Increased total iron and zinc intake and lower heme iron intake reduce the risk of esophageal cancer: A dose-response meta-analysis.

Several epidemiological studies investigated the relationship between dietary intake of essential trace elements and the risk of esophageal cancer (EC), yielding inconsistent results. We therefore conducted a systematic meta-analysis to investigate and quantify the putative association between the intake of various essential trace elements and the risk of EC. We searched Embase, PubMed, and Web of Science for eligible articles published through April 2018 reporting the odds ratio (OR) with 95% confidence interval (95% CI). Pooled results were then calculated using fixed and random effect models. A total of 20 articles containing 4855 cases from 1 387 482 participants were included in our analysis. We found a significant inverse correlation between total iron intake and the risk of EC (OR = 0.81, 95% CI: 0.70-0.94), particularly in Asian populations. A dose-response analysis revealed that each 5 mg/day increase in total iron intake was associated with a 15% reduction in EC risk (OR = 0.85, 95% CI: 0.79-0.92). In contrast, each 1 mg/day increase in heme iron intake was associated with a 21% increase in EC risk (OR = 1.21, 95% CI: 1.02-1.45). Lastly, a pooled risk estimate revealed that each 5 mg/day increase in zinc intake was associated with a 15% reduction in EC risk (OR = 0.85, 95% CI: 0.77-0.93). Taken together, our analysis indicates that increased dietary intake of total iron and zinc, as well as decreased heme iron intake, may be associated with a lower risk of developing esophageal cancer. These findings have important public health implications with respect to preventing this relatively common form of cancer.