Why Should A Person Eating Three Meals A Day Need An Iron Supplement?

Your body needs iron to produce the oxygen-carrying protein in red blood cells known as hemoglobin. Although you lose very little iron each day, the Institute of Medicine recommends that healthy adult males and post-menopausal females meet the daily recommended intake of 8 mg per day. Research published in the "Nutritional Research Review" states that most people in developed countries consume enough iron, but factors that limit the absorption of iron or increase your need for iron can cause a deficiency that requires iron supplements.

Iron in Food

Food contains two types of iron. Animal foods contain heme iron, named because it is derived from the hemoglobin in the blood. Plant foods and foods fortified with iron contain non-heme iron. Your body absorbs heme iron more effectively than non-heme iron. You can absorb between 15 and 35 percent of the heme iron in foods but only 2 to 20 percent of the non-heme iron in foods. Although you eat three meals per day, if your diet consists mostly of foods that contain non-heme iron, like ready-to-eat breakfast cereals, beans or spinach, you may not meet the daily recommended iron intake.

Calcium Inhibition

Although scientists do not understand the exact mechanism of action, calcium inhibits the absorption of iron. Your body absorbs calcium and iron differently, suggesting that calcium does not inhibit the iron absorption through direct competition for the same receptors in the intestines. Instead, research published in the "Nutritional Research Review" proposes that calcium may interact with food components that affect iron availability or the calcium may affect the receptors that bind to the iron. If your three meals a day include iron-rich foods along with milk or other calcium-rich dairy products, your body may not be absorbing the iron.

Reduced Bioavailability

Other substances naturally found in foods can interfere with iron absorption or decrease the bioavailability of iron, making it unavailable for the body to use. Spinach serves as a source of iron, containing 3.2 mg of iron per 1/2 cup serving of boiled spinach. Spinach also contains a chemical substance known as oxalic acid. Oxalic acid binds to metal ions such as iron, making it unavailable for the body. Another chemical, known as phytic acid, also binds to metal ions like iron. Foods high in phytic acid, like almonds, reduce the amount of available iron in your body. So even if you eat three meals per day, depending on the type of food you eat, your body may not get enough usable iron, increasing your need for supplements.

Increased Need

Many factors can increase your need for iron. Adult women ages 19 to 50 need more iron per day, up to 18 mg per day. The Institute of Medicine recommends this increased intake because women of child-bearing age lose blood, and therefore iron, each month through menstruation. Pregnant women also need more iron, due to the increase in blood volume needed to support the developing baby. Pregnant women should intake 27 mg of iron per day, but ask your doctor about your need for an iron supplement. Patients who suffer from kidney failure and require dialysis may also need an iron supplement to reduce their risk of iron-deficiency anemia. Gastrointestinal disorders that interfere with the absorption of nutrients, like Crohn's disease, also increase your need for supplements. The World Health Organization reports iron deficiency as the most common nutrient deficiency in the world, so if you fear you are at risk, talk with your doctor about your need for iron supplements.