Intake of n-3 polyunsaturated fatty acids and non-alcoholic fatty liver disease: a cross-sectional study in Japanese men and women

Circulating fatty acids and risk of severe non-alcoholic fatty liver disease in the UK biobank: a prospective cohort of 116 223 individuals

Fatty acid (FA) metabolism plays an important role in the development of nonalcoholic fatty liver disease (NAFLD). However, data on the relationship between circulating FAs and NAFLD risk are limited. This study aims to assess the associations between specific circulating FAs and severe NAFLD risk among the general population. Overall 116 223 participants without NAFLD and other liver diseases from the UK Biobank were enrolled between 2006 and 2010 and were followed up until the end of 2021. Plasma concentrations of saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs), and polyunsaturated fatty acids (PUFAs) were analyzed using an NMR-based biomarker profiling platform. Hazard ratios (HRs) and 95% confidence intervals (CIs) of NAFLD risk were estimated using Cox proportional-hazard models adjusted for other potential confounders. During a mean follow-up of 12.3 years, we documented 1394 cases of severe NAFLD. After multivariate adjustment, plasma SFAs and MUFAs were associated with a higher risk of severe NAFLD, whereas plasma n-3 PUFAs, n-6 PUFAs, and linoleic acid (LA) were associated with a lower risk. As compared with the lowest quartile, HRs (95% CIs) of severe NAFLD risk in the highest quartiles were 1.85 (1.45-2.36) for SFAs, 1.74 (1.23-2.44) for MUFAs, 0.79 (0.65-0.97) for n-3 PUFAs, 0.68 (0.48-0.96) for n-6 PUFAs, and 0.73 (0.54-0.99) for LA. The significant relationships were mainly mediated by serum TG for SFAs, HDL-C for MUFAs and n-6 PUFAs, and C-reactive protein for n-3 PUFAs. Plasma SFAs were associated with a more pronounced increase in the risk of severe NAFLD among participants with fewer SFA-associated alleles (P interaction = 0.032). Dietary recommendations for reducing plasma SFAs and MUFAs while increasing n-3 and n-6 PUFAs may be protective for severe NAFLD, which could be mediated by lipid metabolism and inflammation.

Biosynthetic deficiency of docosahexaenoic acid causes nonalcoholic fatty liver disease and ferroptosis-mediated hepatocyte injury

Exogenous omega-3 fatty acids, particularly docosahexaenoic acid (DHA), have shown to exert beneficial effects on nonalcoholic fatty liver disease (NAFLD), which is characterized by the excessive accumulation of lipids and chronic injury in the liver. However, the effect of endogenous DHA biosynthesis on the lipid homeostasis of liver is poorly understood. In this study, we used a DHA biosynthesis-deficient zebrafish model, elovl2 mutant, to explore the effect of endogenously biosynthesized DHA on hepatic lipid homeostasis. We found the pathways of lipogenesis and lipid uptake were strongly activated, while the pathways of lipid oxidation and lipid transport were inhibited in the liver of elovl2 mutants, leading to lipid droplet accumulation in the mutant hepatocytes and NAFLD. Furthermore, the elovl2 mutant hepatocytes exhibited disrupted mitochondrial structure and function, activated endoplasmic reticulum stress, and hepatic injury. We further unveiled that the hepatic cell death and injury was mainly mediated by ferroptosis, rather than apoptosis, in elovl2 mutants. Elevating DHA content in elovl2 mutants, either by the introduction of an omega-3 desaturase (fat1) transgene or by feeding with a DHA-rich diet, could strongly alleviate NAFLD features and ferroptosis-mediated hepatic injury. Together, our study elucidates the essential role of endogenous DHA biosynthesis in maintaining hepatic lipid homeostasis and liver health, highlighting that DHA deficiency can lead to NAFLD and ferroptosis-mediated hepatic injury.

Trends in Oxidative Balance Score and Prevalence of Metabolic Dysfunction-Associated Steatotic Liver Disease in the United States: National Health and Nutrition Examination Survey 2001 to 2018

BACKGROUND

Most studies have primarily focused on assessing the association between diet or exercise patterns and metabolic dysfunction-associated steatotic liver disease (MASLD). This study adopted a more comprehensive approach by introducing the oxidative balance score (OBS) to evaluate the combined effects of diet and lifestyle on the body's antioxidant ability. Our main objective was to investigate the association between OBS and the burden of MASLD in the United States.

METHODS

Participants with complete information from 2001 to 2018 were included. In the absence of other definite liver injury factors, the United States fatty liver index (us-FLI) ≥ 30 was used as the diagnostic criterion for MASLD. We first calculated the weighted prevalence for each cycle and stratified it according to demographic and metabolic-related disease characteristics. Subsequently, weighted multiple logistic regression was used to evaluate the relationship between OBS and MASLD. In addition, we explored the body's inflammatory state and the level of insulin resistance (IR) in mediating OBS and MASLD.

RESULTS

From 2001 to 2018, the prevalence of MASLD in the U.S. population as a whole increased from 29.76% to 36.04%, and the rate was higher in people with metabolic-related diseases. Notably, OBS exhibited a negative correlation with MASLD. Participants in the highest tertile of OBS had a significantly lower prevalence of MASLD compared to those in the lowest tertile [OR: 0.72, 95%CI: (0.57, 0.92), p < 0.001]. Moreover, a high OBS is associated with a lower inflammatory state and level of IR. The body's inflammatory state and IR level mediated the association between OBS and MASLD by 5.2% and 39.7%, respectively (both p < 0.001).

CONCLUSIONS

In this study, we observed an increasing prevalence of MASLD over the years. A higher OBS was associated with a lower risk of MASLD, especially when OBS ≥ 25. The body's inflammatory state and IR level mediate the association between OBS and MASLD, but the mechanism needs to be further investigated.

Oxidative balance score is inversely associated with the incidence of non-alcoholic fatty liver disease

BACKGROUND & AIMS

The contribution of the balance between overall oxidative stress and antioxidant status in non-alcoholic fatty liver disease (NAFLD) is unclear. The oxidative balance score (OBS) comprises dietary and lifestyle pro- and antioxidant components that indicate the overall oxidative stress burden. We investigated the association between OBS and the incidence of NAFLD in middle-aged and older Korean adults.

METHODS

Among the 10,030 participants of the Korean Genome and Epidemiology Study_Ansan and Ansung cohort, 5065 without NAFLD at baseline were selected for secondary analysis. OBS was categorized into quartiles. Multiple Cox proportional hazard regression analyses were performed to estimate the hazard ratio (HR) and 95% confidence interval (CI) for NAFLD incidence by sex-specific OBS quartile groups after adjusting for confounders.

RESULTS

During the follow-up period (median 13.4 years), 913 (43.2%) men and 1288 (43.9%) women were newly diagnosed with NAFLD. Compared with that of the lowest quartile (Q1) group, the adjusted HR (95% CI) for NAFLD incidence in Q2, Q3, and Q4 groups was 0.85 (0.71-1.00), 0.65 (0.54-0.78), and 0.50 (0.40-0.62) in men, and 0.85 (0.73-0.99), 0.66 (0.56-0.77), and 0.48 (0.40-0.59) in women, respectively, and for NAFLD incidence, per incremental change in OBS, was 0.90 (0.87-0.92) in men and 0.88 (0.86-0.90) in women.

