Four groups of people have a greater-than-normal need for iron: infants, growing boys and girls, women who are menstruating, and pregnant women. Infants often lack iron because they drink primarily milk, and milk contains no iron. Growing boys and girls often don't get enough iron in their daily diet to keep up with their developing bodies. Menstruating women need extra iron because of the blood they lose during menstruation. And pregnant women lack sufficient iron because of the blood needed by their growing fetus.

These conditions are recognized in the U.S. government's Recommended Dietary Allowances (RDAs). An RDA is the amount of a vitamin or mineral that a person needs to take in each day in order to stay healthy. The RDA for iron for infants one year of age is 15 mg (milligrams) per day. This number drops to 10 mg a day for boys and girls between the ages of three and eleven. During the teen years, however, the RDA for iron increases to 18 mg per day.

That standard stays the same for women until they reach menopause (the period when menstruation stops). It then drops to 10 mg per day again. For pregnant women, however, the RDA ranges from 30 to 60 mg per day. It is during this period that the human body needs iron more than any other time in life.

Most people can get all the iron they need by choosing the right foods. Beef, kidney, liver, beans, clams, peaches, and soybeans are all rich in iron. But pregnant women find it nearly impossible to get enough iron from their diet. They usually have to take iron pills in order to avoid anemia.