Significance of exercise in nonalcoholic fatty liver disease in men: a community-based large cross-sectional study

Circadian Deregulation: Back Facing the Sun Toward Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD) Development

Earth's rotation around its axis has pressured its inhabitants to adapt to 24 h cycles of day and night. Humans adapted their own circadian rhythms to the Earth's rhythms with a light-aligned awake-sleep cycle. As a consequence, metabolism undergoes drastic changes throughout the circadian cycle and needs plasticity to cope with opposing conditions in the day (when there is an increase in energy demands and food availability), and during the night (when prolonged fasting couples with cyclic changes in the energy demands across the sleep stages). In the last century, human behavior changed dramatically with a disregard for the natural circadian cycles. This misalignment in sleep and eating schedules strongly modulates the metabolism and energy homeostasis, favoring the development of obesity, metabolic syndrome, and metabolic dysfunction-associated steatotic liver disease (MASLD). This review summarizes the effects of circadian disruption, with a particular focus on the feeding and sleep cycles in the development of MASLD and hepatocellular carcinoma.

Night shift-induced circadian disruption: links to initiation of non-alcoholic fatty liver disease/non-alcoholic steatohepatitis and risk of hepatic cancer

The circadian system plays a crucial role in regulating metabolic homeostasis at both systemic and tissue levels by synchronizing the central and peripheral clocks with exogenous time cues, known as zeitgebers (such as the light/dark cycle). Our body's behavioral rhythms, including sleep-wake cycles and feeding-fasting patterns, align with these extrinsic time cues. The body cannot effectively rest and repair itself when circadian rhythms are frequently disrupted. In many shift workers, the internal rhythms fail to fully synchronize with the end and start times of their shifts. Additionally, exposure to artificial light at night (LAN), irregular eating patterns, and sleep deprivation contribute to circadian disruption and misalignment. Shift work and jet lag disrupt the normal circadian rhythm of liver activity, resulting in a condition known as "circadian disruption". This disturbance adversely affects the metabolism and homeostasis of the liver, contributing to excessive fat accumulation and abnormal liver function. Additionally, extended working hours, such as prolonged night shifts, may worsen the progression of non-alcoholic fatty liver disease (NAFLD) toward non-alcoholic steatohepatitis (NASH) and increase disease severity. Studies have demonstrated a positive correlation between night shift work (NSW) and elevated liver enzymes, indicative of hepatic metabolic dysfunction, potentially increasing the risk of hepatocellular carcinoma (HCC) related to NAFLD. This review consolidates research findings on circadian disruption caused by NSW, late chronotype, jet lag, and social jet lag, drawing insights from studies involving both humans and animal models that investigate the effects of these factors on circadian rhythms in liver metabolism.

Exercise, weight maintenance, and nonalcoholic fatty liver disease risk: a Chinese cohort study

Background: Exercise has been reported to be associated with a reduced risk of nonalcoholic fatty liver disease (NAFLD), but there is no consensus on the role of weight changes in this association. This study aims to investigate whether the impact of exercise on NAFLD is mainly dependent on weight changes or is inherent to exercise itself. Methods: The study recruited 1671 Chinese NAFLD-free adults in 2019, and collected their exercise habits as well as 3 years of medical examination data including anthropometric measurements, blood biochemistry parameters, and liver ultrasound results. Univariate and multivariate logistic regression models were employed to examine the impact of exercise habits on NAFLD risk, with mediation analysis utilized to estimate the magnitude of the role of weight maintenance in the association between exercise and NAFLD. Results: After adjusting for confounders, moderate to high-intensity exercisers were 1.56 times (95% CIs = 1.09-2.22) more likely to successfully control their body weight, and therefore the weight-controlled group had a lower NAFLD risk of 34.9% (95% CIs = 21.8%-56.0%) compared to the weight-gain group. Mediation analysis reveals that exercise can significantly reduce the risk of NAFLD both through weight maintenance (37.1%) and independent of weight maintenance (62.9%). Conclusion: It might be more crucial to emphasize the adoption of regular moderate to high-intensity exercise for preventing NAFLD in the general population, rather than solely focusing on weight maintenance.

