, p = 0.04). After controlling for important covariates selected from age, body mass index, ethnicity, vitamin D supplementation, and season, the insufficient group had increased odds of a higher fibrosis score compared to the sufficient group (adjusted OR, 2.04; 95%CI, 1.02-4.08).

CONCLUSIONS

Vitamin D deficiency and insufficiency are common in children with NAFLD, but not consistently related with histologic disease severity. Prospective longitudinal studies are needed to determine optimal dosing strategies to achieve sufficiency and to determine whether adequate supplementation has an impact on histology.

Emerging awareness on the importance of skeletal muscle in liver diseases: time to dig deeper into mechanisms!

Skeletal muscle is a tissue that represents 30–40% of total body mass in healthy humans and contains up to 75% of total body proteins. It is thus the largest organ in non-obese subjects. The past few years have seen increasing awareness of the prognostic value of appreciating changes in skeletal muscle compartment in various chronic diseases. Hence, a low muscle mass, a low muscle function and muscle fatty infiltration are linked with poor outcomes in many pathological conditions. In particular, an affluent body of evidence links the severity, the complications and mortality of chronic liver disease (CLD) with skeletal muscle depletion. Yet it is still not clear whether low muscle mass is a cause, an aggravating factor, a consequence of the ongoing disease, or an epiphenomenon reflecting general alteration in the critically ill patient. The mechanisms by which the muscle compartment influences disease prognosis are still largely unknown. In addition, whether muscle alterations contribute to liver disease progression is an unanswered question. Here, we first review basic knowledge about muscle compartment to draw a conceptual framework for interpreting skeletal muscle alteration in CLD. We next describe recent literature on muscle wasting in cirrhosis and liver transplantation. We then discuss the implication of skeletal muscle compartment in non-alcoholic fatty liver disease (NAFLD)/non-alcoholic steatohepatitis (NASH), focusing on plausible metabolic disruption in muscle compartment that might participate in NAFLD progression. Finally, we discuss shortcomings and challenges we need to address in the near future prior to designate the muscle compartment as a therapeutic target in CLD.

A Randomized, Controlled Trial of Vitamin D Supplementation on Cardiovascular Risk Factors, Hormones, and Liver Markers in Women with Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) increases the risk of metabolic syndrome and non-alcoholic-fatty-liver disease (NAFLD). Vitamin D supplementation may exert positive effects on liver biochemistry in patients with NAFLD; however, its effects on PCOS are unknown. This randomized, double-blind, placebo-controlled study explored the effect of vitamin D supplementation on cardiovascular risk factors (high-sensitivity C-reactive protein (hs-CRP), weight, body mass index (BMI), lipid profile, glucose levels, insulin levels, the homeostatic model assessment-insulin resistance (HOMA-IR), hormones (free androgen index (FAI), testosterone, sex hormone binding globulin (SHBG), and liver markers (alanine aminotransferase (ALT), hyaluronic acid (HA), N-terminal pro-peptide of type III procollagen (PIIINP), tissue inhibitor of metallo-proteinases-1 (TIMP-1), and the enhanced liver fibrosis (ELF) score). Forty women with PCOS were recruited and randomized to vitamin D (3200 IU) or placebo daily for 3 months. All outcomes were measured at baseline and 3 months follow-up (FU). Greater increases in vitamin D levels were shown in the supplementation group (vitamin D, baseline: 25.6 ± 11.4 nmol/L, FU: 90.4 ± 19.5 nmol/L vs. placebo, baseline: 30.9 ± 11.1 nmol/L, FU: 47.6 ± 20.5 nmol/L, p < 0.001). Between groups comparisons (% baseline change) revealed significant differences in ALT (p = 0.042) and a weak effect indicating a greater reduction in the HOMA-IR in the vitamin D group (p = 0.051). No further between group differences were seen in other cardiovascular risk factor, liver markers, or hormones. This study supports beneficial effects of vitamin D supplementation on liver markers and modest improvements in insulin sensitivity in vitamin D deficient women with PCOS.

EASL Clinical Practice Guidelines on nutrition in chronic liver disease

A frequent complication in liver cirrhosis is malnutrition, which is associated with the progression of liver failure, and with a higher rate of complications including infections, hepatic encephalopathy and ascites. In recent years, the rising prevalence of obesity has led to an increase in the number of cirrhosis cases related to non-alcoholic steatohepatitis. Malnutrition, obesity and sarcopenic obesity may worsen the prognosis of patients with liver cirrhosis and lower their survival. Nutritional monitoring and intervention is therefore crucial in chronic liver disease. These Clinical Practice Guidelines review the present knowledge in the field of nutrition in chronic liver disease and promote further research on this topic. Screening, assessment and principles of nutritional management are examined, with recommendations provided in specific settings such as hepatic encephalopathy, cirrhotic patients with bone disease, patients undergoing liver surgery or transplantation and critically ill cirrhotic patients.

