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Background: Zinc deficiency is often associated with nutritional iron deficiency (ID), and may be exacerbated by low selenium status. Aim: To investigate risk of iron and zinc deficiency in women with contrasting selenium status. Methods: In a cross-sectional study, 1-day diet composites and blood samples were collected from self-selected Malawian women aged 18−50 years from low- (Zombwe) (n=60) and high-plant-available soil selenium (Mikalango) (n=60) districts. Diets were analyzed for trace elements and blood for biomarkers. Results: Zinc deficiency (>90 %) was greater than ID anemia (6 %), or ID (5 %), attributed to diets low in zinc (median 5.7 mg/day) with high phytate:zinc molar ratios (20.0), but high in iron (21.0 mg/day) from soil contaminant iron. Zombwe compared to Mikalango women had lower (p<0.05) intakes of selenium (6.5 vs. 55.3 µg/day), zinc (4.8 vs. 6.4 mg/day), iron (16.6 vs. 29.6 mg/day), lower plasma selenium (0.72 vs. 1.60 µmol/L), and higher body iron (5.3 vs. 3.8 mg/kg), although plasma zinc was similar (8.60 vs. 8.87 µmol/L). Body iron and plasma zinc were positive determinants of hemoglobin. Conclusion: Risk of zinc deficiency was higher than ID and was shown not to be associated with selenium status. Plasma zinc was almost as important as body iron as a hemoglobin determinant.

Mineral malnutrition is widespread in sub-Saharan Africa but its extent is difficult to quantify. Using Malawi as a case study, the aim of this work was to investigate the adequacy of calcium (Ca) and magnesium (Mg) nutrition by combining national food supply and food composition data with a new spatial survey of maize grain. Non-maize dietary sources of Ca and Mg were estimated using existing food supply and composition data. Calcium and Mg concentrations in maize grain were determined at 88 field sites, representing > 75 % of Malawi’s land area in terms of soil classification. Median maize grain concentrations from the survey were 34 and 845 mg kg-1, representing a per capita supply of 12 and 299 mg d-1of Ca and Mg, respectively. Combining these data with food supply and composition data reveals that average Ca nutrition is likely to be inadequate for many individuals, whereas average Mg nutrition appears adequate. Optimal supply of Ca per capita depends critically on balanced food availability and choice. Since maize grain sourced from highly calcareous soils is still unlikely to deliver > 5 % of estimated average requirements, agronomic solutions to rectify Ca malnutrition via maize are limited, in comparison with strategies for dietary diversification.