Many things can cause iron deficiency & most fall into 2 main categories--blood loss & decreased iron intake.
Ex's of the former include GI (intestine) bleeding & women's menstrual cycles (though many women are not iron deficient). Ex's of the latter include poor diet & impaired absorption. A healthy diet & limiting causes of GI bleeding (alcohol, nsaids like ibuprofen, naproxen) can help prevent.
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