Systematic review and meta-analysis of controlled intervention studies on the effectiveness of long-chain omega-3 fatty acids in patients with nonalcoholic fatty liver disease

CONTEXT: Treatment options for nonalcoholic fatty liver disease (NAFLD) are needed. OBJECTIVE: The aim of this review was to systematically assess the effects of omega-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFAs), particularly eicosapentaenoic acid and docosahexaenoic acid, on liver-related and metabolic outcomes in adult and pediatric patients with NAFLD. DATA SOURCES: The online information service ProQuest Dialog was used to search 8 literature databases. STUDY SELECTION: Controlled intervention studies in which the independent effects of n-3 LC-PUFAs could be isolated were eligible for inclusion. DATA EXTRACTION: The 18 unique studies that met the criteria for inclusion were divided into 2 sets, and data transcriptions and study quality assessments were conducted in duplicate. Each effect size was expressed as the weighted mean difference and 95%CI, using a random-effects model and the inverse of the variance as a weighting factor. RESULTS: Based on the meta-analyses, supplementation with n-3 LC-PUFAs resulted in statistically significant improvements in 6 of 13 metabolic risk factors, in levels of 2 of 3 liver enzymes, in liver fat content (assessed via magnetic resonance imaging/spectroscopy), and in steatosis score (assessed via ultrasonography). Histological measures of disease [which were assessed only in patients with nonalcoholic steatohepatitis (NASH)] were unaffected by n-3 LC-PUFA supplementation. CONCLUSIONS: Omega-3 LC-PUFAs are useful in the dietary management of patients with NAFLD. Additional trials are needed to better understand the effects of n-3 LC-PUFAs on histological outcomes in patients with NASH. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42017055951.