CONCLUSIONS

A higher OBS was significantly associated with a lower risk for NAFLD incidence. Maintaining a healthy lifestyle and an antioxidant-rich diet is a potentially viable strategy for preventing NAFLD.

Effects of oily fish and its fatty acid intake on non-alcoholic fatty liver disease development among South Korean adults

Background

The benefits of fish fatty acid intake for non-alcoholic fatty liver disease (NAFLD) are rarely reported, although a previous study assessed the relationship between oily fish consumption and the prevalence of NAFLD.

Aims

We investigated whether oily fish and fish-based monounsaturated fatty acids, polyunsaturated fatty acids, and omega-3 fatty acids affect the development of NAFLD in South Korean adults.

Methods

In this large-scale cohort study, 44,139 participants of the Health Examinees study were selected for analysis after 5 years of follow-up. NAFLD is diagnosed with a non-invasive index, the fatty liver index. Using multivariable Cox proportional hazards models, adjusted for age, body mass index, total energy intake, education, physical activity, smoking status, and drinking (alcohol) status, we calculated the hazard ratios and 95% confidence intervals.

Results

For men, NAFLD had no statistically significant associations with quartiles of total oily fish or its fatty acid intake. However, among women, an inverse association was observed (all p for trend <0.05). Regarding the standard deviation (SD) increment of total oily fish or its fatty acid intake by one, all fatty acids from oily fish showed inverse associations for NAFLD in both men and women. After stratified analyses, we found that drinking status and menopause status were independent risk factors for NAFLD. Oily fish or its fatty acid intake has the same benefit pattern on metabolic dysfunction-associated fatty liver disease as NAFLD.

Conclusion

Oily fish and its fatty acid intake showed a preventative benefit for NAFLD and metabolic dysfunction-associated fatty liver disease, especially in South Korean women.

Effects of Dietary α-Linolenic Acid Treatment and the Efficiency of Its Conversion to Eicosapentaenoic and Docosahexaenoic Acids in Obesity and Related Diseases

The essential fatty acid alpha-linolenic acid (ALA) is present in high amounts in oils such as flaxseed, soy, hemp, rapeseed, chia, and perilla, while stearidonic acid is abundant in echium oil. ALA is metabolized to eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) by desaturases and elongases in humans. The conversion of ALA to EPA and DHA is limited, and these long-chain n−3 polyunsaturated fatty acids (PUFAs) are mainly provided from dietary sources (fish and seafood). This review provides an overview of studies that explored the effects of dietary supplementation with ALA in obesity and related diseases. The obesity-associated changes of desaturase and elongase activities are summarized, as they could influence the metabolic conversion of ALA. Generally, supplementation with ALA or ALA-rich oils leads to an increase in EPA levels and has no effect on DHA or omega-3 index. According to the literature data, stearidonic acid could enhance conversion of ALA to long-chain n−3 PUFA in obesity. Recent studies confirm that EPA and DHA intake should be considered as a primary dietary treatment strategy for improving the omega-3 index in obesity and related diseases.

Systematic Review and Meta-analysis: The Role of Diet in the Development of Nonalcoholic Fatty Liver Disease

BACKGROUND & AIMS

The association of nonalcoholic fatty liver disease (NAFLD) with dietary factors is well established but not thoroughly investigated. This systematic review and meta-analysis synthesizes available evidence regarding the effect of nutrition on the presence and severity of NAFLD.

METHODS

A literature search was conducted identifying studies published between January 1985 and May 2021. We included studies with a dietary assessment and anthropometry based on validated tools, performed by a qualified dietitian or a trained health professional. We examined differences between patients with NAFLD and healthy controls as well as patients with NAFLD and nonalcoholic steatohepatitis (NASH). Risk of bias was assessed with the Risk Of Bias In Non-randomised Studies of Interventions (ROBINS-I) tool.

RESULTS

There were 60 eligible studies with 100,621 patients. The risk of bias was moderate for the majority of studies (41/60; 68%). According to meta-analyses, total caloric intake was higher in patients with NAFLD compared with controls (mean difference, 78.08; 95% confidence interval, 41.03-115.13). Macronutrient (protein, fat, and carbohydrate) consumption as proportion of total caloric intake and daily intake of fiber, caffeine and vitamins E, A, and C did not significantly differ between patients with NAFLD and controls. Soft drink consumption had a trend towards association with the presence of NAFLD. However, the odds ratio was 4.4 and the confidence intervals very wide. Finally, there was no significant difference in any comparison between patients with NAFLD and NASH, although the number of patients was relatively small. All meta-analyses had significant heterogeneity.

CONCLUSIONS

Overall, despite high heterogeneity among studies, this meta-analysis demonstrated that higher caloric intake is positively associated with NAFLD, whereas diet composition in macronutrients was not associated with the presence or severity of the disease.

Evaluation of energy intake by brief-type self-administered diet history questionnaire among male patients with stable/at risk for chronic obstructive pulmonary disease

Background and objective

Weight loss and reduced fat-free mass are independent risk factors for mortality among patients with chronic obstructive pulmonary disease (COPD). These factors are important for determining diet therapy and examining the validity of assessment for energy intake (EI). We assessed the agreement of EI between a brief-type self-administered diet history questionnaire (BDHQ) and the doubly labelled water (DLW) method among male patients with stable/at risk for COPD.

Method

In this cross-sectional observational study, data for 33 male patients were analysed. At the first visit, EI was estimated using a BDHQ (EI_BDHQ). Total energy expenditure (TEE) was measured during 13–15 days by the DLW method, while corrected EI was calculated using the TEE and weight change during the DLW period (EI_DLW). The difference between EI_BDHQ and EI_DLW was evaluated by the Bland-Altman method. Multiple regression analysis was used to determine the proportion of variance in the difference between EI_BDHQ and EI_DLW, as determined by the patient’s characteristics.

Results

EI_BDHQ was 2100 (95% CI: 1905 to 2295) kcal/day in the total population. A fixed bias was observed between EI_BDHQ and EI_DLW as −186 (95% CI: −422 to 50) kcal/day, while a proportional bias was not detected by the Bland-Altman analysis. Age, weight, anxiety and interleukin 6 were responsible for 61.7% of the variance in the difference between both EIs in a multiple regression model.

Conclusions

The BDHQ underestimated EI among male patients with stable/at risk for COPD, but this estimation error was within an acceptable range compared with previous studies. EI_BDHQ precision might be improved by considering common COPD traits, including inflammatory condition and mental state.

