Different situation, happens to involve iron.

About 12 years ago I was training to go to altitude, and upon the suggestion of a real climber I started taking an iron supplement. After all, he explained, more red blood cells means more hemoglobin, and hemoglobin needs iron. Made sense to me that I would need additional iron.

Elementary. Well, not elementary iron, but some soluable form.

Took the iron, got very ill. Felt like the flu.

At the same time, home from work, sick, I was rooting around the internet. Found an article which described my situation exactly.

Seems the human body regulates some critters in the alimentary tract by adjusting the level of iron available to them. We need some of those critters, but too many will make one ill. Feels lile influenza.

I had overridden my body's defences, and these guys ran wild.

Arf