Who will get the most benefit from an iron supplement

With no choices to choose from. I would say someone with anemia

Those that would require more blood cells. Those people who have a tendency to be anemic, and have low blood cell counts or require a greater blood flow. Those who are naturally anemic, hemophiliacs who are suceptivle to bleeds (and thus can loose greater quantities of blood due to the inability to clot. Additionally patients who are pregnant actually end up with a higher volume of blood then most normal humans, but require iron to keep up with this increased volume. Women with heavy menses also (or most women) are recommended to consume additional iron to supplement blood that is lost.