Final answer:
Colon polyps/carcinoma are the most common cause of iron deficiency in the elderly in the Western world. Iron deficiency anemia happens when there is not enough iron to produce sufficient heme.
Step-by-step explanation:
The most common cause of iron deficiency in the elderly in the Western world is colon polyps/carcinoma. Iron deficiency anemia occurs when there is insufficient iron to produce enough heme. This can be caused by a deficiency of iron in the diet, as well as an inability to absorb and transport iron or slow, chronic bleeding.