Why Does a Diet High in Iron Decrease the Absorption

Multiple Choice

Why does a diet high in iron decrease the absorption of copper?

A) Copper and iron bind together to form insoluble complexes.
B) Copper depends upon magnesium for transport and iron binds magnesium.
C) Copper is oxidized to its less absorbable cupric form by iron.
D) Copper and iron compete for the same transport proteins.