Tissue-specific pathways and networks underlying sexual dimorphism in non-alcoholic fatty liver disease

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) encompasses benign steatosis and more severe conditions such as non-alcoholic steatohepatitis (NASH), cirrhosis, and liver cancer. This chronic liver disease has a poorly understood etiology and demonstrates sexual dimorphisms. We aim to examine the molecular mechanisms underlying sexual dimorphisms in NAFLD pathogenesis through a comprehensive multi-omics study. We integrated genomics (DNA variations), transcriptomics of liver and adipose tissue, and phenotypic data of NAFLD derived from female mice of ~ 100 strains included in the hybrid mouse diversity panel (HMDP) and compared the NAFLD molecular pathways and gene networks between sexes.

RESULTS

We identified both shared and sex-specific biological processes for NAFLD. Adaptive immunity, branched chain amino acid metabolism, oxidative phosphorylation, and cell cycle/apoptosis were shared between sexes. Among the sex-specific pathways were vitamins and cofactors metabolism and ion channel transport for females, and phospholipid, lysophospholipid, and phosphatidylinositol metabolism and insulin signaling for males. Additionally, numerous lipid and insulin-related pathways and inflammatory processes in the adipose and liver tissue appeared to show more prominent association with NAFLD in male HMDP. Using data-driven network modeling, we identified plausible sex-specific and tissue-specific regulatory genes as well as those that are shared between sexes. These key regulators orchestrate the NAFLD pathways in a sex- and tissue-specific manner. Gonadectomy experiments support that sex hormones may partially underlie the sexually dimorphic genes and pathways involved in NAFLD.

CONCLUSIONS

Our multi-omics integrative study reveals sex- and tissue-specific genes, processes, and networks underlying sexual dimorphism in NAFLD and may facilitate sex-specific precision medicine.

Blunted serum 25(OH)D response to vitamin D3 supplementation in children with autism

Introduction: Data suggest a potential role for vitamin D in autism spectrum disorder (ASD) prevention and treatment. It is likely that the serum response to vitamin D supplementation contributes to its effectiveness. Multiple factors affect serum vitamin D 25(OH)D response to supplementation. Methods: We conducted post-hoc analysis of two double-blind, randomized, placebo-controlled trials (RCT) of vitamin D₃ supplementation, one RCT involving children with ASD and another involving children with asthma. Both trials were conducted in the same geographic location (Dublin, Ireland, 53°N), conducted over Winter season and utilized the same vitamin D₃ dose (2000 IU/day). Results: We included 18 children with ASD and 17 children with asthma. There was no significant difference in 25(OH)D or age at baseline, however, BMI was significantly lower in ASD (P = 0.03). Compliance with vitamin D supplementation was high in both trials. Despite a significantly longer intervention period (20w vs. 15w; P < 0.0001), ASD children had a significantly lower absolute increase (+26 vs. +45 nmol/l) in 25(OH)D (P = 0.04). Conclusions: Despite similar demographics, children with ASD had a lower increase in 25(OH)D levels with supplementation. Potential mechanisms include altered absorption/metabolism as well as well genetic factors. Clinical and research work relating to vitamin D is ASD should measure 25(OHO)D response to supplementation to assess therapeutic doses.

Micronutrients in Nonalcoholic Fatty Liver Disease Pathogenesis

Micronutrients include electrolytes, minerals, vitamins, and carotenoids, and are required in microgram or milligram quantities for cellular metabolism. The liver plays an important role in micronutrient metabolism and this metabolism often is altered in chronic liver diseases. Here, we review how the liver contributes to micronutrient metabolism; how impaired micronutrient metabolism may be involved in the pathogenesis of nonalcoholic fatty liver disease (NAFLD), a systemic disorder of energy, glucose, and lipid homeostasis; and how insights gained from micronutrient biology have informed NAFLD therapeutics. Finally, we highlight some of the challenges and opportunities that remain with investigating the contribution of micronutrients to NAFLD pathology and suggest strategies to incorporate our understanding into the care of NAFLD patients.

Nutritional issues in patients with obesity and cirrhosis

Obesity and metabolic syndrome are considered as responsible for a condition known as the non-alcoholic fatty liver disease that goes from simple accumulation of triglycerides to hepatic inflammation and may progress to cirrhosis. Patients with obesity also have an increased risk of primary liver malignancies and increased body mass index is a predictor of decompensation of liver cirrhosis. Sarcopenic obesity confers a risk of physical impairment and disability that is significantly higher than the risk induced by each of the two conditions alone as it has been shown to be an independent risk factor for chronic liver disease in patients with obesity and a prognostic negative marker for the evolution of liver cirrhosis and the results of liver transplantation. Cirrhotic patients with obesity are at high risk for depletion of various fat-soluble, water-soluble vitamins and trace elements and should be supplemented appropriately. Diet, physical activity and protein intake should be carefully monitored in these fragile patients according to recent recommendations. Bariatric surgery is sporadically used in patients with morbid obesity and cirrhosis also in the setting of liver transplantation. The risk of sarcopenia, micronutrient status, and the recommended supplementation in patients with obesity and cirrhosis are discussed in this review. Furthermore, the indications and contraindications of bariatric surgery-induced weight loss in the cirrhotic patient with obesity are discussed.

