Well - ecoli do of course feed of iron as is commonly known. This is most obvious in machine shops actually where they have overgrowths of the bacteria in the cooling fluid with iron shavings and in the air I should say. When they (the machine operators)
open the doors and the mist sprays up the bacteria can become airborne.
But the real reason (or the traditional medical reason) for iron deficiency and anemia in inflammatory bowel disease is that Hepcidin (a hormone) mediates iron uptake and release. Sort of the "keep iron levels in check hormone".
Macrophages store Iron - and during certain infections and inflammatory conditions they even become super "Iron Hogs" eating it up and holding onto it like there's no tomorrow. This is why people tend to think, and is has been proposed, that they do it to prevent/deprive iron feeding bacteria of a required nutrient and therefor lesson the bacteria's ability to survive. Although interesting, this has never actually been proven.
It's also been proposed (by real scientists) haha, that Folate can become sequestered during infection and perhaps for the very same process - to deprive certain bacteria of this necessary nutrient. During infection macrophages also tend to increase expression of folate receptors and uptake of folate. But again this has never been proved.
Both are ummm alternative suggestions or ideas that have been explored.
What is known, and is most likely the probable explanation is three things 1) excess iron can lead to free radical production so it's tightly regulated 2) Hepcidin (the hormone mentioned above) is increased by inflammatory cytokines which we hear all about
in IBD and this then reduces the amount of "available" iron during the inflammatory processes.
Increased iron levels will upregulate hepcidin which then in turn decreases iron - and vice versa.
The Inflammatory response or "Inflammation itself" is the cause of iron deficiency (or useful Iron) because iron is no longer released from macrophages - The reason Macrophages hog and eat up all the available Iron is that they use it (Iron) to create oxidative bursts to kill bacteria/Viruses and so on that they phagocytize (eat).
Because macrophages are "hogging" this then leads or contributes highly to the anemia type states associated with inflammatory bowel disease.
Just stuff from my text book.
EDIT: So the bottom line is you'll find the worse the inflammation or "flare" is the lower the iron levels tend to be - all a result of the inflammatory response itself.
Post Edited (Canada Mark) : 6/10/2014 5:19:28 PM (GMT-6)