Association between dietary iron intake and the prevalence of nonalcoholic fatty liver disease: A cross-sectional study

Targeting the regulation of iron homeostasis as a potential therapeutic strategy for nonalcoholic fatty liver disease

With aging and the increasing incidence of obesity, nonalcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease worldwide. NAFLD mainly includes simple hepatic steatosis, nonalcoholic steatohepatitis (NASH), liver fibrosis and hepatocellular carcinoma (HCC). An imbalance in hepatic iron homeostasis is usually associated with the progression of NAFLD and induces iron overload, reactive oxygen species (ROS) production, and lipid peroxide accumulation, which leads to ferroptosis. Ferroptosis is a unique type of programmed cell death (PCD) that is characterized by iron dependence, ROS production and lipid peroxidation. The ferroptosis inhibition systems involved in NAFLD include the solute carrier family 7 member 11 (SLC7A11)/glutathione (GSH)/glutathione peroxidase 4 (GPX4) and ferroptosis suppressor protein 1 (FSP1)/coenzyme Q10 (CoQ10)/nicotinamide adenine dinucleotide phosphate (NADPH) regulatory axes. The main promotion system involved is the acyl-CoA synthetase long-chain family (ACSL4)/arachidonic lipoxygenase 15 (ALOX15) axis. In recent years, an increasing number of studies have focused on the multiple roles of iron homeostasis imbalance and ferroptosis in the progression of NAFLD. This review highlights the latest studies about iron homeostasis imbalance- and ferroptosis-associated NAFLD, mainly including the physiology and pathophysiology of hepatic iron metabolism, hepatic iron homeostasis imbalance during the development of NAFLD, and key regulatory molecules and roles of hepatic ferroptosis in NAFLD. This review aims to provide innovative therapeutic strategies for NAFLD.

Hepatocyte programmed cell death: the trigger for inflammation and fibrosis in metabolic dysfunction-associated steatohepatitis

By replacing and removing defective or infected cells, programmed cell death (PCD) contributes to homeostasis maintenance and body development, which is ubiquitously present in mammals and can occur at any time. Besides apoptosis, more novel modalities of PCD have been described recently, such as necroptosis, pyroptosis, ferroptosis, and autophagy-dependent cell death. PCD not only regulates multiple physiological processes, but also participates in the pathogenesis of diverse disorders, including metabolic dysfunction-associated steatotic liver disease (MASLD). MASLD is mainly classified into metabolic dysfunction-associated steatotic liver (MASL) and metabolic dysfunction-associated steatohepatitis (MASH), and the latter putatively progresses to cirrhosis and hepatocellular carcinoma. Owing to increased incidence and obscure etiology of MASH, its management still remains a tremendous challenge. Recently, hepatocyte PCD has been attracted much attention as a potent driver of the pathological progression from MASL to MASH, and some pharmacological agents have been proved to exert their salutary effects on MASH partly via the regulation of the activity of hepatocyte PCD. The current review recapitulates the pathogenesis of different modalities of PCD, clarifies the mechanisms underlying how metabolic disorders in MASLD induce hepatocyte PCD and how hepatocyte PCD contributes to inflammatory and fibrotic progression of MASH, discusses several signaling pathways in hepatocytes governing the execution of PCD, and summarizes some potential pharmacological agents for MASH treatment which exert their therapeutic effects partly via the regulation of hepatocyte PCD. These findings indicate that hepatocyte PCD putatively represents a new therapeutic point of intervention for MASH.

A high reticulocyte count is a risk factor for the onset of metabolic dysfunction-associated steatotic liver disease: Cross-sectional and prospective studies of data of 310,091 individuals from the UK Biobank

