Potential role of inflammation in relation to dietary sodium and beta-carotene with non-alcoholic fatty liver disease: a mediation analysis

Background High sodium intake has been linked to the prevalence of non-alcoholic fatty liver disease (NAFLD), but underlying mechanism remains unclear. This study aims to explore the role of chronic inflammation in the association between sodium and NAFLD. We also observed whether beta-carotene, which had a strong anti-inflammatory effect, lowers the odds of NAFLD. Methods We performed mediation analyses to assess the mediating effects of C-reactive protein (CRP) and red cell distribution width (RDW) on the relationship between dietary sodium and NAFLD defined by the hepatic steatosis index (HSI) and the fatty liver index (FLI), respectively. Results A total of 6725 participants were included in this study. Compared with the high sodium-low carotene group, participants in the high sodium-high carotene group had 16% and 26% lower odds for HSI and FLI-defined NAFLD, respectively. There were positive indirect effects of dietary sodium intake on the HSI-defined NAFLD (indirect effect: 0.0057, 95% CI: 0.0021-0.0091, P < 0.0001), as well as the FLI defined NAFLD (indirect effect: 0.0081, 95% CI: 0.0024-0.0162, P < 0.0001) when C-reactive protein (CRP) was considered as a mediator. The mediating effects were somewhat attenuated after further adjusting for dietary beta-carotene intake. Similar results were found when RDW was considered as a mediator in the HSI-defined NAFLD analysis. Conclusions Higher sodium intake increases the odds of NAFLD by upregulating inflammation. Dietary beta-carotene may attenuate this association by down regulating inflammation.