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

BACKGROUND

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

METHODS

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

RESULT

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

CONCLUSION

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

Gender Difference on the Effect of Omega-3 Polyunsaturated Fatty Acids on Acetaminophen-Induced Acute Liver Failure

Acetaminophen (APAP) toxicity is the leading cause of drug-induced liver failure, which is closely related to mitochondrial dysfunction and oxidative damage. Studies in clinical trials and in animal models have shown that omega-3 polyunsaturated fatty acids (n-3 PUFAs) affect the progression of various types of liver damage. Interestingly, the sex-dependent effect of n-3 PUFAs on human health has also been well documented. However, it is unknown whether supplementation of n-3 PUFAs modulates the pathogenesis of APAP-induced liver failure with sex-specificity. Our results showed that both endogenous and exogenous n-3 PUFAs significantly aggravated the APAP-induced liver injury in male mice, whereas the opposite effects were observed in females. In vivo and in vitro studies demonstrated that estrogen contributes to the gender difference in the regulation of n-3 PUFAs on APAP overdose. We found that n-3 PUFA-mediated regulation of hepatic oxidative stress response and autophagy upon APAP challenge is distinct between male and female mice. Moreover, we provided evidence that β-catenin signaling activation is responsible for the sex-dependent regulation of APAP hepatotoxicity by n-3 PUFAs. Together, these findings indicated that supplementation with n-3 PUFAs displays sex-differential effect on APAP hepatotoxicity and could have profound significance in the clinical management for drug-induced liver injury.

Association of alcohol consumption with prevalence of fatty liver after adjustment for dietary patterns: Cross-sectional analysis of Japanese middle-aged adults

Background & aims

Moderate alcohol intake is associated with reduced prevalence or incidence of fatty liver. However, whether or not the association is independent of dietary patterns remains unclear. We aimed to evaluate the cross-sectional association of alcohol intake with fatty liver after accounting for dietary patterns and obesity.

Methods

We assessed 4579 adults aged 30–79 years who participated in routine clinical examinations in St. Luke's International Hospital, Japan (January to March, 2015). We assessed their habitual diet using diet-history questionnaire, estimated alcohol intake, and derived dietary pattern variables using factor analysis. Fatty liver was ascertained using ultrasonography. Linear and U-shaped associations of alcohol intake with fatty liver were evaluated using Poisson regression, and a post hoc analysis was conducted after detecting potential outliers for alcohol intake and excluding them using sex-specific statistics (median plus 2 × interquartile range).

Results

Fatty liver was ascertained in 1120 participants (24.5%). Whereas no significant association of alcohol intake with fatty liver was observed when potential outliers of alcohol intake were included (p = 0.25), a significant U-shaped association was observed after excluding the outliers with and without adjustment for dietary patterns (p = 0.003 and 0.02, respectively). The lowest prevalence was estimated when alcohol consumption was approximately 7% of energy, with a prevalence ratio of 0.72 (95% confidence interval = 0.59–0.86) compared to non-drinkers. The association became imprecise and attenuated toward the null after further adjustment for body mass index (p = 0.06).

Conclusions

Alcohol intake showed a U-shaped association with fatty liver prevalence. This association was independent of underlying dietary patterns, while it was sensitive to excessive alcohol intake and obesity status, providing clinical implications for the prevention of fatty liver.

Erythrocyte membrane n-3 polyunsaturated fatty acids are inversely associated with the presence and progression of nonalcoholic fatty liver disease in Chinese adults: a prospective study

PURPOSE

Previous studies have shown that high-dose supplementation with n-3 polyunsaturated fatty acids (PUFAs) may benefit patients with nonalcoholic fatty liver disease (NAFLD), but the association of n-3 PUFAs with NAFLD among individuals with normal diets is only speculative. We investigated the cross-sectional and prospective associations between n-3 PUFAs and NAFLD in Chinese adults.

METHODS

This community-based prospective study included 3049 men and women (40-75 years) in Guangzhou, China, whose participants completed an NAFLD ultrasound evaluation and erythrocyte PUFA tests. A total of 2660 participants underwent the second NAFLD evaluation approximately 3 years later. α-Linolenic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in erythrocytes were measured by gas chromatography.

RESULTS

After adjusting for potential confounders, we observed inverse associations between DHA, DHA + EPA, total n-3 PUFAs and the presence of NAFLD in the cross-sectional analysis. The adjusted odds ratios (95% confidence interval) of NAFLD for the highest (vs. lowest) tertile were 0.74 (0.61, 0.90) for DHA, 0.82 (0.67, 1.00) for EPA, 0.73 (0.60, 0.88) for DHA + EPA and 0.74 (0.61, 0.91) for total n-3 PUFAs  (all P values≤0.05). Over the average 3.12 years of follow-up, higher levels of DHA was associated with an improvement of NAFLD. The hazard ratio of improved NAFLD for the highest tertile was 1.18 (95% CI 1.09, 1.33) for DHA. Pathway analyses showed that favorable associations may be mediated by improvements in inflammatory markers (e.g., interleukin 1 beta and tumor necrosis factor alpha-like).

CONCLUSIONS

Erythrocyte membrane n-3 PUFAs are inversely associated with the presence and progression of NAFLD in Chinese adults.

TRIAL REGISTRATIONS

ClinicalTrials.gov NCT03179657.

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.

Variation in the Plasma Levels of Polyunsaturated Fatty Acids in Control vis-à-vis Nonalcoholic Fatty Liver Disease Subjects and Its Possible Association with Gut Microbiome

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH) are becoming a major cause of chronic liver diseases globally. Polyunsaturated fatty acids (PUFA) have been postulated as a potential treatment for NAFLD. They can be obtained from diet and are also endogenously synthesized by enzymes delta-6-desaturase (D6D), delta-5-desaturase, and elongases. The current study is aimed at investigating the differences in the intake and levels of plasma PUFA between NAFLD patients and controls in Asian Indians. This correlation further propelled a pilot study to check for the differences in the gut microbiome of NASH subjects versus controls.

METHODS

One hundred forty-seven subjects were recruited and were grouped into healthy controls and cases. Subjects filled a food frequency questionnaire to assess PUFA intake. Plasma samples were subjected to gas chromatography analysis. For characterizing the gut microbiome, fecal samples of 20 NASH and healthy controls were analyzed by 16s rRNA gene sequencing. Alpha and beta diversity metrics and taxonomic analysis were carried out.

RESULTS

Plasma levels of eicosapentaenoic acid, γ-linoleic acid and D6D enzyme activity were significantly lower in cases. Dietary intake of total n-6 and n-3 PUFA did not differ between the two groups. Relative abundance of Streptococcus and Clostridium ramosum was significantly higher in NASH patients compared with healthy controls.

CONCLUSION

This study demonstrates, for the first time, decreased D6D enzyme activity and plasma PUFA levels in NAFLD patients. Furthermore, it demonstrates gut dysbiosis in histologically proven NASH patients vis-à-vis healthy controls.

Practical Dietary Recommendations for the Prevention and Management of Nonalcoholic Fatty Liver Disease in Adults

Nonalcoholic fatty liver disease (NAFLD) is the most common liver disease worldwide. In the absence of effective pharmacotherapies, clinical guidelines focus primarily on weight loss to treat this condition. Established consensus, evidence-based, and clinical dietary recommendations for NAFLD are currently lacking. The aim of this paper is to provide evidence-based practical dietary recommendations for the prevention and management of NAFLD in adults. A literature review focusing on established principles for the development of clinical practice recommendations was employed using the following criteria: based on substantial evidence, ensures risk minimization, is flexible for an individual patient approach, and is open to further modification as evidence emerges. The Practice-based Evidence in Nutrition classification system was used to grade these principles. Five key dietary recommendations were developed: 1) follow traditional dietary patterns, such as the Mediterranean diet; 2) limit excess fructose consumption and avoid processed foods and beverages with added fructose; 3) PUFAs, especially long-chain omega-3 rich foods and MUFAs, should replace SFAs in the diet; 4) replace processed food, fast food, commercial bakery goods, and sweets with unprocessed foods high in fiber, including whole grains, vegetables, fruits, legumes, nuts, and seeds; and 5) avoid excess alcohol consumption. Improving diet quality may reduce the incidence and progression of NAFLD and associated risk factors. Many of the benefits are likely to result from the collective effect of dietary patterns. High-quality research-in particular, randomized clinical trials assessing dietary interventions that focus on liver-specific endpoints-are needed as a priority.