A Meta-Analysis of Sleep Disorders and Nonalcoholic Fatty Liver Disease: Potential Causality and Symptom Management

Nonalcoholic fatty liver disease is a type of metabolic disease, and recent research indicates that it may be associated with sleep disorders. We conducted a meta-analysis of current studies to estimate the associations between nonalcoholic fatty liver disease and sleep situation, including sleep duration, daytime sleepiness, and sleep disorder. This study follows the checklist of the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA). Articles in the recent 10 years were searched from five databases. Eighteen articles, which met the eligibility criteria, were included in this meta-analysis. The results show that patients with nonalcoholic fatty liver disease have a shorter sleep duration and higher Epworth Sleepiness Scale score. Patients with short sleep duration (≤6 hours per night) or with obstructive sleep apnea have a higher risk of nonalcoholic fatty liver disease. In conclusion, there is a significant association between nonalcoholic fatty liver disease and sleep disorders in the included studies. In addition, patients with nonalcoholic fatty liver disease may have more severe daytime sleepiness and shorter sleep duration. More attention should be paid to the sleep situation of nonalcoholic fatty liver disease patients to potentially slow the disease progression.

Exercise inhibits JNK pathway activation and lipotoxicity via macrophage migration inhibitory factor in nonalcoholic fatty liver disease

The macrophage migration inhibitory factor (MIF) expressed in hepatocytes can limit steatosis during obesity. Lipotoxicity in nonalcoholic fatty liver disease is mediated in part by the activation of the stress kinase JNK, but whether MIF modulates JNK in lipotoxicity is unknown. In this study, we investigated the role of MIF in regulating JNK activation and high-fat fostered liver lipotoxicity during simultaneous exercise treatment. Fifteen mice were equally divided into three groups: normal diet, high-fat diet, and high-fat and exercise groups. High-fat feeding for extended periods elicited evident hyperlipemia, liver steatosis, and cell apoptosis in mice, with inhibited MIF and activated downstream MAPK kinase 4 phosphorylation and JNK. These effects were then reversed following prescribed swimming exercise, indicating that the advent of exercise could prevent liver lipotoxicity induced by lipid overload and might correlate to the action of modulating MIF and its downstream JNK pathway. Similar detrimental effects of lipotoxicity were observed in in vitro HepG2 cells palmitic acid treatment. Suppressed JNK reduced the hepatocyte lipotoxicity by regulating the BCL family, and the excess JNK activation could also be attenuated through MIF supplementation or exacerbated by MIF siRNA administration. The results found suggest that exercise reduces lipotoxicity and inhibits JNK activation by modulating endogenous hepatic MIF in NAFLD. These findings have clinical implications for the prevention and intervention of patients with immoderate diet evoked NAFLD.

Clinical practice advice on lifestyle modification in the management of nonalcoholic fatty liver disease in Japan: an expert review

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver diseases worldwide, including in Japan. The Japanese Society of Gastroenterology (JSGE) and the Japanese Society of Hepatology (JSH) have established the Japanese NAFLD/NASH guidelines in 2014 and revised these guidelines in 2020. As described in these guidelines, weight reduction by diet and/or exercise therapy is important for the treatment of NAFLD patients. The I148M single nucleotide polymorphism (rs738409 C > G) of PNPLA3 (patatin-like phospholipase domain-containing 3 protein) is widely known to be associated with the occurrence and progression of NAFLD. In the Japanese, the ratio of PNPLA3 gene polymorphisms found is approximately 20%, which is higher than that found in Westerners. In addition, the ratio of lean NAFLD patients is also higher in Japan than in Western countries. Therefore, the method for lifestyle guidance for the NAFLD patients in Japan would be different from that for the people in Western countries. The problems in the treatment of NAFLD patients include alcohol consumption and sarcopenia. Therefore, guidelines that can help clinicians treat Japanese patients with NAFLD are needed. In this expert review, we summarize evidence-based interventions for lifestyle modification (diet, exercise, alcohol, and sarcopenia) for the treatment of patients with NAFLD, especially from Japan and Asian countries.

