Dietary n-6 to n-3 fatty acid ratio is related to liver fat content independent of genetic effects : Evidence from the monozygotic co-twin control design

Abstract

Background & aim: Lifestyle changes focusing on diet and exercise remain the cornerstone of the treatment of non-alcoholic fatty liver disease (NAFLD). The present co-twin control study of monozygotic (MZ) twin pairs was designed to identify nutritional factors potentially involved in the pathogenesis of NAFLD. Methods: Cross-sectional study of 50 MZ twin pairs (age range: 23-36 years), of which ten pairs were discordant for liver fat (liver fat percentage of one twin 5% and a difference between co-twins of >5%) as determined by magnetic resonance spectroscopy. Nutrient intake was calculated from 3-day food records. Results: Among the ten liver fat-discordant twin pairs, the n-6: n-3 ratio was significantly higher in the twins with higher liver as compared to their co-twins with lower liver fat (6.6:1 vs. 3.2:1, p-value = 0.005). In multiple regression analysis of within-pair differences including all 50 twin pairs, a higher n-6: n-3 ratio was significantly associated with a higher liver fat percentage within MZ twin pairs after adjustment for body mass index, energy intake and other covariates (standardized beta = 0.43, p-value = 0.001). Conclusions: Our findings suggest that the n-6: n-3 ratio is a promising dietary agent for the prevention and treatment of NAFLD. Clinical trials are required to better understand causal relationships and required doses. (C) 2019 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.