Effect of vitamin D supplementation on fasting plasma glucose, insulin resistance and prevention of type 2 diabetes mellitus in non-diabetics: A systematic review and meta-analysis

Increasing epidemiological studies suggest that there is an association between vitamin D deficiency and risk of type 2 diabetes mellitus (T2DM). Therefore, randomized clinical trials (RCTs) have been performed to observe the effect of vitamin D supplementation on preventing T2DM, decreasing fasting plasma glucose (FPG) and improving insulin resistance to confirm the association between vitamin D and T2DM. However, the results of RCTs on controlling FPG level, improving insulin resistance and preventing T2DM in non-diabetics are inconsistent. In the present study, a systematic meta-analysis considering individual variation and intervention strategy was conducted to establish an objective and definitive conclusion. The results suggested that vitamin D supplementation had no significant effect on controlling FPG level, improving insulin resistance or preventing T2DM in non-diabetics in a pooled meta-analysis of 23 articles (containing 28 RCTs). However, stratified analysis indicated that supplementation of vitamin D had differential effects on FPG control, insulin sensitivity improvement and T2DM prevention in individuals with different baseline states: FPG was decreased for those with BMI <25 (P=0.048) or 20≤ 25(OH)D <30 ng/ml (P=0.002); insulin resistance was improved for those with 25(OH)D ≥30 ng/ml (P=0.021); and risk of T2DM was lower for pre-diabetic individuals (P=0.047) or for those with 25≤ BMI <30 (P=0.032). Additionally, the effect on T2DM prevention was improved when the supplement dose was >2,000 IU/day (P=0.047) and with intervention without calcium (P=0.047). Thus, further trials should focus on individual baselines and the supplementation strategy of vitamin D in the prevention of T2DM.

An Overview of Novel Dietary Supplements and Food Ingredients in Patients with Metabolic Syndrome and Non-Alcoholic Fatty Liver Disease

Metabolic syndrome (MetS) is characterized by interconnected factors related to metabolic disturbances, and is directly related to the occurrence of some diseases such as cardiovascular diseases and type 2 diabetes. MetS is described as one or both of insulin resistance and visceral adiposity, considered the initial causes of abnormalities that include hyperglycemia, elevated blood pressure, dyslipidemia, elevated inflammatory markers, and prothrombotic state, as well as polycystic ovarian syndrome in women. Other than in MetS, visceral adiposity and the pro-inflammatory state are also key in the development of non-alcoholic fatty liver disease (NAFLD), which is the most prevalent chronic liver disease in modern society. Both MetS and NAFLD are related to diet and lifestyle, and their treatment may be influenced by dietary pattern changes and the use of certain dietary supplements. This study aimed to review the role of food ingredients and supplements in the management of MetS and NAFLD specifically in human clinical trials. Moreover, bioactive compounds and polyunsaturated fatty acids (PUFAs) may be used as strategies for preventing the onset of and treatment of metabolic disorders, such as MetS and NAFLD, improving the inflammatory state and other comorbidities, such as obesity, dyslipidemias, and cardiovascular diseases (CVD).

Vitamin D levels do not predict the stage of hepatic fibrosis in patients with non-alcoholic fatty liver disease: A PRISMA compliant systematic review and meta-analysis of pooled data

AIM

To investigate the relationship between 25-hydroxyvitamin D [25(OH)D] levels and fibrosis stage in patients with non-alcoholic fatty liver disease (NAFLD).

METHODS

Two individual reviewers identified relevant studies using the PubMed, EMBASE, Cochrane, and Scopus databases. Inclusion criteria were as follows: (1) Studies that evaluated adults with NAFLD and serum or plasma 25(OH)D levels; and (2) assessed fibrosis stage using liver biopsy. A rigorous analysis yielded six articles as having sufficient data to employ in evaluating the association of serum vitamin D levels in patients with NAFLD based on their liver fibrosis stage by histopathological analysis. The lead investigators of each of the six studies were contacted and the data were collected. To meta-analyze vitamin D levels in F0-F2 vs F3-F4 fibrosis, a random-effects meta-analysis fit using restricted maximum likelihood was applied. To examine trends across each stage of fibrosis with respect to vitamin D levels, a meta-regression was performed. P < 0.05 was considered statistically significant.

RESULTS

A total of 937 subjects from six studies were included in the final analysis to evaluate the association of serum vitamin D levels in patients with NAFLD based on their liver fibrosis stage by histopathological analysis. The lead investigators of each of the six studies were contacted and the data were collected. First, the investigators performed a meta-analysis to compare serum vitamin D levels in patients with NAFLD with stage F0-F2 compared to F3-F4, which did not show significance [meta-estimate of the pooled mean difference = -0.86, P = 0.08 (-4.17, 2.46)]. A meta-regression evaluation of serum vitamin 25 (OH)D levels across the individual stages (F0-F4) of fibrosis did not show an association for the six included studies.

CONCLUSION

Low vitamin D status is not associated with higher stages of liver fibrosis in patients with NAFLD.