Role of circadian rhythm and autonomic nervous system in liver function: a hypothetical basis for improving the management of hepatic encephalopathy

Hepatic encephalopathy (HE) is a common, incapacitating complication of cirrhosis that affects many patients with cirrhosis. Although several therapies have proven effective in the treatment and prevention of this condition, several patients continue to suffer from covert disease or episodes of relapse. The circadian rhythm has been demonstrated to be pivotal for many body functions, including those of the liver. Here, we explore the impact of circadian rhythm-dependent signaling on the liver and discuss the evidence of its impact on liver pathology and metabolism. We describe the various pathways through which circadian influences are mediated. Finally, we introduce a novel method for improving patient response to drugs aimed at treating HE by utilizing the circadian rhythm. A digital system that introduces a customization-based technique for improving the response to therapies is presented as a hypothetical approach for improving the effectiveness of current medications used for the treatment of recurrent and persistent hepatic encephalopathy.

Aerobic Exercise in the Management of Metabolic Dysfunction Associated Fatty Liver Disease

Sedentarism is the pandemic of modern times. It is associated with several medical conditions including obesity, type 2 diabetes mellitus, cardiovascular diseases and also liver disease, particularly metabolic dysfunction associated fatty liver disease (MAFLD). In an era when MAFLD is the most prevalent chronic liver disease worldwide, whilst no pharmacological therapy has been approved for it, exercise has proved to be effective in improving liver steatosis. Interestingly, exercise decreases liver fat even in the absence of weight loss. The challenge for the clinician is to motivate the obese patient with MAFLD, and associated co-morbidities, who has crystallized a sedentary behavior, at times when every need is at the distance of a click on the Internet, and the entire world can be visited behind a screen. In this review, the aggregate evidence on the mechanisms and effects of exercise in the management of MAFLD is summarized, with simple recommendations for everyday clinical practice.

Physiopathology of Lifestyle Interventions in Non-Alcoholic Fatty Liver Disease (NAFLD)

Non-alcoholic fatty liver disease (NAFLD) is a major health problem, and its prevalence has increased in recent years. Diet and exercise interventions are the first-line treatment options, with weight loss via a hypocaloric diet being the most important therapeutic target in NAFLD. However, most NAFLD patients are not able to achieve such weight loss. Therefore, the requisite is the investigation of other effective therapeutic approaches. This review summarizes research on understanding complex pathophysiology underlying dietary approaches and exercise interventions with the potential to prevent and treat NAFLD.

A Pilot Study Assessing the Possible Combined Effect of Physical Activity and PNPLA3 rs738409 Polymorphism on the Risk for Non-Alcoholic Fatty Liver Disease in the Japanese Elderly General Population

PURPOSE

The patatin-like phospholipase domain containing protein 3 (PNPLA3) rs738409 polymorphism (c.444C>G) is the most well-known genetic risk factor for non-alcoholic fatty liver disease (NAFLD), but whether or not physical activity influences the association between the PNPLA3 genotype and risk of NAFLD is unclear.

PATIENTS AND METHODS

A retrospective longitudinal analysis was conducted among 352 Japanese subjects. Each type of physical activity was assigned a metabolic equivalent (MET), and the subjects were classified into sedentary, low or high groups using the "METS*T" (METs × hours per week) value of 5 or 21 as a threshold.

RESULTS

Among the PNPLA3 G/G genotype carriers, the high and low METS*T groups had a lower risk of NAFLD than the sedentary METS*T group (odds ratio [95% confidence interval]: 0.14 [0.02-0.99] and 0.16 [0.03-1.04], respectively). Furthermore, the PNPLA3 C/C or C/G genotype carriers showed no significant difference in the risk of NAFLD among the three METS*T groups.

CONCLUSION

The PNPLA3 rs738409 genotype may be associated with the beneficial effects of physical activity on the risk of NAFLD among elderly Japanese individuals. Further comprehensive investigations are therefore needed to verify the preliminary results.

