title: Maize grain and soil surveys reveal suboptimal dietary selenium intake is widespread in Malawi.
abstract: Selenium is an essential element in human diets but the risk of suboptimal intake increases where food choices are narrow. Here we show that suboptimal dietary intake (i.e. 20-30 µg Se person(-1) d(-1)) is widespread in Malawi, based on a spatial integration of Se concentrations of maize (Zea mays L.) grain and soil surveys for 88 field sites, representing 10 primary soil types and >75% of the national land area. The median maize grain Se concentration was 0.019 mg kg(-1) (range 0.005-0.533), a mean intake of 6.7 µg Se person(-1) d(-1) from maize flour based on national consumption patterns. Maize grain Se concentration was up to 10-fold higher in crops grown on soils with naturally high pH (>6.5) (Eutric Vertisols). Under these less acidic conditions, Se becomes considerably more available to plants due to the greater solubility of Se((IV)) species and oxidation to Se((VI)).
authors.affiliation: School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, LE12 5RD, UK.
authors.forename: Allan D C
authors.initials: AD
authors.lastname: Chilimba
authors.forename: Scott D
authors.initials: SD
authors.lastname: Young
authors.forename: Colin R
authors.initials: CR
authors.lastname: Black
authors.forename: Katie B
authors.initials: KB
authors.lastname: Rogerson
authors.forename: E Louise
authors.initials: EL
authors.lastname: Ander
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Watts
authors.forename: Joachim
authors.initials: J
authors.lastname: Lammel
authors.forename: Martin R
authors.initials: MR
authors.lastname: Broadley
mesh_terms: D004032:Diet; D004781:Environmental Exposure; D006801:Humans; D008295:Malawi; D012643:Selenium / Q000008:administration & dosage / Q000172:deficiency*; D012987:Soil / Q000737:chemistry*; D003313:Zea mays / Q000737:chemistry*
chemical_list: D012987:Soil; D012643:Selenium