Not necessary. Contrary to what you might have heard on tv or some "experts", you don't necessarily get iron deficient just because you're vegetarian. Lots of vegetables, beans, & fortified bread are loaded with iron. Many cultures survived millennia on little to no meat & many others with almost no red meat. It depends on the variety of your diet & medical conditions present. Plus there's iron in eggs & fish.
Hopefully never. Humans have no way of getting iron out of our systems except blood loss; we regulate iron by how much we absorb in our small bowel. If someone is not losing a significant amount of blood (we all lose a little) legumes, broccoli and kale should enable a vegetarian to remain adequately iron saturated. We absorb iron slowly, but store it very well, allowing most to go years even without fe absorption.
Man or woman? Female vegetarians would tend to lose iron more quickly and become anemic due to monthly menstrual losses. Pregnancy and breastfeeding also lead to iron loss. "heme" sources of iron (animal iron) are more readily digested than "non-heme" iron found in grains and vegetables, but vegetarians can get enough iron in a diet to maintain health. More info: http://1.Usa.Gov/9mbfej. Read more...