The changing epidemiology of liver diseases in the Asia-Pacific region

This Review presents current epidemiological trends of the most common liver diseases in Asia-Pacific countries. Hepatitis B virus (HBV) remains the primary cause of cirrhosis; despite declining prevalence in most Asian nations, this virus still poses a severe threat in some territories and regions. Mortality resulting from HBV infection is declining as a result of preventive measures and antiviral treatments. The epidemiological transition of hepatitis C virus (HCV) infection has varied in the region in the past few decades, but the medical burden of infection and the prevalence of its related cancers are increasing. The lack of licensed HCV vaccines highlights the need for novel treatment strategies. The prevalence of nonalcoholic fatty liver disease (NAFLD) has risen in the past decade, mostly owing to increasingly urbanized lifestyles and dietary changes. Alternative herbal medicine and dietary supplements are major causes of drug-induced liver injury (DILI) in some countries. Complications arising from these chronic liver diseases, including cirrhosis and liver cancer, are therefore emerging threats in the Asia-Pacific region. Key strategies to control these liver diseases include monitoring of at-risk populations, implementation of national guidelines and increasing public and physician awareness, in concert with improving access to health care.

Role of the Circadian Clock in the Metabolic Syndrome and Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in industrialized nations and is strongly associated with the metabolic syndrome. The prevalence of NAFLD continues to rise along with the epidemic of the metabolic syndrome. Metabolic homeostasis is linked to the circadian clock (rhythm), with multiple signaling pathways in organs regulated by circadian clock genes, and recent studies of circadian clock gene functions suggest that disruption of the circadian rhythm is associated with significant morbidity and mortality, including the metabolic syndrome. In the industrialized world, various human behaviors and activities such as work and eating patterns, jet lag, and sleep deprivation interfere with the circadian rhythm, leading to perturbations in metabolism and development of the metabolic syndrome. In this review, we discuss how disruption of the circadian rhythm is associated with various metabolic conditions that comprise the metabolic syndrome and NAFLD.

No association between fruits or vegetables and non-alcoholic fatty liver disease in middle-aged men and women

OBJECTIVE

It has been hypothesized that fruit and vegetable intake is inversely associated with non-alcoholic fatty liver (NAFLD). However, some studies have speculated that fruit intake might be positively associated with NAFLD owing to the fructose content of the fruit. This might cause consumers to hesitate consuming fruit. The aim of this study was to assess the association between fruit and vegetable consumption and NAFLD.

METHODS

This was a cross-sectional study of 977 men and 1467 women, 40 to 69 y of age without current liver disease other than NAFLD and who did not report excess alcohol intake (i.e., ≥30 g/d in men and ≥20 g/d in women). Dietary intake was assessed using a validated diet history questionnaire. NAFLD was diagnosed from abdominal ultrasonography results. The association between quartiles of fruit or vegetable consumption and NAFLD prevalence was assessed using logistic regression analysis, with lowest category as reference.

RESULTS

The prevalence of NAFLD was 34.9% in men and 11.7% in women. Adjusted for age and lifestyle factors, fruit intake was inversely associated with NAFLD in both sexes. However, these associations disappeared after further adjustment for body mass index. Consumption of total vegetables was not associated with NAFLD. In women, a linear inverse association was demonstrated between green and yellow vegetable intake and NAFLD in the final model (P_trend = 0.04), but odds ratios for any intake category did not reach significance.

CONCLUSIONS

No obesity-independent association was found between fruit or vegetable intake and NAFLD. According to the findings of this study, Japanese do not need to restrict fruit consumption to limit fructose intake as a means of preventing NAFLD.

Applicability of a Web-Based, Individualized Exercise Intervention in Patients With Liver Disease, Cystic Fibrosis, Esophageal Cancer, and Psychiatric Disorders: Process Evaluation of 4 Ongoing Clinical Trials

Background

In the primary and secondary prevention of civilization diseases, regular physical activity is recommended in international guidelines to improve disease-related symptoms, delay the progression of the disease, or to enhance postoperative outcomes. In the preoperative context, there has been a paradigm shift in favor of using preconditioning concepts before surgery. Web-based interventions seem an innovative and effective tool for delivering general information, individualized exercise recommendations, and peer support.

Objective

Our first objective was to assess feasibility of our Web-based interventional concept and analyze similarities and differences in a sustained exercise implementation in different diseases. The second objective was to investigate the overall participants’ satisfaction with our Web-based concept.