Background and Aims: Metabolic dysfunction-associated steatotic liver disease (MASLD) poses a considerable health risk. Nevertheless, its risk factors are not thoroughly comprehended, and the association between the reticulocyte count and MASLD remains uncertain. This study aimed to explore the relationship between reticulocyte count and MASLD. Methods: A total of 310,091 individuals from the UK Biobank were included in this cross-sectional study, and 7,316 individuals were included in this prospective study. The cross-sectional analysis categorized reticulocyte count into quartiles, considering the sample distribution. Logistic regression models examined the connection between reticulocyte count and MASLD. In the prospective analysis, Cox analysis was utilized to investigate the association. Results: Our study findings indicate a significant association between higher reticulocyte count and an elevated risk of MASLD in both the cross-sectional and prospective analyses. In the cross-sectional analysis, the adjusted odds ratios (ORs) of MASLD increased stepwise over reticulocyte count quartiles (quartile 2: OR 1.22, 95% CI 1.17-1.28, p < 0.001; quartile 3: OR 1.44; 95% CI 1.38-1.51, p < 0.001; quartile 4: OR 1.66, 95% CI 1.59-1.74, p < 0.001). The results of prospective analyses were similar. Conclusion: Increased reticulocyte count was independently associated with a higher risk of MASLD. This discovery offers new insights into the potential of reticulocytes as biomarkers for MASLD.

Low-Iron Diet-Induced Fatty Liver Development Is Microbiota Dependent and Exacerbated by Loss of the Mitochondrial Iron Importer Mitoferrin2

Iron deficiency is the number one nutritional problem worldwide. Iron uptake is regulated at the intestine and is highly influenced by the gut microbiome. Blood from the intestines drains directly into the liver, informing iron status and gut microbiota status. Changes in either iron or the microbiome are tightly correlated with the development of metabolic dysfunction-associated steatotic liver disease (MASLD). To investigate the underlying mechanisms of the development of MASLD that connect altered iron metabolism and gut microbiota, we compared specific pathogen free (SPF) or germ-free (GF) mice, fed a normal or low-iron diet. SPF mice on a low-iron diet showed reduced serum triglycerides and MASLD. In contrast, GF low-iron diet-fed mice showed increased serum triglycerides and did not develop hepatic steatosis. SPF mice showed significant changes in liver lipid metabolism and increased insulin resistance that was dependent upon the presence of the gut microbiota. We report that total body loss of mitochondrial iron importer Mitoferrin2 (Mfrn2-/-) exacerbated the development of MASLD on a low-iron diet with significant lipid metabolism alterations. Our study demonstrates a clear contribution of the gut microbiome, dietary iron, and Mfrn2 in the development of MASLD and metabolic syndrome.

Dietary composition and its association with metabolic dysfunction-associated fatty liver disease among Chinese adults: A cross-sectional study

BACKGROUND AND STUDY AIMS

Metabolic dysfunction-associated fatty liver disease (MAFLD) has become the most common cause of chronic liver disease worldwide. Diet plays a critical role in the prevention and treatment of MAFLD. Our hypothesis was that the intake of some macronutrients, vitamins, or mineral elements is associated with MAFLD.

PATIENTS AND METHODS

Patients with MAFLD can be diagnosed based on the evidence of hepatic steatosis and if they meet any of the three additional criteria of overweight/obesity, diabetes mellitus, or metabolic dysregulation. Diets were recorded using photographs and diaries of meals for seven consecutive days. The consumed dietary composition was compared with the recommended intake according to the China Food Composition Tables (Standard Edition) version 2019 and the Chinese Dietary Reference Intakes version 2013, and its association with MAFLD was assessed by logistical regression analyses.

RESULTS

A total of 229 MAFLD patients and 148 healthy controls were included in this study. MAFLD patients, compared with that by non-MAFLD participants, consumed more polyunsaturated fatty acids (PUFAs) (p < 0.001), vitamin E (p < 0.001), and iron (p = 0.008). The intake of PUFAs (OR = 1.070, 95 % CI: 1.017-1.127, p = 0.009) and vitamin E (OR = 1.100, 95 % CI: 1.018-1.190, p = 0.016) was positively associated with MAFLD. In addition, the percentages of individuals who consumed PUFAs (p = 0.006), vitamin E (p < 0.001), or iron (p = 0.046) above the recommended intake were higher among the individuals with MAFLD. Daily intake of PUFAs > 11 % (OR = 2.328, 95 % CI: 1.290-4.201, p = 0.005) and vitamin E > 14 mg (OR = 2.189, 95 % CI: 1.153-4.158, p = 0.017) was positively correlated with MAFLD.

