Association between dietary sodium intake and non-alcoholic fatty liver disease in the US population

Sex-Specific Association between Sodium Intake Estimated by 24-Hour Urinary Sodium Excretion and Nonalcoholic Fatty Liver Disease: The Community-Based Prospective Cohort Study

Evidence for the association between high sodium intake and the onset of nonalcoholic fatty liver disease (NAFLD) is insufficient. This study examined the sex-specific association between sodium intake and the risk of NAFLD. This study included 2582 adults (aged 40-69 years; 1011 males and 1571 females). The total sodium excreted over 24 h was estimated from spot urine specimens using Tanaka's equation. Based on these estimates, participants were categorized into three groups according to their 24-h urinary sodium excretion levels: lowest (T1), middle (T2), and highest (T3). In addition, the participants were divided into non-NAFLD (≤36) and NAFLD (>36) groups based on the hepatic steatosis index. During the follow-up period (14 years), NAFLD was observed in 551 participants. The estimated 24-h urinary sodium excretion levels were positively associated with the incidence of NAFLD in all subjects. Upon sex stratification, females in the T2 and T3 groups exhibited adjusted hazard ratios of 1.35 and 1.51, respectively, compared with the T1 group. However, a significant relationship was not observed in males. High intake of sodium, especially among females, may be an important factor contributing to the development of NAFLD. Individuals with high sodium intake should be appropriately counselled and monitored for the risk of NAFLD.

Hepatic Transcriptomics Reveals Reduced Lipogenesis in High-Salt Diet Mice

It has been demonstrated that a high salt diet (HSD) increases the risk of cardiovascular disease and metabolic dysfunction. In particular, the impact and molecular mechanisms of long-term HSD on hepatic metabolism remain largely unknown. To identify differentially expressed genes (DEGs) affecting the metabolism of liver tissues from HSD and control groups, a transcriptome analysis of liver tissues was performed in this study. As a result of the transcriptome analysis, the expression of genes related to lipid and steroid biosynthesis (such as Fasn, Scd1, and Cyp7a1) was significantly reduced in the livers of HSD mice. Additionally, several gene ontology (GO) terms have been identified as associated with metabolic processes in the liver, including the lipid metabolic process (GO: 0006629) and the steroid metabolic process (GO: 0008202). An additional quantitative RT-qPCR analysis was conducted to confirm six down-regulated genes and two up-regulated genes. Our findings provide a theoretical basis for further investigation of HSD-induced metabolic disorders.

Dietary Sodium and Nonalcoholic Fatty Liver Disease: A Systematic Review

(1) Introduction: Restriction in sodium intake is an important strategy for reducing cardiovascular morbidity and mortality, considering the direct influence of high-sodium diet consumption on the development of hypertension and cardiovascular diseases. There are only a few studies dealing with the influence of dietary sodium on the development of nonalcoholic fatty liver disease (NAFLD). In this systematic review, evidence in humans and animal models was compiled in a critical view of the influence of dietary sodium intake patterns on NAFLD markers; (2) Methods: Systematic review of PubMed data. Clinical outcomes included the prevalence/incidence of NAFLD for human studies, and NAFLD markers (hepatic lipogenesis, and markers of steatosis, fibrosis, and inflammation) for animal studies. The protocol was registered at the International Prospective Register of Systematic Review (PROSPERO; CRD42023390447); (3) Results and Conclusion: Seven studies in humans and eight in animals were included. All studies in humans were observational and associated high-sodium intake with NAFLD. However, in animals, both the increased and reduced consumption of sodium negatively influenced markers of liver steatosis, inflammation, and fibrosis.

Is elevated ALT associated with lifestyle risk factors? A population-based survey

Purpose

Given the high prevalence of non-alcoholic fatty liver disease (NAFLD) and the role of Alanine aminotransferase (ALT) in diagnosing liver injury along with the increasing prevalence of lifestyle risk factors, we aimed to evaluate the association between serum ALT level and lifestyle risk factors in a population-based survey.

Methods

This was a population-based study conducted in rural and urban areas of Iran in 2016. Cluster sampling method was applied to enroll a total of 31,050 participants aged ≥ 18. Demographic data, anthropometric measures, and laboratory samples were gathered. Multivariate logistic regression analyses were performed using three different cut-off levels for elevated ALT to assess the relationship between elevated ALT and lifestyle risk factors.

