Effect of dietary intervention, with or without co-interventions, on inflammatory markers in patients with nonalcoholic fatty liver disease: a systematic literature review

Effects of low fat diet on inflammatory parameters in individuals with obesity/overweight and non-alcoholic fatty liver disease: A cross-sectional study

Nonalcoholic fatty liver disease (NAFLD) is considered one of the most important causes of chronic liver disorders in the world. Dietary pattern is a modifiable risk factor that represents the main target for the prevention and treatment of NAFLD. The aim of this cross-sectional study was to assess the impact of low-fat diet on anthropometric measurements, biochemical, and inflammatory parameters in individuals with obesity/overweight and NAFLD. A total of 108 individuals (n = 59 males and n = 49 females) aged between 19 and 65 years participated in the 12-week weight loss program. Dietary treatment plans including low-fat diets were randomly prescribed for each individual. Anthropometric measurements were collected by a trained dietitian at baseline and 12-week follow-up. Blood samples were collected for each individual at baseline and 3rd month for biochemical measurements and enzyme-linked immunosorbent assay analysis for tumor necrosis factor-α (TNF-α), interleukin (IL)-6, fibroblast growth factor-21 (FGF-21), chemerin, and irisin levels in plasma. At the end of the study, body weight, body mass index, body fat % body fat mass (kg) reduced significantly in females and males (P < .05). Moreover, reductions in waist, hip, and neck circumferences were significant in both groups. Changes in alanine aminotransferase and aspartate aminotransferase levels were significant in 3rd month. After 3 months, reductions in TNF-α, IL-6, and FGF-21 levels were significant in individuals with obesity/overweight and NAFLD. While no significant change in chemerin and irisin levels was found. These results show that low-fat diet over a 12-week period led to improvements in both anthropometric measurements and biochemical parameters in individuals with obesity/overweight and NAFLD.

The association between dietary inflammatory index (DII) scores and c-reactive protein (CRP) and nonalcoholic fatty liver disease (NAFLD) in a general population cohort

BACKGROUND AND AIMS

Although there is extensive literature showing the ability of the dietary inflammation index (DII®) to predict concentrations of plasma inflammatory markers, few studies are testing the association between DII scores and nonalcoholic fatty liver disease (NAFLD). Considering the high prevalence of NAFLD and its complications, we conducted a validation study of DII scores and examined its association with NAFLD in the general adult population of Iran.

METHODS

This cross-sectional study was conducted on 3110 adult participants in the Amol Cohort Study (AmolCS) who underwent abdominal ultrasonography to diagnose NAFLD. DII and energy-adjusted DII (E-DII™) scores were computed using data from a valid semi-quantitative 168-item food frequency questionnaire (FFQ). Multivariable logistic regression adjusting for socio-demographic, lifestyle, and health-related factors was used to assess association.

RESULTS

The EDII was associated with CRP inflammatory biomarker. Participants in the highest, i.e., most pro-inflammatory tertile had the highest odds of NAFLD by ultrasound in all models [fully adjusted model: OR (95 % CI) tertile3vs.1:1.54 (1.05-2.05); Ptrend = 0.04, and 1.63 (1.19-2.21); Ptrend = 0.03 in women and men, respectively]. The highest tertile had the highest OR for NAFLD by fatty liver index (FLI) only in men [fully adjusted model OR (95 % CI) tertile3vs.1: 1.77 (1.15-2.71); Ptrend = 0.01]. Similar results were also obtained for NAFLD by hepatic steatosis index (HSI) in women [fully adjusted model: OR (95 % CI) tertile3vs.1: 1.70 (1.12-2.58); Ptrend = 0.03]. The results of the fully adjusted multivariable model of liver markers and NAFLD status, stratified by gender and abdominal obesity, revealed that the highest tertiles had the highest OR for NAFLD by ultrasound and NAFLD by FLI only in men without abdominal obesity [fully adjusted model: OR (95 % CI) tertile3vs.1: 1.83 (1.17-2.84); Ptrend = 0.03, and, respectively]. NAFLD by FLI tended to increase strongly with tertile E-DII scores in men without abdominal obesity in crude and three adjusted models [full-adjusted model: OR (95 % CI) tertile3vs.1: 3.64 (1.56-8.46); Ptrend = 0.005]. By contrast, women with abdominal obesity in the highest tertile had the highest OR for NAFLD by ultrasound in all models [full-adjusted model: OR (95 % CI) tertile3vs.1: 1.67 (1.07-2.62); Ptrend = 0.02].

