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Open AccessArticle

Mechanisms of Iron Uptake from Ferric Phosphate Nanoparticles in Human Intestinal Caco-2 Cells

1
Norwich Medical School, University of East Anglia, Norwich, Norfolk NR4 7UQ, UK
2
School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
3
Diabetes and Nutritional Sciences Division, King’s College London, London SE1 9NH, UK
4
Institute of Food, Nutrition, and Health, ETH, Schmelzbergstrasse 9, 8092 Zürich, Switzerland
*
Author to whom correspondence should be addressed.
Nutrients 2017, 9(4), 359; https://doi.org/10.3390/nu9040359
Received: 27 January 2017 / Revised: 27 March 2017 / Accepted: 30 March 2017 / Published: 4 April 2017
Food fortification programs to reduce iron deficiency anemia require bioavailable forms of iron that do not cause adverse organoleptic effects. Rodent studies show that nano-sized ferric phosphate (NP-FePO4) is as bioavailable as ferrous sulfate, but there is controversy over the mechanism of absorption. We undertook in vitro studies to examine this using a Caco-2 cell model and simulated gastrointestinal (GI) digestion. Supernatant iron concentrations increased inversely with pH, and iron uptake into Caco-2 cells was 2–3 fold higher when NP-FePO4 was digested at pH 1 compared to pH 2. The size and distribution of NP-FePO4 particles during GI digestion was examined using transmission electron microscopy. The d50 of the particle distribution was 413 nm. Using disc centrifugal sedimentation, a high degree of agglomeration in NP-FePO4 following simulated GI digestion was observed, with only 20% of the particles ≤1000 nm. In Caco-2 cells, divalent metal transporter-1 (DMT1) and endocytosis inhibitors demonstrated that NP-FePO4 was mainly absorbed via DMT1. Small particles may be absorbed by clathrin-mediated endocytosis and micropinocytosis. These findings should be considered when assessing the potential of iron nanoparticles for food fortification. View Full-Text
Keywords: nano iron; NP-FePO4; bioavailability; Caco-2 cells; simulated gastrointestinal digestion; DMT1; endocytosis nano iron; NP-FePO4; bioavailability; Caco-2 cells; simulated gastrointestinal digestion; DMT1; endocytosis
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Perfecto, A.; Elgy, C.; Valsami-Jones, E.; Sharp, P.; Hilty, F.; Fairweather-Tait, S. Mechanisms of Iron Uptake from Ferric Phosphate Nanoparticles in Human Intestinal Caco-2 Cells. Nutrients 2017, 9, 359.

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