New trends on obesity and NAFLD in Asia

Traditionally, obesity and its related diseases have been considered a problem in Western countries. However, in the past two decades, urbanisation in many Asian countries has led to a sedentary lifestyle and overnutrition, setting the stage for the epidemic of obesity. This article reviews the epidemiological trend of obesity in Asia, with special emphasis on the emerging condition of non-alcoholic fatty liver disease (NAFLD). Currently, the population prevalence of NAFLD in Asia is around 25%, like many Western countries. While hepatocellular carcinoma and end-stage liver disease secondary to NAFLD remain uncommon, a rising trend has emerged. Around 8-19% of Asians with body mass indexes less than 25kg/m² are also found to have NAFLD, a condition often described as "lean" or "non-obese" NAFLD. Although this condition is generally less severe than that in more obese patients, steatohepatitis and fibrotic disease are well recognized. Central adiposity, insulin resistance and weight gain are major risk factors, and genetic predisposition, such as the PNPLA3 polymorphism appears to be more important in the development of NAFLD in the non-obese population. Lifestyle modification remains the cornerstone of management for obesity and NAFLD, but few patients can achieve adequate weight reduction and even fewer can maintain the weight in the long run. While pharmacological agents have entered phase III development for steatohepatitis, Asian patients are under-represented in most drug trials. Future studies should define the optimal management of obesity and NAFLD in Asia.

Serum and Liver Tissue Metabonomic Study on Fatty Liver in Rats Induced by High-Fat Diet and Intervention Effects of Traditional Chinese Medicine Qushi Huayu Decoction

Qushi Huayu Decoction (QSHY), clinically derived, consists of five crude drugs, commonly used in treating fatty liver in a clinical setting. However, little is known about its metabolomics study. Herein, the serum and liver tissue metabolomics approach, based on gas chromatography coupled to spectrometry (GC/MS), was employed to evaluate the efficacy and the mechanism underlying QSHY in a rat model of high-fat diet-induced fatty liver. With pattern recognition analysis of serum and liver tissue metabolite profile, a clear separation of model group and control group was acquired for serum and liver tissue samples, respectively. The QSHY group showed a predisposition towards recovery mimicking the control group, which was in agreement with the biochemical alterations and histological results. 23 candidate biomarkers were identified in the serum and liver tissue samples that were utilized for exploring the underlying mechanism. The present study suggests that QSHY has significant anti-fatty liver effects on high-fat diet-induced fatty liver in rats, which might be attributed to regulating the dysfunction of beta-alanine metabolism, alanine, aspartate, and glutamate metabolism, glycine, serine, and threonine metabolism, pyruvate metabolism, and citrate cycle. Thus, metabolomics is a useful tool in the evaluation of the efficacy and elucidation of the mechanism underlying the complex traditional Chinese medicine prescriptions.

Association between rice, bread, and noodle intake and the prevalence of non-alcoholic fatty liver disease in Japanese middle-aged men and women

BACKGROUND & AIMS

Prevention of non-alcoholic fatty liver disease (NAFLD) through lifestyle modification is an important public health issue. Carbohydrate intake from soft drinks has received particular interest. Owing to differences in dietary habits, however, major contributors to the intake of dietary carbohydrates, such as rice, bread, and noodles, might have more influence on NAFLD prevalence in East Asian countries than consumption of soft drinks. We examined the relationship of the intake of rice, bread, and noodles, as well as overall carbohydrate intake, with NAFLD prevalence in middle-aged Japanese.

METHODS

This is a cross-sectional study of 977 men and 1467 women aged 40-69 y. Dietary information was obtained using a validated self-administered diet history questionnaire. Diagnosis of NAFLD was based on the following criteria: presence of steatosis on abdominal ultrasound, alcohol intake <20 g/day in women and <30 g/day in men, and exclusion of other liver diseases. Logistic regression was performed as multivariate analysis.

RESULTS

The presence of NAFLD was 34.9% (n = 341) in men and 11.7% (n = 171) in women. Carbohydrate intake was positively associated with NAFLD prevalence in women (p for trend = 0.008). There was also a positive association between rice intake and NAFLD prevalence in women; the multi-adjusted odds ratio for the highest versus the lowest quartiles of rice intake was 1.87 (95% CI: 1.03, 3.41; p for trend = 0.006). These associations were not observed in men. No association was observed between bread and noodle intake and the prevalence of NAFLD in either sex.

CONCLUSIONS

Consumption of carbohydrates and rice was positively associated with NAFLD prevalence in middle-aged Japanese women.

High fat plus high cholesterol diet lead to hepatic steatosis in zebrafish larvae: a novel model for screening anti-hepatic steatosis drugs

Background

Non-alcoholic fatty liver disease (NAFLD), characterized as excessive lipid accumulation within hepatocytes, is growing in prevalence. The exploitation of effective drugs for NAFLD has been proven challenging. Herein, we aimed to establish a dietary model of hepatic steatosis using transparent zebrafish larvae in which high-throughput chemical screens could be conducted.

Methods

Zebrafish larvae fed with high fat (HF) diet and high fat plus high cholesterol (HFC) diet were compared to the control. We analyzed intrahepatic lipid accumulation, biological indexes and various pathways including lipid metabolism, ER stress and inflammation. In addition, the effects of ezetimibe and simvastatin on HFC diet-induced steatosis were evaluated.

Results

Zebrafish larvae fed with HF and HFC diets developed steatosis for 7 and 10 days. The incidence and degree of steatosis were more severe in HFC diet-fed larvae compared with the control and HF diet-fed larvae, suggesting that adding cholesterol to the HF diet promotes the hepatic lipid accumulation. These data were confirmed by the pathological observation. Biological indexes, free cholesterol (FC), total cholesterol (TC) and triacylglycerol (TG) were elevated in the liver of HFC diet-fed larvae compared with the control and HF diet-fed larvae. Additionally, the expression levels of endoplasmic reticulum (ER) stress and lipolytic molecules (atf6, hspa5, hsp90b1, pparab, cpt1a and acox3) were significantly up-regulated in the liver of HF and HFC diets-fed larvae compared to the control, whereas the expression of lipogenic molecules (acaca, fasn, srebf2, hmgcs1 and hmgcra) were decreased in the liver of HF and HFC diets-fed larvae compared to the control. To validate the reliability of the HFC model and utility value for screening potential anti-steaotsis drugs, HFC-fed larvae were treated with two accepted lipid-lowing drugs (ezetimibe and simvastatin). The results showed that these drugs significantly ameliorated HFC-induced steatosis.