CONCLUSIONS

Our results suggest that diet plays a role in regulating inflammation. Additionally, we observed an inflammatory diet predicts the risk of NAFLD in Iranian adults. However, longitudinal studies are required in order to further substantiate the utility of the DII in the development of more effective dietary interventions among populations at risk of chronic disease.

Adherence to a Mediterranean diet may improve serum adiponectin in adults with nonalcoholic fatty liver disease: The MEDINA randomized controlled trial

Nonalcoholic fatty liver disease (NAFLD) affects approximately 30% of adults worldwide, with chronic low-grade inflammation being a key pathophysiological feature of progression. The Mediterranean diet (MedDiet) is recognized for improving metabolic and hepatic outcomes in people with diabetes and NAFLD, in part, via anti-inflammatory properties. The aim of this study was to determine the effect of an ad libitum MedDiet versus low-fat diet (LFD) on inflammatory markers in adults with NAFLD. It was hypothesized that the MedDiet, and its individual components, would improve inflammation. This multicenter, randomized controlled trial, randomized participants to a MedDiet or LFD intervention for 12 weeks. Primary outcomes included change from baseline to 12 weeks for serum high-sensitivity C-reactive protein, interleukin-6, tumor necrosis factor-α, adiponectin, leptin, and resistin. Forty-two participants (60% female; age 52.3 ± 12.6 years; body mass index, 32.2 ± 6.2 kg/m²) were randomized to the MedDiet (n = 19) or low-fat diet (n = 23). At 12 weeks, the LFD showed a greater decrease in leptin compared with the MedDiet (-1.20 ± 3.9 ng/mL vs 0.64 ± 3.5 ng/mL, P = .010). Adiponectin significantly improved within the MedDiet (13.7 ± 9.2 µg/mL to 17.0 ± 12.5 µg/mL, P = .016), but not within the LFD group. No statistically significant changes were observed for other inflammatory markers following the MedDiet or LFD. Adherence to the MedDiet significantly improved in both study arms, although greater improvements were seen in the MedDiet group. Adiponectin significantly improved following a Mediterranean diet intervention, in the absence of weight loss. The low-fat diet did not elicit improvements in inflammatory markers. High-quality clinical trials appropriately powered to inflammatory markers are required in this population.

Identifying Patients with Nonalcoholic Fatty Liver Disease in Primary Care: How and for What Benefit?

Despite its increasing prevalence, nonalcoholic fatty liver disease (NAFLD) remains under-diagnosed in primary care. Timely diagnosis is critical, as NAFLD can progress to nonalcoholic steatohepatitis, fibrosis, cirrhosis, hepatocellular carcinoma, and death; furthermore, NAFLD is also a risk factor linked to cardiometabolic outcomes. Identifying patients with NAFLD, and particularly those at risk of advanced fibrosis, is important so that healthcare practitioners can optimize care delivery in an effort to prevent disease progression. This review debates the practical issues that primary care physicians encounter when managing NAFLD, using a patient case study to illustrate the challenges and decisions that physicians face. It explores the pros and cons of different diagnostic strategies and tools that physicians can adopt in primary care settings, depending on how NAFLD presents and progresses. We discuss the importance of prescribing lifestyle changes to achieve weight loss and mitigate disease progression. A diagnostic and management flow chart is provided, showing the key points of assessment for primary care physicians. The advantages and disadvantages of advanced fibrosis risk assessments in primary care settings and the factors that influence patient referral to a hepatologist are also reviewed.

Effect of Dietary Intervention, with or without Cointerventions, on Inflammatory Markers in Patients with Nonalcoholic Fatty Liver Disease: A Systematic Review and Meta-Analysis

