Dietary iron and zinc intakes and nonalcoholic fatty liver disease: A meta-analysis

The differences of dietary iron and zinc intakes between patients with nonalcoholic fatty liver disease (NAFLD) and controls remain controversial. The meta-analysis aimed to explore the differences of dietary iron and zinc intakes between NAFLD patients and healthy subjects.

A systematic literature search was performed up to July 2021 in databases of PubMed, Embase, Web of Science, Cochrane Library, Chinese National Knowledge Infrastructure (CNKI), and Wanfang. Using a randomeffects model, the differences of dietary iron and zinc intakes between cases and controls were calculated as standardized mean differences (SMDs) with 95% confidence intervals (CIs). A total of 21 studies from 19 articles with 6639 cases were included.

The pooled estimate showed no difference in dietary iron consumption in the NAFLD groups compared with control groups. The difference became significant in Asia (SMD=0.16; 95% CI: 0.04, 0.28; I2=89.1%; pheterogeneity<0.001) as well as in cross-sectional studies (SMD=0.12; 95% CI: 0.07, 0.17; I2=4.7%; pheterogeneity=0.350). The difference in dietary zinc intake between cases and controls was not significant. We noticed a statistically significant increase of dietary zinc intake in NAFLD compared to controls in studies using food-frequency questionnaire (FFQ) to evaluate dietary intake (SMD=0.15; 95% CI: 0.10, 0.20; I2=12.2%; pheterogeneity=0.332).

Our findings indicated that dietary iron intake in patients with NAFLD was higher than healthy subjects in Asia.