Conclusion

Our results demonstrate that the zebrafish larvae steatosis model established and validated in this study could be used for in vivo steatosis studies and drug screening.

Electronic supplementary material

The online version of this article (doi:10.1186/s12986-015-0036-z) contains supplementary material, which is available to authorized users.

Diet-Quality Scores and Prevalence of Nonalcoholic Fatty Liver Disease: A Population Study Using Proton-Magnetic Resonance Spectroscopy

Dietary pattern analysis is an alternative approach to examine the association between diet and nonalcoholic fatty liver disease (NAFLD). This study examined the association of two diet-quality scores, namely Diet Quality Index-International (DQI-I) and Mediterranean Diet Score (MDS) with NAFLD prevalence. Apparently healthy Chinese adults (332 male, 465 female) aged 18 years or above were recruited through a population screening between 2008 and 2010 in a cross-sectional population-based study in Hong Kong. DQI-I and MDS, as well as major food group and nutrient intakes were calculated based on dietary data from a food frequency questionnaire. NAFLD was defined as intrahepatic triglyceride content at ≥5% by proton-magnetic resonance spectroscopy. Multivariate logistic regression models were used to examine the association between each diet-quality score or dietary component and prevalent NAFLD with adjustment for potential lifestyle, metabolic and genetic factors. A total of 220 subjects (27.6%) were diagnosed with NAFLD. DQI-I but not MDS was associated with the prevalence of NAFLD. A 10-unit decrease in DQI-I was associated with 24% increase in the likelihood of having NAFLD in the age and sex adjusted model (95% CI: 1.06-1.45, p = 0.009), and the association remained significant when the model was further adjusted for other lifestyle factors, metabolic and genetic factors [OR: 1.26 (95% CI: 1.03-1.54), p = 0.027]. Multivariate regression analyses showed an inverse association of the intake of vegetables and legumes, fruits and dried fruits, as well as vitamin C with the NAFLD prevalence (p<0.05). In conclusion, a better diet quality as characterized by a higher DQI-I and a higher consumption of vegetables, legumes and fruits was associated with a reduced likelihood of having NAFLD in Hong Kong Chinese.

The relationship between the parenteral dose of fish oil supplementation and the variation of liver function tests in hospitalized adult patients

Background

Hepatic dysfunction is a complication associated with parenteral nutrition (PN). Our primary objective was to study the relationship between doses of intravenous fish oil (FO) emulsion in PN and the variation in the main liver function tests (LFTs) in hospitalized PN-treated adults. As a secondary objective, we studied the safety of FO administration.

Methods

We conducted a retrospective study in adult patients receiving FO supplementation in PN. Demographic, nutritional and safety variables were collected. Variation of LFTs was defined as the difference between values just before the first administration of FO and values at the end of PN. A multiple linear regression was performed to study the association between PN-lipids (FO or vegetable) and the variation of each LFT; the following variables were used to adjust the effect of lipids: sepsis, length of stay in the intensive care unit and lipids dose. Student t-test was used to study safety variables. Data were analyzed using SPSS 19.0.

Results

Patients (53, median age 68 years (24–90); 62 % men) with the principal diagnosis of digestive neoplasm (42 %) received PN for a median of 19 (7–75) days. In the multivariate analysis, the amount of FO was related to a decrease in gamma-glutamyl transferase (GGT) (B = −2.23;CI95 % = −4.41/-0.05), a decrease in alkaline phosphatase (AP) (B = −1.23;CI95 % = −2.07/-0.37), and a decrease in alanine aminotransferase (ALT) (B = −0.82; CI95 % = −1.19/-0.44). No differences were found in safety variables.

Conclusions

GGT, AP and ALT improved with FO PN-supplementation. Moreover, the improvement was greater when the doses of FO were higher. FO administration in PN is safe.

Eicosapentaenoic acid/arachidonic acid ratio as a possible link between non-alcoholic fatty liver disease and cardiovascular disease

AIM

The main causes of mortality from non-alcoholic fatty liver disease (NAFLD) are cardiovascular disease (CVD) and malignancy. Eicosapentaenoic acid (EPA)/arachidonic acid (AA) ratio is known to be associated with CVD. However, a possible link between EPA/AA ratio and NAFLD is not well known. In this study, we investigated EPA/AA ratio in Japanese patients with NAFLD.

METHODS

Two hundred and fifty-four patients with biopsy-proven NAFLD were retrospectively enrolled. Serum EPA/AA ratios were examined for each generation (<35, 35-44, 45-54, 55-64, ≥65 years), and the differences of EPA/AA ratios were evaluated based on steatotic grades and fibrotic stages.

RESULTS

EPA/AA ratio in NAFLD patients was decreased compared to that reported in age-matched healthy controls. EPA/AA ratio, body mass index, total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol and steatotic grades in younger NAFLD patients were significantly worse than those in older NAFLD patients. Fasting glucose, hemoglobin A1c and fibrotic stages in older NAFLD patients were significantly higher than those in younger NAFLD patients. No relation was found between EPA/AA ratio and histological findings.

CONCLUSION

EPA/AA ratio was lower in NAFLD, especially in younger NAFLD patients. Considering the high mortality from CVD in NAFLD patients, low EPA/AA ratio in young age may influence the increased prevalence of CVD in their older age. EPA/AA ratio is suggested to be a possible link between NAFLD and CVD, and would become a useful marker for CVD in NAFLD.

Dietary rapeseed/canola-oil supplementation reduces serum lipids and liver enzymes and alters postprandial inflammatory responses in adipose tissue compared to olive-oil supplementation in obese men

SCOPE

Obesity is associated with hyperlipidemia, hepatic steatosis, and low-grade inflammation. Studies have shown that MUFA as well as PUFA have beneficial effects on blood lipids and the inflammatory state.

METHODS AND RESULTS

This study investigates the effects of a daily supplementation of either 50 g of rapeseed/canola (RA) or olive (OL) oil over 4 wk on serum lipids, serum liver enzymes, and inflammatory gene expression in subcutaneous (s. c.) adipose tissue in obese men. Consuming RA resulted in increased serum n-3 fatty acids and a reduction in total cholesterol, LDL cholesterol, and serum aspartate aminotransferase compared to OL. In s. c. adipose tissue, gene expression of the pro-inflammatory cytokine IL6 was reduced in RA compared to OL. However, after 4 h after a test meal, containing the appropriate oil, white bread, and 400 mL of liquid diet drink (835 kcal in total), gene expression of IL6, IL1B, and EMR1 (egf-like module containing Mucin-like hormone receptor-like 1) was increased in RA and of monocyte chemoattractant protein-1 (CCL2) in both RA and OL.

CONCLUSION

This demonstrates that consuming RA for 4 wk improves serum lipids, liver enzymes, and basal inflammation in s. c. adipose tissue, but it mediates an acute pro-inflammatory response in adipose tissue upon consuming a meal.