Nonalcoholic fatty liver disease (NAFLD) encompasses a spectrum of disease from simple steatosis to nonalcoholic steatohepatitis, with inflammatory cytokines and adipokines identified as drivers of disease progression. Poor dietary patterns are known to promote an inflammatory milieu, although the effects of specific diets remain largely unknown. This review aimed to gather and summarize new and existing evidence on the effect of dietary intervention on inflammatory markers in patients with NAFLD. The electronic databases MEDLINE, EMBASE, CINAHL, and Cochrane were searched for clinical trials which investigated outcomes of inflammatory cytokines and adipokines. Eligible studies included adults >18 y with NAFLD, which compared a dietary intervention with an alternative diet or control (no intervention) group or were accompanied by supplementation or other lifestyle interventions. Outcomes for inflammatory markers were grouped and pooled for meta-analysis where heterogeneity was allowed. Methodological quality and risk of bias were assessed using the Academy of Nutrition and Dietetics Criteria. Overall, 44 studies with a total of 2579 participants were included. Meta-analyses indicated intervention with an isocaloric diet plus supplement was more effective in reducing C-reactive protein (CRP) [standard mean difference (SMD): 0.44; 95% CI: 0.20, 0.68; P = 0.0003] and tumor necrosis factor-alpha (TNF-α) (SMD: 0.74; 95% CI: 0.02, 1.46; P = 0.03) than an isocaloric diet alone. No significant weighting was shown between a hypocaloric diet with or without supplementation for CRP (SMD: 0.30; 95% CI: -0.84, 1.44; P = 0.60) and TNF-α (SMD: 0.01; 95% CI: -0.43, 0.45; P = 0.97). In conclusion, hypocaloric and energy-restricted diets alone or with supplementation, and isocaloric diets with supplementation were shown to be most effective in improving the inflammatory profile of patients with NAFLD. To better determine the effectiveness of dietary intervention alone on a NAFLD population, further investigations of longer durations, with larger sample sizes are required.

Effects of anti-inflammatory dietary patterns on non-alcoholic fatty liver disease: a systematic literature review

PURPOSE

Non-alcoholic fatty liver disease (NAFLD) is the leading chronic hepatic condition. Low-grade chronic inflammation contributes to disease progression. Diet has protective effects on hepatic health and inflammatory pathways. The purpose of this review is to systematically review and describe the effects of anti-inflammatory dietary patterns on NAFLD.

METHODS

The Cochrane CENTRAL Library, Cumulative Index of Nursing and Allied Health Literature, Embase, MEDLINE and Web of Science databases were searched. A total of 252 records were identified, 7 of which were included in this review. The revised Cochrane risk-of-bias tool was used to conduct a quality assessment for randomised trials. Certainty of evidence was assessed using the grading of recommendations, assessment, development, and evaluation tool.

RESULTS

Of the 7 included studies, 6 were classified as low risk of bias and studies ranged from high to very low certainty of evidence. In the randomised-controlled studies systematically reviewed, either adherence to the Mediterranean, DASH, or FLiO diet was studied, against usual care or energy matched controls, with a total of 255 participants. Anti-inflammatory dietary pattern adherence significantly reduced the severity of most hepatic and inflammatory markers, and secondary outcomes. A minority of outcomes were improved significantly more than controls.

CONCLUSION

Anti-inflammatory dietary patterns showed benefits to NAFLD risk factors, severity markers and inflammatory markers compared to the control diet. It is unclear whether reductions in the evaluated parameters are related solely to the anti-inflammatory diet or weight loss resulting from caloric restriction, as improvements in control groups were also evidenced. Current limited body of evidence indicates need for further research including isocaloric dietary patterns, longer interventions, measures of inflammatory markers, and studies including normal-weight subjects to confirm findings at higher certainty.

PROSPERO REGISTRATION

CRD42021269382.

Do MAFLD Patients with Harmful Alcohol Consumption Have a Different Dietary Intake?

The term metabolic-associated fatty liver disease (MAFLD) has been proposed to define positively fatty liver disease in the form associated with metabolic risk factors. The aim of this study was to assess the dietary intake of MAFLD and explore a possible relationship between its inflammatory characteristics (assessed by Dietary Inflammatory Index—DII^®), the degree of liver fibrosis (assessed by transient elastography), and the amount of alcohol intake. MAFLD patients were included (n = 161) and were classified, according to the amount of alcoholic intake, as MAFLD without alcohol intake (n = 77) and MAFLD with alcohol intake (n = 84), with 19 presenting harmful alcoholic consumption. Dietary intake was 1868 ± 415 kcal/day and did not present differences in energy or nutrient intake based on the presence of metabolic comorbidities. Patients with MAFLD and alcohol intake consumed significantly more energy and presented a tendency for higher intake of carbohydrates and sugar. Patients with harmful alcohol intake presented a higher intake of total fat and cholesterol compared with moderate alcohol intake. There were no differences in DII^® based on fibrosis severity or the amount of alcohol consumption. This work contributes to the characterization of baseline dietary intake in MAFLD patients, paving the way to design more suited dietary interventional trials.