Results

The prevalence of elevated ALT was significantly higher in men with elevated body mass index (BMI), waist-to-hip ratio (WTH), hip circumference, and salt consumption, likewise, in women with higher BMI and WTH. In the multivariate logistic model adjusted for age and sex, high WTH (adjusted odds ratio: 1.73; 95% CI 1.52-1.96), BMI > 25 (1.51; 95% CI 1.29-1.76), hip circumference (1.26; 95% CI 1-1.58), and current smoking (0.67; 95% CI 0.56-0.8) were associated with elevated ALT levels using American cut-off (ALT > 33U/L for male and ALT > 25U/L for female). Only physical measurements (BMI, WTH) but not lifestyle risk factors were related to the increased ALT regardless of the selected cut-offs.

Conclusion

As elevated ALT was associated with several lifestyle risk factors, stewardship programs should be established to modify lifestyle risk factors, such as abdominal obesity and physical inactivity.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40200-022-01137-6.

Potential role of inflammation in relation to dietary sodium and β-carotene with non-alcoholic fatty liver disease: a mediation analysis

Background

High sodium intake has been linked to the prevalence of non-alcoholic fatty liver disease (NAFLD), but underlying mechanism remains unclear. This study aims to explore the role of chronic inflammation in the association between sodium and NAFLD. We also observed whether β-carotene, which had a strong anti-inflammatory effect, lowers the odds of NAFLD.

Methods

We performed mediation analyses to assess the mediating effects of C-reactive protein (CRP) and red cell distribution width (RDW) on the relationship between dietary sodium and NAFLD defined by the hepatic steatosis index (HSI) and the fatty liver index (FLI), respectively.

Results

A total of 6725 participants were included in this study. Compared with the high sodium-low carotene group, participants in the high sodium-high carotene group had 16% and 26% lower odds for HSI and FLI-defined NAFLD, respectively. There were positive indirect effects of dietary sodium intake on the HSI-defined NAFLD (indirect effect: 0.0057, 95% CI: 0.0021–0.0091, P < 0.0001), as well as the FLI defined NAFLD (indirect effect: 0.0081, 95% CI: 0.0024–0.0162, P < 0.0001) when C-reactive protein (CRP) was considered as a mediator. The mediating effects were somewhat attenuated after further adjusting for dietary β-carotene intake. Similar results were found when RDW was considered as a mediator in the HSI-defined NAFLD analysis.

Conclusions

Higher sodium intake increases the odds of NAFLD by upregulating inflammation. Dietary β-carotene may attenuate this association by down regulating inflammation.

Role of high-salt diet in non-alcoholic fatty liver disease: a mini-review of the evidence

With the rising incidence of both obesity and diabetes, non-alcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease worldwide. However, lifestyle intervention remains to be an effective approach for NAFLD due to lack of therapeutic medication. Recently, salt, an essential micronutrient free of calories, has raised a global concern owing to its wide-range healthy relevance. Accumulated evidence has suggested that a long-term high-salt diet (HSD) independently increases the risk of NAFLD. In the past decades, a number of studies have been reported regarding the mechanism of much investigation concerning HSD-induced NAFLD. Here, we review the updates in epidemiology and molecular mechanism of HSD-induced NAFLD and provide a novel insight into the role of HSD in the regulation of lipid metabolism.

Nonalcoholic Fatty Liver Disease and Cardiovascular Disease: a Review of Shared Cardiometabolic Risk Factors

The prevalence of nonalcoholic fatty liver disease (NAFLD) is rising. NAFLD/nonalcoholic steatohepatitis (NASH) is associated not only with hepatic morbidity and mortality but also with an increased cardiovascular risk. NAFLD and cardiovascular disease (CVD) share several risk factors, such as obesity, metabolic syndrome, hypertension, dyslipidemia, type 2 diabetes, and chronic kidney disease. This review summarizes the evidence linking cardiometabolic risk factors and NAFLD in the context of risk for CVD. The cause of NAFLD/NASH is complex, involving a range of factors from genetics to lifestyle and energy balance. Genetically driven high liver fat content does not appear to be causally associated with increased CVD risk. In contrast, metabolic dysfunction not only predisposes to liver pathology but also leads to a significantly higher CVD risk. Given that NAFLD pathophysiology is influenced by multiple factors, each patient is unique as to their risk of developing CVD and liver pathology. At the same time, the rising burden of NAFLD/NASH is closely linked with the global increase in metabolic disorders, including obesity and type 2 diabetes. Therefore, both personalized therapeutic approaches that recognize individual pathophysiology, as well as public health policies that address the root causes of cardiometabolic risk factors for NAFLD may be needed to effectively address the NAFLD/NASH epidemic.

