Iron in the diet of animals is predominantly in the ferric form, but it must be reduced to the ferric form by a specific ferrireductase before it can be transported across the cell membrane into the cell:

To be absorbed, dietary iron… must be in its ferrous Fe2+ form. A ferric reductase enzyme on the enterocytes’ brush border, duodenal cytochrome B (Dcytb), reduces ferric Fe3+ to Fe2+. A protein called divalent metal transporter 1 (DMT1), which can transport several divalent metals across the plasma membrane, then transports iron across the enterocyte’s cell membrane into the cell.


Why is this necessary?


1 Answer 1


This is not my subject, but from scanning the introductions to a couple of reviews on the general topic of iron metabolism, the following factors seem to be important:

  • Ferric iron is less soluble than ferrous iron [1].

  • Ferric iron is potentially toxic in the cell because it can be reduced by oxygen, giving reactive oxygen species which are dangerous to the cell [2].

[1] Srai et al. (2002)

[2] Kaplan (2002)

  • $\begingroup$ @John — Thanks for picking up the typo. $\endgroup$
    – David
    Commented Apr 28, 2023 at 15:50

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