Association of leisure sedentary behavior and physical activity with the risk of nonalcoholic fatty liver disease: a two-sample Mendelian randomization study

Abstract

IntroductionPrevious observational studies have demonstrated the relationship between leisure sedentary behavior, physical activity, and nonalcoholic liver disease (NAFLD). However, whether these associations are causal or confounding factors remains unclear.MethodsPooled genetic data from the UK Biobank and other large genome-wide association studies (GWAS) were used to extract instrumental variables representing sedentary television watching, computer use, driving, vigorous physical activity (VPA), and moderate-to-vigorous physical activity (MVPA). The two-sample Mendelian randomization (MR) method was used to explain the causal relationship between them and NAFLD. The inverse variance of the weighted method was used as the main analysis method, and MR-Egger, weighted median, MR-PRESSO, and other supplementary methods were also used. A sensitivity analysis was also performed. Simultaneously, the common risk factors for NAFLD were further analyzed for potential mediating associations.ResultsWe observed that sedentary television viewing (odds ratio (OR): 1.84; 95% confidence interval (CI): 1.09–3.10; p = 0.021) and genetically predicted VPA duration (OR: 0.0033; 95% CI: 0.000015–0.70; p = 0.036) were suggestively associated with the risk of NAFLD. Using a computer (OR: 1.51; 95% CI: 0.47–4.81; p = 0.484), driving (OR: 0.78; 95% CI: 0.05–11.94; p = 0.858), and MVPA time (OR: 0.168; 95% CI: 0.01–2.81; p = 0.214) were not significantly associated with NAFLD. The role of heterogeneity versus pleiotropy was limited in all the analyses.DiscussionThis study supports the association between sedentary television watching and an increased risk of NAFLD, along with vigorous physical activity as a possible protective factor for NAFLD.

Aerobic and Muscle-Strengthening Physical Activity, Television Viewing, and Nonalcoholic Fatty Liver Disease: The CARDIA Study

“…Our findings are in line with previous human trials [10][11][12][14][15][16][17][42][43][44][45] and epidemiological evidence [21,[46][47][48][49][50], suggesting that replacing sedentary time with aerobic and/or muscle-strengthening physical activity leads to attenuation of intrahepatic lipid deposition. Two studies specifically examined the associations of television viewing with the risk of NAFLD while accounting for physical activity and observed a dose-dependent increased risk of NAFLD with sedentary television viewing [51,52]. However, these studies only examined general leisure-and occupational-domain physical activities and did not examine the independent and additive role of muscle-strengthening physical activity-a physical activity modality that may provide various cardiometabolic health benefits independent of aerobic activity.…”