Role of diet and lifestyle changes in nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) has become one of the most common causes of liver disease worldwide and has been recognized as a major health burden. The prevalence of NAFLD has grown proportionally with the rise in obesity, sedentary lifestyle, unhealthy dietary pattern, and metabolic syndrome. Currently, there is no drug therapy that can be formulated for treating NAFLD. A combination of dietary modifications and increased physical activity remains the mainstay of NAFLD management. It is hard to maintain this mode of management; however, it seems to have significant long-term benefits. Furthermore, NAFLD patients, whether obese or not, should be educated that a healthy diet and physical activity have benefits beyond weight reduction. Further large controlled randomized trials are needed in order to identify the best dietary regimen and physical activity in the management of NAFLD patients. This review highlights the role of diet and lifestyle modifications in the management of NAFLD, and focuses on human studies regarding dietary modifications and physical activity.

Polyunsaturated fatty acids balance affects platelet NOX2 activity in patients with liver cirrhosis

BACKGROUND

NADPH-oxidase-2 up-regulation has been suggested in liver damage perpetuation via an oxidative stress-mediated mechanism. n-6/n-3 polyunsaturated fatty acids ratio derangement has been reported in liver disease.

AIM

To explore polyunsaturated fatty acids balance and its interplay with platelet oxidative stress in liver cirrhosis.

METHODS

A cross-sectional study in 51 cirrhotic patients and sex- and age-matched controls was performed. Serum polyunsaturated fatty acids and oxidative stress markers (urinary isoprostanes and serum soluble NADPH-oxidase-2-derived peptide) were measured. The effect on platelet oxidative stress of n-6/n-3 polyunsaturated fatty acids ratio in vitro and in vivo (1-week supplementation with 3g/daily n-3-polyunsaturated fatty acids) was tested.

RESULTS

Compared to controls, cirrhotic patients had significantly higher n-6/n-3 polyunsaturated fatty acids ratio. n-6/n-3 polyunsaturated fatty acids ratio correlated significantly with disease severity and oxidative stress markers. In vitro experiments showed that in Child-Pugh C patients' platelets incubation with low n-6/n-3 polyunsaturated fatty acids ratio resulted in dose-dependent decrease of radical oxigen species (-39%), isoprostanes (-25%) and NADPH-oxidase-2 regulation (-51%). n-3 polyunsaturated fatty acids supplemented patients showed significant oxidative stress indexes reduction.

CONCLUSIONS

In cirrhosis, n-6/n-3 polyunsaturated fatty acids imbalance up-regulates platelet NADPH-oxidase-2 with ensuing oxidative stress. Further study to evaluate if n-3 supplementation may reduce disease progression is warranted.

Chemoprevention of nonalcoholic fatty liver disease by dietary natural compounds

Nonalcoholic fatty liver disease (NAFLD) refers to a wide spectrum of liver disease that is not from excess alcohol consumption, but is often associated with obesity, type 2 diabetes, and metabolic syndrome. NAFLD pathogenesis is complicated and involves oxidative stress, lipotoxicity, mitochondrial damage, insulin resistance, inflammation, and excessive dietary fat intake, which increase hepatic lipid influx and de novo lipogenesis and impair insulin signaling, thus promoting hepatic triglyceride accumulation and ultimately NAFLD. Overproduction of proinflammatory adipokines from adipose tissue also affects hepatic metabolic function. Current NAFLD therapies are limited; thus, much attention has been focused on identification of potential dietary substances from fruits, vegetables, and edible plants to provide a new strategy for NAFLD treatment. Dietary natural compounds, such as carotenoids, omega-3-PUFAs, flavonoids, isothiocyanates, terpenoids, curcumin, and resveratrol, act through a variety of mechanisms to prevent and improve NAFLD. Here, we summarize and briefly discuss the currently known targets and signaling pathways as well as the role of dietary natural compounds that interfere with NAFLD pathogenesis.

Nonalcoholic fatty liver disease: an emerging threat to obese and diabetic individuals

Nonalcoholic fatty liver disease (NAFLD) is the most common liver disease in the Western world and its incidence is increasing rapidly. NAFLD is a spectrum ranging from simple steatosis, which is relatively benign hepatically, to nonalcoholic steatohepatitis (NASH), which can progress to cirrhosis. Obesity, insulin resistance, type 2 diabetes mellitus, and dyslipidemia are the most important risk factors for NAFLD. Due to heavy enrichment with metabolic risk factors, individuals with NAFLD are at significantly higher risk for cardiovascular disease. Individuals with NAFLD have higher incidence of type 2 diabetes. The diagnosis of NAFLD requires imaging evidence of hepatic steatosis in the absence of competing etiologies including significant alcohol consumption. Liver biopsy remains the gold standard for diagnosing NASH and for determining prognosis. Weight loss remains a cornerstone of treatment. Weight loss of ∼5% is believed to improve steatosis, whereas ∼10% weight loss is necessary to improve steatohepatitis. A number of pharmacologic therapies have been investigated to treat NASH, and agents such as vitamin E and thiazolidinediones have shown promise in select patient subgroups.

Chronic HCV infection was associated with severe insulin resistance and mild atherosclerosis: a population-based study in an HCV hyperendemic area

BACKGROUND

Hepatitis C virus (HCV) affects glucose and lipid metabolism in vitro; however, it is unclear whether HCV infection is associated with insulin resistance and atherosclerosis at the population level. We aimed to investigate this association in a Japanese cohort of the Seven Countries Study, and our investigation was conducted in Tanushimaru, an HCV hyperendemic area.

METHODS

A total of 1908 inhabitants of Tanushimaru were classified into 3 groups according to HCV infection status: those who were uninfected (n = 1780), those with transient infection (n = 88), and those with chronic infection (n = 40). Insulin resistance and atherosclerosis were evaluated by homeostasis model assessment for insulin resistance (HOMA-IR) and carotid intima-media thickness (IMT), respectively. Intergroup differences in variables were evaluated by age- and sex-matched multivariate regression analysis.

RESULTS

Significant intergroup differences were seen in fasting glucose and insulin levels. The HOMA-IR value was significantly higher in the group with chronic infection than the values in the uninfected and transiently infected groups (3.0 ± 0.39 vs. 1.3 ± 0.03 vs. 1.5 ± 0.14; P < 0.001). In contrast, low-density lipoprotein (LDL)-cholesterol and triglyceride levels were significantly lower in the group with chronic infection than the levels in the other groups. IMT was reduced in the group with chronic infection, with a significant intergroup difference (0.67 ± 0.02 vs. 0.71 ± 0.003 vs. 0.72 ± 0.01 mm; P = 0.003).

CONCLUSIONS

This population-based study in an HCV hyperendemic area revealed that chronic HCV infection was associated with severe insulin resistance and with mild atherosclerosis, suggesting a unique characteristic of HCV-related metabolic abnormality.