Association of poultry consumption with cardiovascular diseases and all-cause mortality: a systematic review and dose response meta-analysis of prospective cohort studies

According to previous cohort studies it is suggested that a high intake of poultry does not adversely affect cardiovascular disease (CVD) risk. Therefore, the aim of this systematic review and meta-analysis is to summarize and analyze the association between dietary poultry intake and the risk for CVDs, coronary heart disease (CHD), stroke and all-cause mortality (ACM). Twenty-four cohort studies were included, and the results showed a trivial inverse association for the highest vs. lowest intake category between poultry and ACM (risk ratio [RR] = 0.96; 95% CI: 0.93, 0.98; I² = 5%). For all other outcomes no association was observed in the high vs. low intake meta-analysis. The results from the primary pooled data for each 100 g/d increase in poultry intake indicated no association for all outcomes. Further, the non-linear dose-response analysis showed some evidence for non-linearity between poultry consumption and risk for CVD and ACM. Additionally, substituting red and/or processed meat with poultry was inversely associated with the risk for ACM, CVDs, CHD and stroke. The certainty of evidence was rated as very low or low. This meta-analysis suggests that based upon the results from the substitution analyses poultry could be a healthier alternative to red and processed meat.

Nutrigenetic Interactions Might Modulate the Antioxidant and Anti-Inflammatory Status in Mastiha-Supplemented Patients With NAFLD

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease with no therapeutic consensus. Oxidation and inflammation are hallmarks in the progression of this complex disease, which also involves interactions between the genetic background and the environment. Mastiha is a natural nutritional supplement known to possess antioxidant and anti-inflammatory properties. This study investigated how a 6-month Mastiha supplementation (2.1 g/day) could impact the antioxidant and inflammatory status of patients with NAFLD, and whether genetic variants significantly mediate these effects. We recruited 98 patients with obesity (BMI ≥ 30 kg/m²) and NAFLD and randomly allocated them to either the Mastiha or the placebo group for 6 months. The anti-oxidative and inflammatory status was assessed at baseline and post-treatment. Genome-wide genetic data was also obtained from all participants, to investigate gene-by-Mastiha interactions. NAFLD patients with severe obesity (BMI > 35kg/m²) taking the Mastiha had significantly higher total antioxidant status (TAS) compared to the corresponding placebo group (P value=0.008). We did not observe any other significant change in the investigated biomarkers as a result of Mastiha supplementation alone. We identified several novel gene-by-Mastiha interaction associations with levels of cytokines and antioxidant biomarkers. Some of the identified genetic loci are implicated in the pathological pathways of NAFLD, including the lanosterol synthase gene (LSS) associated with glutathione peroxidase activity (Gpx) levels, the mitochondrial pyruvate carrier-1 gene (MPC1) and the sphingolipid transporter-1 gene (SPNS1) associated with hemoglobin levels, the transforming growth factor‐beta‐induced gene (TGFBI) and the micro-RNA 129-1 (MIR129-1) associated with IL-6 and the granzyme B gene (GZMB) associated with IL-10 levels. Within the MAST4HEALTH randomized clinical trial (NCT03135873, www.clinicaltrials.gov) Mastiha supplementation improved the TAS levels among NAFLD patients with severe obesity. We identified several novel genome-wide significant nutrigenetic interactions, influencing the antioxidant and inflammatory status in NAFLD.

Effect of dietary carbohydrate and lipid modification on clinical and anthropometric parameters in nonalcoholic fatty liver disease: a systematic review and meta-analysis

CONTEXT

Nonalcoholic fatty liver disease (NAFLD) is estimated to affect approximately 25% of the adult population, making it one of the most common chronic liver diseases worldwide and a major public health problem. Still, there is no consensus on the most appropriate nutritional intervention for disease treatment.

OBJECTIVE

To systematize and synthesize the results of randomized controlled trials that have evaluated the effect of dietary interventions with different, quantitative, macronutrient compositions on hepatic steatosis attenuation, serum levels of alanine aminotransferase, aspartate aminotransferase, lipid profile, glucose metabolism markers, and anthropometric parameters of adults and the elderly (age ≥ 60 years) with NAFLD.

