Effectiveness of dietary interventions on cardio-metabolic risk factors in patients with nonalcoholic fatty liver disease: a systematic review and meta-analysis of randomized controlled trials

Background Dietary modification is considered as one of the main strategies in the management of nonalcoholic fatty liver disease (NAFLD). The objective of this study was to systematically investigate the effect of dietary interventions on the cardio-metabolic risk factors, including lipid profile and insulin resistance in this population. Methods We searched electronic databases of PubMed and Scopus until January 2020 and included randomized controlled trials that compared the effect of dietary modifications vs. control on lipid profile and insulin resistance in patients with NAFLD. The random-effect analysis was performed to calculate pooled weighted mean differences (WMD). Results Our finding showed that serum triglycerides (TG) (n=5, WMD -38.50 mg/dL, 95% confidence interval [CI] -61.68 to -15.31; P=0.001) and total cholesterol (TC) (n=4, WMD -18.70 mg/dL, 95%CI -34.85 to -2.53; P=0.023) decrease following diet intervention along with marginally significant weight reduction (n=5, WMD -3.61 mg/dL, 95%CI -7.25 to 0.04; P=0.053). There was no change in the homeostatic model assessment for insulin resistance, high- and low-density lipoprotein (LDL) levels (P>0.05). Subgroup analysis revealed that Mediterranean diet reduced TG (n=2, WMD -57.52 mg/dL, 95%CI -75.73 to -39.31; P<0.001) and weight (n=2, WMD -7.59 Kg, 95%CI -13.53 to -1.66; P=0.012), and also increased LDL level (n=2, WMD 29.73 mg/dL, 95%CI 13.82-45.65; P<0.001). However, standard hypocaloric diet improved TC (n=2, WMD -23.20 mg/dL, 95%CI -36.96 to -9.44; P=0.001) and LDL (n=2, WMD -16.82 mg/dL, 95%CI -29.44 to -4.19; P=0.009). Conclusion Dietary modifications may improve serum TG, TC, and obesity in NAFLD.