Menhaden oil decreases high-fat diet-induced markers of hepatic damage, steatosis, inflammation, and fibrosis in obese Ldlr-/- mice

The frequency of nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH) has increased in parallel with obesity in the United States. NASH is progressive and characterized by hepatic damage, inflammation, fibrosis, and oxidative stress. Because C20-22 (n-3) PUFA are established regulators of lipid metabolism and inflammation, we tested the hypothesis that C20-22 (n-3) PUFA in menhaden oil (MO) prevent high-fat (HF) diet-induced fatty liver disease in mice. Wild-type (WT) and Ldlr(-/-) C57BL/6J mice were fed the following diets for 12 wk: nonpurified (NP), HF with lard (60% of energy from fat), HF-high-cholesterol with olive oil (HFHC-OO; 54.4% of energy from fat, 0.5% cholesterol), or HFHC-OO supplemented with MO (HFHC-MO). When compared with the NP diet, the HF and HFHC-OO diets induced hepatosteatosis and hepatic damage [elevated plasma alanine aminotransferase (ALT) and aspartate aminotransferases] and elevated hepatic expression of markers of inflammation (monocyte chemoattractant protein-1), fibrosis (procollagen 1α1), and oxidative stress (heme oxygenase-1) (P ≤ 0.05). Hepatic damage (i.e., ALT) correlated (r = 0.74, P < 0.05) with quantitatively higher (>140%, P < 0.05) hepatic cholesterol in Ldlr(-/-) mice fed the HFHC-OO diet than WT mice fed the HF or HFHC-OO diets. Plasma and hepatic markers of liver damage, steatosis, inflammation, and fibrosis, but not oxidative stress, were lower in WT and Ldlr(-/-) mice fed the HFHC-MO diet compared with the HFHC-OO diet (P < 0.05). In conclusion, MO [C20-22 (n-3) PUFA at 2% of energy] decreases many, but not all, HF diet-induced markers of fatty liver disease in mice.

The role of nutrients in the development, progression, and treatment of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of liver disease in adults and children and is currently the third most common indication for liver transplantation in North America. Its pathogenesis is thought to be secondary to multiple "hits" derived from the dietary components, adipose tissue, immune system, and intestinal microbiota. Lack of physical activity may contribute as well. Nutrients may exert their effect directly or through alteration of the intestinal microbiota. Research focusing on specific dietary components predisposing to NAFLD has shown conflicting results. Total energy intake, and macronutrients, has been linked to the development of NAFLD. Fructose not only contributes to hepatic steatosis but may trigger inflammatory signals as well. Polyunsaturated fatty acids are thought to exert anti-inflammatory effects. The role of vitamins as well as minerals in this field is actively being investigated. In this review, we discuss the evidence-linking macronutrients (such as carbohydrates and fat in general and fructose, fiber, short chain fatty acids, polyunsaturated fatty, and choline specifically) and micronutrients (such as vitamin E and C and minerals) with the development and treatment of NAFLD. We also discuss the literature on physical activity and NAFLD.

A short-term n-3 DPA supplementation study in humans

PURPOSE

Despite the detailed knowledge of the absorption and incorporation of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) into plasma lipids and red blood cells (RBC) in humans, very little is known about docosapentaenoic acid (DPA, 22:5 n-3). The aim of this study was to investigate the uptake and incorporation of pure DPA and EPA into human plasma and RBC lipids.

METHODS

Ten female participants received 8 g of pure DPA or pure EPA in randomized crossover double-blinded manner over a 7-day period. The placebo treatment was olive oil. Blood samples were collected at days zero, four and seven, following which the plasma and RBC were separated and used for the analysis of fatty acids.

RESULTS

Supplementation with DPA significantly increased the proportions of DPA in the plasma phospholipids (PL) (by twofold) and triacylglycerol (TAG) fractions (by 2.3-fold, day 4). DPA supplementation also significantly increased the proportions of EPA in TAG (by 3.1-fold, day 4) and cholesterol ester (CE) fractions (by 2.0-fold, day 7) and of DHA in TAG fraction (by 3.1-fold, day 4). DPA proportions in RBC PL did not change following supplementation. Supplementation with EPA significantly increased the proportion of EPA in the plasma CE and PL fractions, (both by 2.7-fold, day 4 and day 7) and in the RBC PL (by 1.9-fold, day 4 and day 7). EPA supplementation did not alter the proportions of DPA or DHA in any lipid fraction. These results showed that within day 4 of supplementation, DPA and EPA demonstrated different and specific incorporation patterns.

CONCLUSION

The results of this short-term study suggest that DPA may act as a reservoir of the major long-chain n-3 fatty acids (LC n-3 PUFA) in humans.

Epidemiology of a fast emerging disease in the Asia-Pacific region: non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is rapidly increasing in the Asia-Pacific and affects up to 30 % of the general population. In younger children, prevalence has been reported to be between 2.1 and 4.5 %. The prevalence of NAFLD increases with increasing age. NAFLD is more prevalent in men than women, but this trend fades in older age group. NAFLD is one of the most common causes of raised serum ALT levels and the latter is closely related to the presence of features of metabolic syndrome. NAFLD may contribute to metabolic syndrome in a similar way as visceral adiposity and can be an early predictor of metabolic disorders. NAFLD increases the risk of developing diabetes mellitus and is closely related to degree of glucose intolerance. A significant proportion of patients with NAFLD have impaired glucose tolerance or diabetes mellitus but with normal fasting blood glucose, highlighting the importance of oral glucose tolerance test in NAFLD patients with normal fasting blood glucose. Besides liver-related complications, NAFLD has been associated with cardiovascular complications, hyperuricemia, gout, chronic kidney disease, gallstone disease, colorectal adenomatous polyp, and polycystic ovarian syndrome. NAFLD seems to be related to host metabolic factors rather than viral factors and does not seem to affect severity of the liver disease in patients with chronic hepatitis B. On the other hand, hepatic steatosis may be related to both host metabolic and viral factors in patients with chronic hepatitis C and seems to adversely impact on the severity of liver disease and possibly response to antiviral therapy.

Low docosahexaenoic acid content in plasma phospholipids is associated with increased non-alcoholic fatty liver disease in China

A large proportion of the Chinese population is now at risk of non-alcoholic fatty liver disease (NAFLD). We aimed to investigate the relationship between plasma phospholipids (PL) fatty acids and the risk of NAFLD. One hundred NAFLD patients and 100 healthy subjects were recruited in Hangzhou, China. Plasma PL and selected biochemical and hematological parameters were analyzed by using standard methods. Stepwise logistic regression was used to identify independent risk factors of NAFLD. Plasma PL total saturated fatty acid (SFA), C20:3n-6, serum alanine aminotransferase, high-density lipoprotein cholesterol, and body mass index were independent risk factors of NAFLD. The risk of NAFLD was significantly increased with higher quartiles of plasma PL total SFA (P for trend = 0.028) and C20:3n-6 (P for trend <0.001); plasma PL docosahexaenoic acid (C22:6n-3) was significantly lower in NAFLD patients than in controls (P = 0.032) and the OR of NAFLD in the highest quartile of C22:6n-3 was 0.41 (95 % CI = 0.17-0.97) compared with the lowest quartile. In conclusion, plasma PL total SFA and C20:3n-6 are positively correlated with the risk of NAFLD, while C22:6n-3 is negatively correlated with the risk of NAFLD.

Docosahexaenoic acid ameliorates palmitate-induced lipid accumulation and inflammation through repressing NLRC4 inflammasome activation in HepG2 cells

Background

N-3 polyunsaturated fatty acids, such as docosahexaenoic acid (DHA; 22:6n-3), has clinical significance in the prevention and reversal of nonalcoholic steatohepatitis (NASH). However, the precious mechanism underlying remains unclear. The inflammasome, a multiprotein complex formed by NOD-like receptor (NLR) family members, has been recently shown to be activated in NASH and promote the cleavage of the pro-inflammatory cytokines to their maturation forms.

