Two kinds of Iron The human body needs iron to produce hemoglobin, a substance that helps red blood
cells transport oxygen. Without enough iron, a person may feel tired and weak. Dietary
sources of iron include plant sources, such as vegetables and beans, and animal foods,
including poultry, red meat, and fish. However, plant and animal sources are not equal.
The iron in plants, called nonheme iron, is not easily absorbed by the human digestive
system. For example, a half cup of cooked spinach contains a healthy dose of over three
milligrams of iron. Unfortunately, only five percent of that iron can be used by the body.
On the other hand, the iron in animal foods, called heme iron, is better utilized. Heme
iron is contained within a ring of protein, which helps the body to absorb it easily.
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