CONCLUSIONS

Patients with MAFLD consumed more PUFAs, vitamin E, and iron in their daily diet. Excessive consumption of PUFAs and vitamin E might be independent risk factors for the incidence of MAFLD.

Supplementation of Micro- and Macronutrients-A Role of Nutritional Status in Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) is a condition in which the pathological cumulation of fat with coexisting inflammation and damage of hepatic cells leads to progressive dysfunctions of the liver. Except for the commonly well-known major causes of NAFLD such as obesity, dyslipidemia, insulin resistance, or diabetes, an unbalanced diet and imbalanced nutritional status should also be taken into consideration. In this narrative review, we summarized the current knowledge regarding the micro- and macronutrient status of patients suffering from NAFLD considering various diets and supplementation of chosen supplements. We aimed to summarize the knowledge indicating which nutritional impairments may be associated with the onset and progression of NAFLD at the same time evaluating the potential therapy targets that could facilitate the healing process. Except for the above-mentioned objectives, one of the most important aspects of this review was to highlight the possible strategies for taking care of NAFLD patients taking into account the challenges and opportunities associated with the micronutrient status of the patients. The current research indicates that a supplementation of chosen vitamins (e.g., vitamin A, B complex, C, or D) as well as chosen elements such as zinc may alleviate the symptoms of NAFLD. However, there is still a lack of sufficient data regarding healthy ranges of dosages; thus, further research is of high importance in this matter.

Association Between Non-alcoholic Fatty Liver Disease and Heavy Metal Exposure: a Systematic Review

Non-alcoholic fatty liver disease (NAFLD) is a debilitating disease with adverse effects including cirrhosis and hepatocellular carcinoma. Heavy metals can cause severe dysfunction in different body organs including the liver. This review offers the study regarding the positive or negative association between heavy metals exposure and non-alcoholic fatty liver disease. The method used in this study is a systematic review based on searching in the PubMed, Scopus, and Science direct databases with the keywords of fatty liver, non-alcohol fatty liver, heavy metal, mercury, cadmium, arsenic, chromium, thallium, lead, iron, zinc, and nickel. There were 2200 articles searched in databases, and after assessment, 28 articles were selected. Positive association is established between arsenic, cadmium, iron, lead, mercury, and fatty liver disease. A negative relationship is found between zinc, copper, and progressive fatty liver disease. Furthermore, laboratory methods for NAFLD diagnosis were examined according to the obtained manuscripts. Among the different diagnostic methods, magnetic resonance imaging (MRI) is a sensitive method.

Metabolic dysfunction-associated steatotic liver disease: ferroptosis related mechanisms and potential drugs

Metabolic dysfunction-associated steatotic liver disease (MASLD) is considered a "multisystem" disease that simultaneously suffers from metabolic diseases and hepatic steatosis. Some may develop into liver fibrosis, cirrhosis, and even hepatocellular carcinoma. Given the close connection between metabolic diseases and fatty liver, it is urgent to identify drugs that can control metabolic diseases and fatty liver as a whole and delay disease progression. Ferroptosis, characterized by iron overload and lipid peroxidation resulting from abnormal iron metabolism, is a programmed cell death mechanism. It is an important pathogenic mechanism in metabolic diseases or fatty liver, and may become a key direction for improving MASLD. In this article, we have summarized the physiological and pathological mechanisms of iron metabolism and ferroptosis, as well as the connections established between metabolic diseases and fatty liver through ferroptosis. We have also summarized MASLD therapeutic drugs and potential active substances targeting ferroptosis, in order to provide readers with new insights. At the same time, in future clinical trials involving subjects with MASLD (especially with the intervention of the therapeutic drugs), the detection of serum iron metabolism levels and ferroptosis markers in patients should be increased to further explore the efficacy of potential drugs on ferroptosis.