DATA SOURCES

MEDLINE databases via PubMed, Embase, Science Direct, LILACS, Web of Science, ClinicalTrials.gov, and Cochrane Library were searched. Randomized controlled trials that compared interventions as diets with values ≤ 45% or 20% of the total daily energy intake from carbohydrates or lipids, respectively, compared with dietary reference intakes, were included.

DATA EXTRACTION

Risk of bias was assessed through the Cochrane Collaboration tool. The meta-analysis was only performed to evaluate the effect of carbohydrate-modified diets on the outcome variables. The number of participants and mean values and respective standard deviations of the outcome variables were extracted and used to calculate weighted mean differences and their respective 95%CIs.

RESULTS

The search strategy resulted in 21 146 studies, of which 10 were retained for qualitative analysis and 6 were included in the meta-analysis. From the analysis of 10 studies were identified 8 articles in which low-calorie diets were evaluated and 3 interventions that used an isocaloric diet. Only 3 studies were classified as having low risk of bias.

CONCLUSION

The observed effects on hepatic steatosis, serum alanine aminotransferase and aspartate aminotransferase levels, parameters of lipid and glucose metabolism, and anthropometric variables were mostly related to a hypocaloric diet. The use of reduced macronutrient interventions had no efficacy.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42018088824.

Genetic Variants Associated with Non-Alcoholic Fatty Liver Disease Do Not Associate with Measures of Sub-Clinical Atherosclerosis: Results from the IMPROVE Study

Non-alcoholic fatty liver disease (NAFLD) and atherosclerosis-related cardiovascular diseases (CVD) share common metabolic pathways. We explored the association between three NAFLD-associated single nucleotide polymorphisms (SNPs) rs738409, rs10401969, and rs1260326 with sub-clinical atherosclerosis estimated by the carotid intima-media thickness (c-IMT) and the inter-adventitia common carotid artery diameter (ICCAD) in patients free from clinically overt NAFLD and CVD. The study population is the IMPROVE, a multicenter European study (n = 3711). C-IMT measures and ICCAD were recorded using a standardized protocol. Linear regression with an additive genetic model was used to test for association of the three SNPs with c-IMT and ICCAD. In secondary analyses, the association of the three SNPs with c-IMT and ICCAD was tested after stratification by alanine aminotransferase levels (ALT). No associations were found between rs738409, rs1260326, rs10401969, and c-IMT or ICCAD. Rs738409-G and rs10401969-C were associated with ALT levels (p < 0.001). In patients with ALT levels above 28 U/L (highest quartile), we observed an association between rs10401969-C and c-IMT measures of c-IMT_max and c-IMT_mean-max (p = 0.018 and 0.021, respectively). In conclusion, NAFLD-associated SNPs do not associate with sub-clinical atherosclerosis measures. However, our results suggest a possible mediating function of impaired liver function on atherosclerosis development.

Dietary Intervention Accelerates NASH Resolution Depending on Inflammatory Status with Minor Additive Effects on Hepatic Injury by Vitamin E Supplementation

Despite the lack of effective pharmacotherapy against nonalcoholic steatohepatitis (NASH) and liver fibrosis, vitamin E (vitE) supplementation and lifestyle modifications are recommended for the management of NASH due to promising clinical results. We recently reported a positive effect of supplementation with 800 IU vitE and atorvastatin on NASH resolution in guinea pigs. In the present study, we investigated the effect of high-dose vitE therapy combined with dietary intervention against progressive NASH and advanced fibrosis in the guinea pig model. Sixty-six guinea pigs received either high-fat (HF) or standard guinea pig chow diet (Control) for 25 weeks. Prior to eight weeks of intervention, HF animals were allocated into groups; dietary intervention (Chow) or dietary intervention with 2000 IU/d vitE supplementation (CvitE). Both Chow and CvitE reduced dyslipidemia, hepatic lipid accumulation and liver weight (p < 0.05), while CvitE further decreased hepatocellular ballooning (p < 0.05). Subanalyses of individual responses within intervention groups showed significant correlation between the hepatic hallmarks of NASH and lipid accumulation vs. inflammatory state (p < 0.05). Collectively, our results indicate that individual differences in sensitivity towards intervention and inflammatory status determine the potential beneficial effect of dietary intervention and high-dose vitE supplementation. Moreover, the study suggests that inflammation is a primary target in NASH treatment.