Iron fortification: Flame-made nanostructured Mg- or Ca-doped Fe oxides

Jesper T.N. Knijnenburg, Florentine M. Hilty, Alexandra Teleki, Frank Krumeich, Richard F. Hurrell, Michael B. Zimmermann, SOTIRIS E. PRATSINIS

ETH Zurich, Switzerland

     Abstract Number: 512
     Last modified: May 13, 2010

Abstract
Iron deficiency affects approximately 2 billion people worldwide, especially young women and children. Food fortification with iron is a sustainable approach to alleviate iron deficiency but remains a challenge. Water-soluble compounds with high bioavailability (e.g. the “gold standard” FeSO$_4) usually cause unacceptable sensory changes in foods, while compounds that are less reactive in food matrices are often less bioavailable [1]. Solubility (and therefore bioavailability) can be improved by increasing the specific surface area (SSA) of the compound, i.e. decreasing its particle size to the nm range. Rohner et al. [2] prepared nanostructured FePO$_4 by flame spray pyrolysis (FSP) with SSA as high as 195 m$^2/g (~11 nm) that exhibited high solubility and bioavailability comparable to FeSO$_4 (the “gold standard” as supplement to alleviate iron deficiency) in Sprague-Dawley rats but with improved sensory properties. Recently Hilty et al. developed zinc-containing nanostructured iron compounds with nutritionally attractive Zn-compounds by FSP. The addition of Zn increased iron solubility and (as shown recently) bioavailability that was comparable to FeSO$_4 but with improved sensory (color) properties [3]. Bioavailability was determined in-vivo by actual administration of these fortificants to rats, where no adverse effects in organs and tissues were found. Additional doping of Zn/Fe oxide with Mg increased Fe absorption and improved powder color [3]. Here, iron oxide-based nanostructured compounds with Mg or Ca are made using FSP. Addition of either element increased iron solubility to a level comparable to iron phosphate. Furthermore, these additions lightened the powder color and sensory changes in fruit yoghurt were less prominent than for FeSO$_4.
[1] Hurrell R.F. (2002), Journal of Nutrition, 132, 806S-812S
[2] Rohner F. et al. (2007), Journal of Nutrition, 137, 614-619
[3] Hilty F.M. et al. (2010), Nature Nanotechnology, 5, 374-380