Ferroptosis in non-alcoholic liver disease: Molecular mechanisms and therapeutic implications

Ferroptosis refers to a novel modality of regulated cell death characterized by excessive iron accumulation and overwhelming lipid peroxidation, which takes an important part in multiple pathological processes associated with cell death. Considering the crucial roles of the liver in iron and lipid metabolism and its predisposition to oxidative insults, more and more studies have been conducted to explore the relationship between ferroptosis and various liver disorders, including non-alcoholic fatty liver disease (NAFLD). With increased morbidity and high mortality rates, NAFLD has currently emerged as a global public health issue. However, the etiology of NAFLD is not fully understood. In recent years, an accumulating body of evidence have suggested that ferroptosis plays a pivotal role in the pathogenesis of NAFLD, but the precise mechanisms underlying how ferroptosis affects NAFLD still remain obscure. Here, we summarize the molecular mechanisms of ferroptosis and its complicated regulation systems, delineate the different effects that ferroptosis exerts in different stages of NAFLD, and discuss some potential effective therapies targeting ferroptosis for NAFLD treatment, which putatively points out a novel direction for NAFLD treatment.

Intrahepatic Fat Content and COVID-19 Lockdown in Adults with NAFLD and Metabolic Syndrome

Background: COVID-19 lockdowns had a significant impact on people’s health, triggering levels of anxiety, perceived stress, and changes in food and nutritional status. Objectives: To assess the changes in dietary habits, metabolic syndrome (MetS) and liver parameters before and after the COVID-19 lockdown according to changes in intrahepatic fat content in adults with non-alcoholic fatty liver disease (NAFLD) and MetS. Design: Pre- and post-lockdown observation of the COVID-19 lockdown on fifty-nine 40–60-year-old participants with MetS and NAFLD, in a parallel group, randomised experiment intended to treat NAFLD. Methods: Anthropometrics, liver and MetS biochemical parameters, intrahepatic fat content by abdominal magnetic resonance imaging, and dietary assessment using a validated 148-item Food Frequency Questionnaire were collected pre-COVID-19 lockdown and post-lockdown. Results: COVID-19 lockdown led to negative changes in the liver of patients with NAFLD and MetS, with weight gain and increases in glycemia, ALT and intrahepatic fat content post lockdown. Participants with worsened liver status had low consumption of fibre, cheese, nuts and coffee, and high consumption of sweets and pastries. Participants who improved liver status ameliorated ALT values, waist circumference, and intrahepatic fat content, assessed by magnetic resonance imaging post-lockdown. Conclusions: The maintenance of healthy lifestyle habits is vital, especially for populations with NAFLD and MetS, to reduce unhealthy lifestyle patterns displayed during lockdown.

An overview of ferroptosis in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is a public health problem associated with high mortality and high morbidity rates worldwide. Presently, its complex pathophysiology is still unclear, and there is no specific drug to reverse NAFLD. Ferroptosis is an iron-dependent and non-apoptotic form of cell death characterized by the iron-induced accumulation of lipid reactive oxygen species (ROS), which damage nucleic acids, proteins, and lipids; generate intracellular oxidative stress; and ultimately cause cell death. Emerging evidence indicates that ferroptosis is involved in the progression of NAFLD, although the mechanism of action of ferroptosis in NAFLD is still poorly understood. Herein, we summarize the mechanism of action of ferroptosis in certain diseases, especially in the pathogenesis of NAFLD, and discuss the potential therapeutic approaches currently used to treat NAFLD. This review also highlights further directions for the treatment and prevention of NAFLD and related diseases.

Ferroptosis and metabolic dysfunction-associated fatty liver disease: Is there a link?

Non-alcoholic fatty liver disease (NAFLD), recently re-defined and re-classified as metabolic dysfunction-associated fatty liver disease (MAFLD), has become increasingly prevalent and emerged as a public health problem worldwide. To date, the precise pathogenic mechanisms underpinning MAFLD are not entirely understood, and there is no effective pharmacological therapy for NAFLD/MAFLD. As a newly discovered form of iron-dependent programmed cell death, ferroptosis can be involved in the development and progression of various chronic diseases, but the pathogenic connections and mechanisms that link MAFLD and ferroptosis have not been fully elucidated. The main characteristics of ferroptosis are the accumulation of lipid peroxides and reactive oxygen species. In this brief narrative review, the mechanisms of ferroptosis and its putative pathogenic role in MAFLD are discussed to highlight potential new research directions and ideas for the prevention and treatment of MAFLD.

