Circulating free iron is lethal. Humans have two circulating iron bind
ing proteins to soak up free iron to prevent it from generating toxic
quantities of free radicals. These proteins are transferrin, a high-af
finity, low-capacity protein (2 atoms of iron per molecule of transfer
rin) for which there are receptors on the surface of every iron-requir
ing cell; and ferritin, a lower-affinity, high-capacity protein (maxim
um of 4500 atoms of iron per molecule of ferritin) for which there are
receptors only on the surface of iron-storage cells such as RE (retic
ulo-endothelial) cells. Iron is trapped inside the ferritin protein sh
ell as harmless Fe-3. When there is a high serum level of reduced asco
rbic acid, it drives through the pores of the ferritin protein shell t
o the inside surface, where it converts the Fe-3 to catalytic Fe-2, wh
ich then leaks out of the pores of the ferritin protein shell and gene
rates billions of free radicals. In normal individuals, per milliliter
of serum, there are approximately 300,000 molecules of transferrin pe
r molecule of ferritin. Ferritin protein is an acute phase reactant th
at sharply rises in the presence of inflammation of any kind, whereas
transferrin is a reverse acute phase reactant that falls in the presen
ce of inflammation of any kind.