Methods

HepG2 cells were exposed to different dose of PA for 24 h with or without the preincubation of 50 μM DHA for another 24 h and then lipid deposition was assessed with Oil red O staining and intracellular triglyceride (TG) determination. Secretory levels of inflammatory cytokines and Caspase-1 activity were determined by ELISA assays. Gene expression and protein levels were determined by quantitative RCR and western blotting, respectively.

Results

Palmitate (PA) dose-dependently increased lipid accumulation, TG content and induced the secretion of interleukin-1β (IL-1β), IL-18, TNF-α and MCP-1 from HepG2 cells. Preincubation with DHA significantly alleviated PA-induced lipid accumulation and inflammatory agents. DHA was also found to attenuate PA-induced NOD-like receptor protein 4 (NLRC4) mRNA expression. Furthermore, PA induced caspase-1 activation in a dose-dependent manner, resulting in exacerbating of procaspase-1 and pro-IL-1β processing. Knockdown of NLRC4 partially abrogated PA-induced caspase-1 activation and IL-1β maturation and completely abolished these events in the presence of DHA.

Conclusions

Our findings indicate DHA attenuates PA-induced lipid accumulation and inflammation through suppressing NLRC4 inflammasome activation, caspase-1 activation and IL-1β cleavage.

Nonalcoholic fatty liver disease: a review of the spectrum of disease, diagnosis, and therapy

Worldwide, there is an epidemic of obesity and overweight, with two-thirds of Americans affected. A strong association exists between excessive body weight and nonalcoholic fatty liver disease (NAFLD), the most common etiology of abnormal liver function tests. Nonalcoholic fatty liver disease is a spectrum of liver disease, from a "bland" fatty infiltration to chronic hepatitis (nonalcoholic steatohepatitis or NASH), that can result in cirrhosis and organ failure. With the increasing prevalence of obesity in the world, the proportion of people affected by NAFLD is only expected to be parallel. Although primarily noted in obese individuals, NAFLD has also been associated with a number of surgical procedures, metabolic conditions, and medications. NASH is commonly underdiagnosed as most affected patients are symptom free, and routine screening is not performed. Noninvasive diagnostic testing is not sensitive in diagnosis or staging the severity of disease. Fatty infiltration and oxidative injury to the hepatocytes are believed to be the major factors behind the progression of disease from simple fatty infiltration of the liver to chronic hepatitis. Understanding the inflammatory pathways involved in NASH is a subject of extensive research. Currently, few proven treatment options exist, and controlled weight reduction is the only safe modality recommended for treatment of NASH.

Stearidonic acid: is there a role in the prevention and management of type 2 diabetes mellitus?

Obesity and its related comorbidities are major public health concerns in the United States with over two-thirds of adults and one-third of children classified as overweight or obese. The prevalence of type 2 diabetes mellitus (T2DM) has similarly risen to an estimated 25.8 million, which accounts for a staggering $174 billion in annual healthcare costs. Identification of dietary interventions that protect against the development of T2DM would markedly reduce the medical and economic consequences of the disease. Hence, we review current evidence supporting a role of (n-3) PUFA in T2DM and explore potential therapeutic implications of stearidonic acid (SDA). The low consumption of fish in the US along with a reduced efficiency to interconvert most plant (n-3) PUFA highlights a need to find alternative sources of (n-3) PUFA. The efficient biological conversion of SDA to EPA underscores the potential implications of SDA as a source of (n-3) PUFA. The full therapeutic efficacy of SDA remains to be further determined. However, recent data have suggested a protective role of SDA consumption on markers of dyslipidemia and inflammation. The AHA recommends that healthy individuals consume oily fish at least twice per week and individuals with a history of cardiovascular disease consume 1 g of EPA+DHA/d. These goals will likely not be met by the typical American diet. Therefore, SDA may represent a sustainable alternative to marine-based (n-3) PUFA and may have novel therapeutic efficacy regarding the development of T2DM.

Multidisciplinary pharmacotherapeutic options for nonalcoholic Fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) are multidisciplinary liver diseases that often accompany type 2 diabetes or metabolic syndrome, which are characterized by insulin resistance. Therefore, effective treatment of type 2 diabetes and metabolic syndrome should target not only the cardiometabolic abnormalities, but also the associated liver disorders. In the last decade, it has been shown that metformin, thiazolidinediones, vitamin E, ezetimibe, n-3 polyunsaturated fatty acids, renin-angiotensin system (RAS) blockers, and antiobesity drugs may improve hepatic pathophysiological disorders as well as clinical parameters. Accordingly, insulin sensitizers, antioxidative agents, Niemann-Pick C1-like 1 (NPC1L1) inhibitors, RAS blockers, and drugs that target the central nervous system may represent candidate pharmacotherapies for NAFLD and possibly NASH. However, the efficacy, safety, and tolerability of long-term treatment (potentially for many years) with these drugs have not been fully established. Furthermore, clinical trials have not comprehensively examined the efficacy of lipid-lowering drugs (i.e., statins, fibrates, and NPC1L1 inhibitors) for the treatment of NAFLD. Although clinical evidence for RAS blockers and incretin-based agents (GLP-1 analogs and dipeptidyl peptidase-4 inhibitors) is also lacking, these agents are promising in terms of their insulin-sensitizing and anti-inflammatory effects without causing weight gain.

Increased erythrocytes n-3 and n-6 polyunsaturated fatty acids is significantly associated with a lower prevalence of steatosis in patients with type 2 diabetes

BACKGROUND & AIMS

Non-alcoholic fatty liver disease (NAFLD) is commonly associated with obesity, metabolic syndrome and type 2 diabetes. Although dietary fat contributes substantially to the accumulation of liver fat, the role of individual fatty acids in this accumulation is unclear.

OBJECTIVE

In this study, we set out to determine whether liver fat content (LFC), was associated with red blood cell fatty acid (RBC-FA) composition in people with type 2 diabetes.

DESIGN, SETTINGS, AND PARTICIPANTS

One hundred and sixty-two type 2 diabetic patients were included in this study. LFC was measured using (1)H-MR Spectroscopy. RBC-FA composition was measured by gas chromatography.

RESULTS

One hundred and nine (67.2%) patients had steatosis. Patients with steatosis had a higher BMI (p = 0.0005), and higher plasma triglyceride levels (p = 0.009) than did patients without steatosis. We report a significant association between palmitic acid (16:0), palmitoleic acid (16:1n-7) concentrations and ratio of monounsaturated to saturated fatty acid (palmitoleic acid to palmitic acid) and higher liver fat content. Total polyunsaturated fatty acid (PUFA), homo-gamma-linolenic acid (20:3n-6), docosahexaenoic acid (22:6n-3), and arachidonic acid (20:4 n-6) were associated with lower LFC.

CONCLUSIONS

Our data showed that an increased erythrocytes long-chain n-3 and n-6 fatty acids was associated with a lower prevalence of steatosis in patients with type 2 diabetes. These results suggest that n-3 and n-6 fatty acids supplementation could be a promising treatment for NAFLD in patients with type 2 diabetes.