Effect of Structured Diabetes Education on Diabetic Angiopathies Among Kidney Transplant Recipients With Posttransplant Diabetes: Kuwait Experience

OBJECTIVES

Diabetes knowledge among kidney transplant recipients with posttransplant diabetes has not been exhaustively assessed. Here, we evaluated the effects of structured diabetes education on development of diabetic micro- and macroangiopathies in kidney transplant patients with posttransplant diabetes.

MATERIALS AND METHODS

This prospective randomized controlled study categorized 210 renal transplant patients with posttransplant diabetes mellitus into 2:1 groups according to type of diabetes education. Group 1 (n = 140) received structured education, and group 2 (n = 70) received conventional education. Patient data were collected through patient identification and metabolic control parameter forms.

RESULTS

Most patients in groups 1 and 2, respectively, were Kuwaiti (60.7% vs 58.6%), men (57.9% vs 68.6%), and had high school-level education (43.6% vs 48.6%). Chronic glomerulonephritis was the original disease in 36.4% versus 35.4% of patients. Most patients (72.8% vs 78.6% in group 1 vs 2) received pretransplant hemodialysis. At study start, the rate of patients with diabetic neuropathy was comparable between groups (32.4% vs 27.9%). Moreover, after completion of 24 months of education, neurological evaluation by electromyograph and nerve conduction studies did not show any significant differences between the groups (P > .05). Similarly, the number of patients with fundus imaging showing retinopathy was comparable between groups at start and end of study (P > .05). Although macroangiopathic events were higher in group 1, this finding was not significant (P > .05). However, although the percentage of patients with nephropathy was comparable in both groups at start of study, the percentage decreased significantly in group 1 at 24 months after completion of education compared with group 2 and baseline value (P = .016).

CONCLUSIONS

Structured diabetes education was associated with reduced diabetic nephropathy but had no significant effects on other micro- or macroangiopathies. However, we recommend education for all kidney transplant recipients with diabetes.

Effect of Turmeric Supplementation on Blood Pressure and Serum Levels of Sirtuin 1 and Adiponectin in Patients with Nonalcoholic Fatty Liver Disease: A Double-Blind, Randomized, Placebo-Controlled Trial

Nonalcoholic fatty liver disease (NAFLD) is commonly associated with obesity. This randomized, double-blind, placebo-controlled trial aimed to evaluate the effects of turmeric on serum adiponectin and sirtuin 1 (SIRT1) levels, blood pressure, and body mass index (BMI) in patients with NAFLD. A total of 46 eligible patients with NAFLD (BMI, 25.0∼39.9 kg/m²) were randomly allocated to turmeric and placebo groups using block randomization. The turmeric group (n=23) was administered 3,000 mg/d turmeric powder in six 500-mg capsules for 12 weeks, whereas the placebo group (n=23) was administered six placebo capsules/d for 12 weeks. Body weight, BMI, serum SIRT1 and adiponectin levels, and systolic and diastolic blood pressures were measured at baseline and 12 weeks after intervention. Serum SIRT1 levels increased significantly in the turmeric group compared with the placebo group. Additionally, participants in the turmeric group exhibited lower weight, BMI, and systolic blood pressure after 12 weeks of intervention compared with the baseline. Turmeric effectively improved SIRT1 levels in patients with NAFLD compared with the placebo. The efficacy of turmeric might increase with long-term use at higher doses.

Genetic effects of iron levels on liver injury and risk of liver diseases: A two-sample Mendelian randomization analysis

Background and aims

Although iron homeostasis has been associated with liver function in many observational studies, the causality in this relationship remains unclear. By using Mendelian Randomization analyses, we aimed to evaluate the genetic effects of increased systemic iron levels on the risk of liver injury and various liver diseases. Moreover, in light of the sex-dependent iron regulation in human beings, we further estimated the sex-specific effect of iron levels in liver diseases.

Methods

Independent single nucleotide polymorphisms associated with systemic iron status (including four indicators) at the genome-wide significance level from the Genetics of Iron Status (GIS) Consortium were selected as instrumental variables. Summary data for six liver function biomarkers and five liver diseases were obtained from the UK Biobank, the Estonian Biobank, the eMERGE network, and FinnGen consortium. Mendelian Randomization assessment of the effect of iron on liver function and liver diseases was conducted.