Methods

A total of 4 clinical trials are still being carried out, including patients with esophageal carcinoma scheduled for oncologic esophagectomy (internet-based perioperative exercise program, iPEP, study), nonalcoholic fatty liver disease (hepatic inflammation and physical performance in patients with nonalcoholic steatohepatitis, HELP, study), depression (exercise for depression, EXDEP, study), and cystic fibrosis (cystic fibrosis online mentoring for microbiome, exercise, and diet, COMMED, study). During the intervention period, the study population had access to the website with disease-specific content and a disease-specific discussion forum. All participants received weekly, individual tailored exercise recommendations from the sports therapist. The main outcome was the using behavior, which was obtained by investigating the log-in rate and duration.

Results

A total of 20 participants (5 from each trial) were analyzed. During the intervention period, a regular contact and a consequent implementation of exercise prescription were easily achieved in all substudies. Across the 4 substudies, there was a significant decrease in log-in rates (P<.001) and log-in durations (P<.001) over time. A detailed view of the different studies shows a significant decrease in log-in rates and log-in durations in the HELP study (P=.004; P=.002) and iPEP study (P=.02; P=.001), whereas the EXDEP study (P=.58; P=.38) and COMMED study (P=.87; P=.56) showed no significant change over the 8-week intervention period. There was no significant change in physical activity within all studies (P=.31). Only in the HELP study, the physical activity level increased steadily over the period analyzed (P=.045). Overall, 17 participants (85%, 17/20) felt secure and were not scared of injury, with no major differences in the subtrials.

Conclusions

The universal use of the Web-based intervention appears to be applicable across the heterogonous collectives of our study patients with regard to age and disease. Although the development of physical activity shows only moderate improvements, flexible communication and tailored support could be easily integrated into patients’ daily routine.

Trial Registration

iPEP study: ClinicalTrials.gov NCT02478996; https://clinicaltrials.gov/ct2/show/NCT02478996 (Archived by WebCite at http://www.webcitation.org/6zL1UmHaW); HELP study: ClinicalTrials.gov NCT02526732; http://www.webcitation.org/6zJjX7d6K (Archived by WebCite at http://www.webcitation.org/6Nch4ldcL); EXDEP study: ClinicalTrials.gov NCT02874833; https://clinicaltrials.gov/ct2/show/NCT02874833 (Archived by WebCite at http://www.webcitation.org/6zJjj7FuA)

Association between physical activity and risk of nonalcoholic fatty liver disease: a meta-analysis

BACKGROUND

Increased physical activity (PA) is a key element in the management of patients with nonalcoholic fatty liver disease (NAFLD); however, its association with NAFLD risk has not been systematically assessed. This meta-analysis of observational studies was to quantify this association with dose-response analysis.

METHODS

Electronic databases were searched to January 2017 for studies of adults reporting the risk of NAFLD in relation to PA with cohort or case-control designs. Studies that reported sex-specific data were included as separate studies. The overall risk estimates were pooled using a random-effects model, and the dose-response analysis was conducted to shape the quantitative relationship.

RESULTS

A total of 6 cohort studies from 5 articles with 32,657 incident NAFLD cases from 142,781 participants, and 4 case-control studies from 3 articles with 382 NAFLD cases and 302 controls were included. Compared with the lowest PA level, the highest PA level was associated with a risk reduction of NAFLD in cohort [RR (risk ratio) 0.79, 95% CI (confidence interval) 0.71-0.89] and case-control studies [OR (odds ratio) 0.43, 95% CI 0.27-0.68]. For cohort studies, both highest and moderate PA levels were superior to the light one in lowering NAFLD risk (p_{for interaction} = 0.006 and 0.02, respectively), and there was a log-linear dose-response association (p_{for nonlinearity} = 0.10) between PA and NAFLD risk [RR 0.82 (95% CI 0.73-0.91) for every 500 metabolic equivalent (MET)-minutes/week increment in PA].

CONCLUSIONS

Increased PA may lead to a reduced risk of NAFLD in a dose-dependent manner, and the current guideline-recommended minimum PA level that approximates to 500 MET-minutes/week is able to moderately reduce the NAFLD risk.

