Iron deficiency anemia is most commonly caused by which of the following?

Iron deficiency anemia occurs when the body does not have enough iron to produce hemoglobin, the protein in red blood cells that carries oxygen. The most common cause of iron deficiency anemia is a lack of iron in the diet. This can occur for various reasons, such as insufficient dietary intake, malabsorption of iron due to gastrointestinal conditions, or increased iron needs during periods of growth or certain life stages, like pregnancy.

Inadequate dietary iron leads to decreased hemoglobin production, resulting in anemia. Iron-rich foods include red meat, poultry, fish, lentils, beans, and fortified cereals. When an individual does not consume enough of these foods, they can develop a deficiency, leading to the symptoms associated with iron deficiency anemia, such as fatigue, weakness, and pallor.

The other options do not directly contribute to the development of iron deficiency anemia. Lack of dietary copper, excessive exercise, and increased calcium levels are not recognized as common causes of this specific type of anemia. Instead, they may be associated with other conditions or health concerns, but they do not directly lead to a deficiency of iron necessary for hemoglobin production.