Results

Genetically predicted iron levels were positively and significantly associated with an increased risk of different dimensions of liver injury. Furthermore, increased iron status posed hazardous effects on non-alcoholic fatty liver disease, alcoholic liver disease, and liver fibrosis/cirrhosis. Sex-stratified analyses indicated that the hepatoxic role of iron might exist in NAFLD and liver fibrosis/cirrhosis development among men. No significantly causal relationship was found between iron status and viral hepatitis.

Conclusion

Our study adds to current knowledge on the genetic role of iron in the risk of liver injury and related liver diseases, which provides clinical and public health implications for liver disease prevention as iron status can be modified.

The Relationship of Hyperferritinemia to Metabolism and Chronic Complications in Type 2 Diabetes

AIM

Elevated serum ferritin has been found to be closely related to type 2 diabetes mellitus. This study aimed to explore the relationship of high serum ferritin to metabolism and chronic complications in type 2 diabetes.

METHODS

This was a cross-sectional study. A total of 330 type 2 diabetes patients who visited an endocrine clinic were included for the analysis. Serum ferritin and metabolic parameters were recorded. The prevalence of chronic diabetic complications was evaluated. Based on serum ferritin, participants were divided into hyperferritinemia and normal-ferritin groups. Metabolic parameters and prevalence of chronic diabetic complications were compared. The relationship between hyperferritinemia and chronic diabetic complications was explored with multivariate logistic regression models. Data were statistically analyzed by sex.

RESULTS

Compared with the normal-ferritin group, the hyperferritinemia group showed higher levels of the serum inflammatory marker CRP and higher prevalence of diabetic retinopathy (DR) and coronary heart disease (CHD), regardless of sex (p<0.05). Moreover, male patients with hyperferritinemia had increased serum triglyceride, alanine transferase, γ-glutamyltranspeptidase, urea nitrogen, creatinine, and uric acid and higher prevalence of microalbuminuria (p<0.01). After controlling for demographics and metabolic profiles, hyperferritinemia remained an independent risk factor of DR (male OR 3.957, 95% CI 1.559-10.041, p=0.004; female OR 2.474, 95% CI 1.127-5.430, p=0.024) and CHD (male OR 2.607, 95% CI 1.087-6.257, p=0.032; female OR 2.293, 95% CI 1.031-5.096, p=0.042).

CONCLUSION

This study found that hyperferritinemia was associated with increased CRP and higher prevalence of DR and CHD in type 2 diabetes. In men, high serum ferritin was also associated with dyslipidemia, hepatic dysfunction, and microalbuminuria.

Association Between Dietary Fiber Intake and Non-alcoholic Fatty Liver Disease in Adults

Background: Evidence on the association of non-alcoholic fatty liver disease (NAFLD), a public health concern, with dietary fiber intake is inconsistent.

Objective: To investigate the relationship between dietary fiber intake from different sources and NAFLD risk in US adults.

Methods: Data were collected from the 2007–2014 National Health and Nutrition Examination Survey. NAFLD was defined as a United States Fatty Liver Index ≥30, and dietary fiber intake was assessed through two 24-h dietary recall interviews. Logistic regression and restricted cubic spline models were used to explore the relationship of dietary intakes of total, cereal, fruit, and vegetable fiber with NAFLD risk.

Results: A total of 6,613 participants, aged more than 20 years, were included in this study. After adjusting for multiple confounding factors, the odds ratios and 95% confidence intervals of NAFLD for the highest quartile vs. lowest quartile intakes of total, cereal, fruit, and vegetable fiber were 0.12 (0.08–0.16), 0.25 (0.19–0.33), 0.41 (0.33–0.52), and 0.42 (0.32–0.56), respectively. In stratified analyses by sex and age, statistically significant negative associations of dietary intakes of total, cereal, fruit, and vegetable fiber with NAFLD risk were observed in all participants. Dose-response analysis indicated a non-linear correlation between NAFLD risk and dietary intake of total fiber, whereas the relationship was linear for cereal, fruit, and vegetable fiber intakes.

Conclusion: Total, cereal, fruit, and vegetable fiber intakes exhibit negative correlations with NAFLD risk in the general adult population in the United States.