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Iron from nanocompounds containing iron and zinc is highly bioavailable in rats without tissue accumulation

Nature Nanotechnology volume 5, pages 374–380 (2010)Cite this article

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Abstract

Effective iron fortification of foods is difficult, because water-soluble compounds that are well absorbed, such as ferrous sulphate (FeSO4), often cause unacceptable changes in the colour or taste of foods. Poorly water-soluble compounds, on the other hand, cause fewer sensory changes, but are not well absorbed. Here, we show that poorly water-soluble nanosized Fe and Fe/Zn compounds (specific surface area ∼190 m2 g−1) made by scalable flame aerosol technology have in vivo iron bioavailability in rats comparable to FeSO4 and cause less colour change in reactive food matrices than conventional iron fortificants. The addition of Zn to FePO4 and Mg to Fe/Zn oxide increases Fe absorption from the compounds, and doping with Mg also improves their colour. After feeding rats with nanostructured iron-containing compounds, no stainable Fe was detected in their gut wall, gut-associated lymphatics or other tissues, suggesting no adverse effects. Nanosizing of poorly water-soluble Fe compounds sharply increases their absorption and nutritional value.

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Figure 1: Transmission electron microscopy images with SAED patterns (insets) of flame-made, nanostructured food fortificants.
Figure 2: Schematic of the protocol of iron repletion with nanostructured compounds in rats.
Figure 3: Impact of different Fe-containing compounds on changes in haemoglobin concentration and their relative bioavailability compared to FeSO4.
Figure 4: Sensory performance of nanostructured iron-containing compounds in comparison with commercially available FeSO4, NaFeEDTA, ferrous fumarate and electrolytic iron in chocolate and banana milk, two sensitive food matrices at 10 mg Fe per 100 g food.

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Acknowledgements

The authors would like to thank L. Berger (ETH, Zurich) for her technical assistance, M. Haldimann (The Ministry of Health, Bern, Switzerland) for the ICP-MS measurements, F. Krumeich (Electron Microscopy Center ETH, Zurich) for the TEM images of the Fe powders, and L. Molinari (Children's Hospital, Zurich) for support in statistical analysis. We thank P. Lohmann GmbH (Emmerthal, Germany) for providing the FeSO4 for the study at no cost, and BHA Technologies (Muemliswil, Switzerland) for supplying the Teflon filters at no cost. The study was supported by the Swiss National Science Foundation, Bern, Switzerland; the Swiss Commission for Technology and Innovation (KTI Projekt 9765.1 PFLS-LS), Bern, Switzerland; IMP (Industrial Metal Powders (India) Pvt Ltd) and ETH Zurich, Switzerland.

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Authors and Affiliations

  1. Human Nutrition Laboratory, Institute of Food, Nutrition and Health, ETH Zurich, Schmelzbergstrasse 7, Zürich, LFV E19, 8092, Switzerland

    Florentine M. Hilty, Richard F. Hurrell & Michael B. Zimmermann

  2. Physiology and Behaviour Laboratory, Institute of Food, Nutrition and Health, ETH Zurich, Schorenstrasse 16, Schwerzenbach, 8603, Switzerland

    Myrtha Arnold & Wolfgang Langhans

  3. Institute of Veterinary Pathology, Vetsuisse Faculty, University of Zurich, Switzerland

    Monika Hilbe & Felix Ehrensperger

  4. Department of Mechanical and Process Engineering, Particle Technology Laboratory, ETH Zurich, Sonneggstrasse 3, Zürich, 8092, Switzerland

    Alexandra Teleki, Jesper T. N. Knijnenburg & Sotiris E. Pratsinis

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  1. Florentine M. Hilty
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Contributions

F.M.H., M.B.Z., R.F.H. and S.E.P. conceived the experiments. F.M.H., M.B.Z. and W.L. designed the experiments. F.M.H. produced the compounds tested in the rat study. J.T.N.K. produced Mg containing oxides without Zn. F.M.H. and M.A. performed the animal study. M.H. and F.E. performed the histological analysis. F.M.H., A.T. and M.H. analysed the data. F.M.H., A.T., R.F.H. S.E.P., W.L. and M.B.Z. co-wrote the paper.

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Correspondence to Michael B. Zimmermann.

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Hilty, F., Arnold, M., Hilbe, M. et al. Iron from nanocompounds containing iron and zinc is highly bioavailable in rats without tissue accumulation. Nature Nanotech 5, 374–380 (2010). https://doi.org/10.1038/nnano.2010.79

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