Overweight children have higher circulating hepcidin concentrations and lower iron status but have dietary iron intakes and bioavailability comparable with normal weight children

Background: Obesity increases the risk for iron deficiency, but the underlying mechanism is unclear. It is possible that overweight individuals may have lower dietary iron intake and/or bioavailability. Alternatively, obesity-related inflammation may increase hepcidin concentrations and reduce iron availability. Circulating hepcidin levels have not been compared in normal weight vs overweight individuals. Objective: The objective of this study was to compare iron status, dietary iron intake and bioavailability, as well as circulating levels of hepcidin, leptin and interleukin-6 (IL-6), in overweight vs normal weight children. Design: In 6–14-year-old normal and overweight children (n=121), we measured dietary iron intake, estimated iron bioavailability and determined body mass index s.d. scores (BMI-SDS). In all children (n=121), we measured fasting serum ferritin, soluble transferrin receptor (sTfR), C-reactive protein (CRP) and leptin; in a subsample, we measured IL-6 (n=68) and serum hepcidin (n=30). Results: There were no significant differences in dietary iron intake or bioavailability comparing normal and overweight children. The prevalence of iron-deficient erythropoiesis (an increased sTfR concentration) was significantly higher in the overweight than in the normal weight children (20 vs 6%, P=0.022, with sTfR concentrations of 4.40±0.77 and 3.94±0.88¿mg¿l-1, respectively, P=0.010). Serum hepcidin levels were significantly higher in the overweight children (P=0.001). BMI-SDS significantly correlated with sTfR (P=0.009), serum hepcidin (P=0.005) and the three measures of subclinical inflammation, namely CRP (P