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The concentration of iron in Zanzibari geophagic earth is high but its in vitro bioavailability is low and it inhibits the bioavailability of dietary iron in an in vitro digestion/Caco‐2 Cell model
Author(s) -
Seim Gretchen,
Ahn Cedric,
Bodis Mary,
Tako Elad,
Miller Dennis,
Glahn Raymond,
Young Sera
Publication year - 2012
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.26.1_supplement.lb282
Subject(s) - bioavailability , chemistry , ferritin , absorption (acoustics) , digestion (alchemy) , dietary iron , iron deficiency , caco 2 , food science , in vitro , environmental chemistry , biochemistry , chromatography , pharmacology , medicine , biology , materials science , anemia , composite material
Geophagy, the deliberate consumption of earth, is strongly associated with Fe deficiency. Two competing hypotheses have been proposed: 1. Geophagy is a means to increase Fe status, 2. Geophagy causes Fe deficiency by inhibiting Fe absorption. Our objective was to test these using 11 geophagic earths consumed in Zanzibar, Tanzania. Fe concentrations were measured with inductively coupled plasma atomic emission spectroscopy. Fe bioavailability from earth, cooked white beans (WB), and a mixture of WB and earth (16:1 ratio) were assessed using an in vitro digestion/Caco‐2 cell model. Ferritin formation was used as an index of iron bioavailability. Median Fe concentration of the earth was 3325.7 (IQR 2439.0, 9041.3) μg/g; all were significantly higher (p<0.05, one tail) than the Fe concentration of WB (76 μg/g). Ferritin formation in cells exposed to earth was lower than in cells exposed to WB, and iron uptake responses of 9 of the 11 earth samples were not significantly different (p<0.05, two tail) from the blank, indicating no bioavailable iron. In cells with WB and earth, 4 of 11 samples had mean ferritin levels that were significantly lower (p<0.05, one tail) than the WB alone, indicating an inhibition of Fe bioavailability. In summary, although geophagic earths are high in total Fe, this Fe is not bioavailable. Further, some earth samples inhibit Fe absorption from foods. In vivo research is now warranted to confirm these observations.