Iron Fortification: Flame-Made Nanostructured Mg- or Ca-Doped Fe Oxides

 

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” FeSO₄) 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 FePO₄ by flame spray pyrolysis (FSP) with SSA as high as 195 m²/g (~11 nm) that exhibited high solubility and bioavailability comparable to FeSO₄ (the “gold standard” as supplement to alleviate iron deficiency) in Sprague-Dawley rats but with improved sensory properties. Recently Hilty et al. [3] 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 FeSO₄ but with improved sensory (color) properties [4]. 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 [4]. Here, iron oxide-based nanostructured compounds with Mg or Ca are made using FSP [5]. 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 FeSO₄.

[1]  Hurrell RF. Fortification: Overcoming technical and practical barriers, Journal of Nutrition (2002), 132, 806S-812S.

[2]  Rohner F, Ernst FO, Arnold M, Hilbe M, Biebinger R, Ehrensperger F, Pratsinis SE, Langhans W, Hurrell RF & Zimmermann MB. Synthesis, characterization, and bioavailability in rats of ferric phosphate nanoparticles, Journal of Nutrition (2007), 137, 614-619.

[3] Hilty FM, Teleki A, Krumeich F, Buchel R, Hurrell RF, Pratsinis SE & Zimmermann MB. Development and optimization of iron- and zinc-containing nanostructured powders for nutritional applications, Nanotechnology (2009), 20, 475101.

[4]  Hilty FM, Arnold M, Hilbe M, Teleki A, Knijnenburg JTN, Ehrensperger F, Hurrell RF, Pratsinis SE, Langhans W & Zimmermann MB. Iron from nanocompounds containing iron and zinc is highly bioavailable in rats without tissue accumulation, Nature Nanotechnology (2010), published online Apr 25, http://dx.doi.org/10.1038/nnano.2010.79.

[5] Hilty FM, Knijnenburg JTN, Teleki A, Krumeich F, Hurrell RF, Pratsinis SE & Zimmermann MB. Addition of Mg and Ca to nanostructured Fe₂O₃ improves solubility in dilute acid and sensory characteristics in food, Journal of Food Science (2010), submitted.