Sodium in relation with nonalcoholic fatty liver disease: A systematic review and meta-analysis of observational studies

Findings on the association of sodium with nonalcoholic fatty liver disease (NAFLD) are conflicting. The present systematic review and meta‐analysis study aimed to assess the association between salt or sodium intake or serum sodium levels and NAFLD risk. Relevant articles were identified by searching PubMed, Web of Knowledge, Scopus, Proquest, and Embase databases through May 1, 2021, without language restriction. The pooled odds ratio (OR) and 95% confidence interval (CI) were estimated using Der‐Simonian and Laird method and random‐effects meta‐analysis. The certainty of the evidence was rated using the GRADE method. Out of 6470 documents, 7 epidemiological/observational (1 cohort, 1 case–control, and 5 cross‐sectional) studies on the relationship between dietary salt/sodium intakes and NAFLD risk met our inclusion criteria. The meta‐analysis of all studies showed a significant positive association between the highest salt/sodium intake and NALFD risk (OR = 1.60, 95% CI: 1.19–2.15) with a meaningful heterogeneity among studies (I² = 96.70%, p‐value <.001). The NAFLD risk was greater in the studies with higher quality (OR = 1.81, 95% CI: 1.24–2.65) or using the equation‐based methods for NAFLD ascertainment (OR = 2.02, 95% CI: 1.29–3.17) or urinary sodium collection as a sodium intake assessment (OR = 2.48, 95% CI: 1.52–4.06). The overall certainty of the evidence was very low. In conclusion, high sodium intake seems to be related to increased NAFLD risk. Further well‐designed studies are needed to clarify this association and shed light on the underlying mechanisms.

Transcriptome Analysis of Multiple Metabolic Tissues in High-Salt Diet-Fed Mice

High-salt diet (HSD) is associated with dysregulated metabolism and metabolic disorders. Although previous studies have indicated its effect on metabolic tissues, the involving molecular mechanisms are not quite understood. In the present study, we provided a comprehensive transcriptome analysis on multiple metabolic tissues of HSD-fed mouse model by RNA sequencing. We observed that several genes associated with de novo lipogenesis and cholesterol biosynthesis were significantly downregulated in white adipose tissue and liver tissue of HSD mice group, such as Fasn, Scd1, Acaca, and Thrsp. Furthermore, combined with secretome datasets, our results further demonstrated that HSD could alter expression levels of organokines in metabolic tissues, for example, Tsk and Manf, in liver tissue and, thus, possibly mediate cross-talk between different metabolic tissues. Our study provided new insight about molecular signatures of HSD on multiple metabolic tissues.

Association between healthy eating index-2015 and various cognitive domains in US adults aged 60 years or older: the National Health and Nutrition Examination Survey (NHANES) 2011-2014

BACKGROUND

Diet, as a modifiable factor, plays an important role in cognitive function. However, the association between adherence to the 2015-2020 Dietary Guidelines for Americans (DGA), measured by Healthy Eating Index (HEI)-2015, and cognitive function remains unclear. This study aims to explore whether HEI-2015 is associated with various cognitive domains and whether such association is modified by age, gender, or ethnicity in the US adults aged 60 years or older using data from the National Health and Nutrition Examination Survey (NHANES) 2011-2014.

METHODS

HEI-2015 scores were calculated from 24-h dietary recall interviews. Cognitive function was evaluated by Digit Symbol Substitution Test (DSST, a measure of processing speed), Animal Fluency Test (AFT, a measure of executive function), a subtest from Consortium to Establish a Registry for Alzheimer's disease (CERAD, a measure of memory), and a composite-z score calculated by summing z scores of individual tests. The associations between HEI-2015 scores and cognitive performance were explored using multiple linear regression models.

RESULTS

A total of 2450 participants aged 60 years or older were included. Participants with higher HEI-2015 scores were more likely to have higher DSST, AFT as well as composite-z scores (P<0.05). Significant interaction effects were identified between HEI-2015 and ethnicity in specific cognitive domains (P_interaction<0.05). Among HEI-2015 components, higher intakes of whole fruits and seafood and plant protein were associated with better cognitive performance (P<0.05).

CONCLUSION

Higher adherence to DGA is associated with better cognitive performance, especially regarding processing speed and executive function among the US adults aged 60 years or older.