The Genetics of Nonalcoholic Fatty Liver Disease: Role of Diet as a Modifying Factor

The Effectiveness of Mediterranean Diet in Nonalcoholic Fatty Liver Disease Clinical Course: An Intervention Study

Diet is a modifiable key factor targeted in prevention and management of nonalcoholic fatty liver disease (NAFLD). The aim was to study the effect of Mediterranean Diet (MedDiet) on clinical, biochemical, and inflammatory profile in NAFLD patients with simple steatosis. Potential associations of signal transducer and activator of transcription 3 (STAT3) rs2293152 genotype to diet composition and patients' profile were investigated. In this nonrandomized, open-label, 24-week prospective intervention study, 44 untreated NAFLD patients with nonsignificant fibrosis received nutritional counsel to increase adherence to MedDiet. Adherence to MedDiet was estimated with MedDietScore. Furthermore, we genotyped STAT3 rs2293152 single nucleotide polymorphism and performed clinical and inflammatory measurements. In all patients, MedDietScore increased and anthropometric indices improved, whereas liver imaging, liver fibrosis score, blood pressure, fasting glucose, glycated hemoglobin (HbA1c), C-reactive protein (CRP), visfatin, and oxidized low-density lipoprotein levels were also significantly ameliorated compared with baseline (P < .05). No association of STAT3 polymorphism with diet composition was found. Comparisons of mean differences between G- and C-carriers at the end point of the trial showed that only visfatin was significantly associated with the STAT3 genotype (-0.0 ± 4.6 vs. -4.2 ± 3.9, P = .04, respectively). Carrying the G-allele was associated with an increase of the visfatin levels (3.4 ± 1.5 ng/mL, P = .028). Our results show amelioration of clinical, biochemical, and inflammatory biomarkers in NAFLD patients in response to MedDiet. STAT3 rs2293152 G-carriers experienced more beneficial changes at the end of the intervention compared with baseline. An association between visfatin levels and STAT3 genotype has been shown for the first time.

A modified response of NAFLD patients with non-significant fibrosis in nutritional counseling according to GCKR rs1260326

AIM

To investigate the association between GCKR gene and nutritional treatment in NAFLD-related biomarkers.

METHODS

This was an open-label and single-arm clinical trial in 44 overweight or obese adults with NAFLD receiving nutritional counseling for 6 months. Nutritional data, MedDietScore, clinical, biochemical, inflammatory and oxidative stress biomarkers were evaluated before and after intervention. Further, we genotyped GCKR rs1260326 and in T-allele carriers and non-Τ-carriers we assessed associations between the GCKR variant and nutritional counseling related to change in all biomarkers evaluated.

RESULTS

Anthropometric measurements were significantly reduced after the end of the intervention in patients assigned to nutritional counseling. Liver imaging and fibrosis were significantly improved. GCKR rs1260326 T-allele frequency was 46.7%. T-carriers responded better to nutritional counseling regarding fasting blood glucose levels (mean_6-0 change = -4.94 mg/dL (±9.33), p = 0.005), whereas non-T-carriers did not benefit from the intervention regarding glucose. On the other hand, levels of oxLDL decreased in the non-T-carriers group after the intervention, but not in T-carriers.

CONCLUSIONS

Our results show that GCKR rs1260326 T-allele is associated with better response of NAFLD patients to nutritional treatment regarding fasting blood glucose, but not oxLDL levels. Despite this important finding in the field of nutrigenetics, it is tricky to generalize this effect unless larger studies are conducted.

Evaluating -238 G>A Polymorphism Association in TNF-α Gene with Metabolic Parameters and Nutritional Intakes Among the Iranian NAFLD Patients

Different studies have shown that -238 G>A polymorphism in promoter region of tumor necrosis factor alpha (TNF-α) gene is associated with increased risk of non-alcoholic fatty liver disease (NAFLD). The current study investigates the association between metabolic parameters and nutritional intakes with -238 G>A of TNF-α promoter gene polymorphism among the Iranian patients with NAFLD. In this study, 75 patients with NAFLD and 76 individuals as control were enrolled. Dietary intakes were assessed using a semi-quantitative food-frequency questionnaire. Body mass index and waist to hip ratio were calculated. Biochemical assays were measured after 12 h fasting. -238 G>A Polymorphism of TNF-α gene was determined by using sequencing method. We observed no significant difference in frequency of different genotypes of this polymorphism between NAFLD and control groups (P > 0.05). Among biochemical parameters, TAC showed significant decrease in NAFLD patients with GG genotype when compared to controls (P = 0.001). The comparison of macro and micronutrient intakes between groups according to genotypes showed no statistically significant difference (P > 0.05). Although the data were not statistically significant, further studies with larger sample size are needed to determine the effect of dietary compounds in NAFLD.

Major components of metabolic syndrome and nutritional intakes in different genotype of UCP2 -866G/A gene polymorphisms in patients with NAFLD

Background

It has been suggested that dietary modifications in combination with genetic predisposition play an important role in the pathogenesis of NAFLD. In the current study we aimed to investigate the major components of metabolic syndrome in patients with non-alcoholic fatty liver disease (NAFLD) and nutritional intakes according to different genotype of uncoupling protein-2 (UCP2) −866G/A gene polymorphism in these patients.

Methods

In this study 151 participants including 75 patients with NAFLD and 76 healthy individuals were enrolled. Dietary intakes were assessed using a semi-quantitative food-frequency questionnaire. Physical activity was obtained by metabolic equivalent questionnaire. Anthropometric assessments were conducted by a trained researcher and body mass index and waist to hip ratio were calculated. Body composition was measured by bioelectrical impedance analysis and biochemical assays including fasting serum glucose, liver enzymes and lipid profiles were measured. Polymorphisms of −866G/A UCP2 gene was determined using polymerase chain reaction-restriction fragment length polymorphism method.

Results

Serum triglyceride concentrations in 53.3 % of NAFLD patients compared with 35.5 % of control group was more than 150 mg/dl (P = 0.034). A significantly higher prevalence of low serum high density lipoprotein cholesterol concentrations was also observed in female NAFLD patients (P < 0.001). Dietary intakes in NAFLD group were not significantly different compared with control group (P > 0.05). However, according to genotypes patients with AG genotype had significantly higher protein consumption compared with control group (P < 0.05). Significantly higher consumption of dietary iron and copper in NAFLD patients with AG genotype was only observed among patients with NAFLD. However, the comparison of macro and micronutrient intakes in control group sound for stronger differences for AA genotype although these differences did not achieve significant threshold.

Conclusions

A high prevalence of metabolic abnormalities was reported among NAFLD patients. Additionally, among NAFLD group, patients with AG genotype significantly consumed more protein, iron and copper in their usual diet.