A good place to start for the controversy about how much iron humans need is
a book edited by Patricia Stuart-Macadam and Susan Kent, titled "Diet,
Demography, and Disease: Changing Perspective on Iron Deficiency Anemia."
It was published in the early 1990s, by Aldine de Gruyter.  The gist, in one
sentence, is that current standards for iron levels are set way too high,
and that the level of iron in breast milk is exactly right for humans, and
that too much iron feeds bacteria and viruses.

Kathy Dettwyler