Nonalcoholic fatty liver disease in Asia: emerging perspectives

As in the West, nonalcoholic fatty liver disease (NAFLD) is the commonest chronic liver disease in Asia, with a prevalence higher than 40 % in some countries. The risk factors for NAFLD development are similar to those in Western countries, including increased body mass index, diabetes, insulin resistance, and metabolic syndrome. NAFLD in Asians is associated with different extrahepatic manifestations involving the cardiovascular, gastrointestinal, and renal systems. A considerable proportion of Asians with NAFLD are described as having "lean" NAFLD. Present in approximately 20 % of the Asian population, lean NAFLD is closely linked with insulin resistance, diabetes, and other metabolic complications, but its association with disease progression to nonalcoholic steatohepatitis and cirrhosis remains to be defined. There is emerging evidence of the interactions of NAFLD with hepatitis B virus and hepatitis C virus infection in Asia. Unlike in Western countries, NAFLD constitutes only a minority of cirrhosis and hepatocellular carcinoma cases in Asia. Possible explanations are the lower prevalence of obesity and the overwhelming problem of viral hepatitis in Asia. With aging of the obesity cohort in Asia, NAFLD-related liver complications are expected to increase.

Advances in research of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) has become the most common liver disease worldwide. It is related with increased morbidity and mortality of cirrhosis and hepatocellular carcinoma (HCC); however, its main health implications are increased risks of developing type 2 diabetes (T2D), cardiovascular diseases and malignancies. This paper reviews the advances in research of NAFLD in terms of epidemiology, risk factors, assessment of disease progression and risks for combined cardiovascular diseases and/or T2D as well as management.

Short sleep duration reduces the risk of nonalcoholic fatty liver disease onset in men: a community-based longitudinal cohort study

BACKGROUND

Epidemiologic studies show an association between short sleep duration and the presence of nonalcoholic fatty liver disease (NAFLD). This study examined the association between short sleep duration and the onset of NAFLD.

METHODS

This community-based, retrospective, longitudinal cohort study included 6,370 Japanese subjects who had undergone annual health check-ups more than twice at a single center between April 2003 and March 2010. After excluding 3,941 subjects, the records of 2,429 Japanese subjects were reviewed.

RESULTS

Two groups comprised the study cohort: those with short (≤ 6 h) sleep durations (n = 1,543) and those with moderate (7-8 h) sleep durations (n = 886). During the observation period, 296 subjects developed NAFLD. Multivariate analysis identified an association between short sleep duration and the reduced onset of NAFLD in men (odds ratio: 0.551, 95% confidence interval 0.365-0.832, p = 0.005). There was no association between short sleep duration and NAFLD onset in women. The prevalence of NAFLD onset in men increased significantly as sleep duration increased, as follows: 12.5, 18.4, and 27.4% among subjects who had sleep durations of ≤ 4, 5-6, and 7-8 h, respectively (p = 0.02).

CONCLUSIONS

This study demonstrates an association between sleep duration and NAFLD onset. Short sleep duration reduced the risk of NAFLD onset in men. Correct recognition is important to prevent disease progression and further complications.

Oxidative stress in obesity: a critical component in human diseases

Obesity, a social problem worldwide, is characterized by an increase in body weight that results in excessive fat accumulation. Obesity is a major cause of morbidity and mortality and leads to several diseases, including metabolic syndrome, diabetes mellitus, cardiovascular, fatty liver diseases, and cancer. Growing evidence allows us to understand the critical role of adipose tissue in controlling the physic-pathological mechanisms of obesity and related comorbidities. Recently, adipose tissue, especially in the visceral compartment, has been considered not only as a simple energy depository tissue, but also as an active endocrine organ releasing a variety of biologically active molecules known as adipocytokines or adipokines. Based on the complex interplay between adipokines, obesity is also characterized by chronic low grade inflammation with permanently increased oxidative stress (OS). Over-expression of oxidative stress damages cellular structures together with under-production of anti-oxidant mechanisms, leading to the development of obesity-related complications. The aim of this review is to summarize what is known in the relationship between OS in obesity and obesity-related diseases.