Iron

This fact sheet is one in a series containing information to help you select foods that provide adequate daily amounts of vitamins, minerals and dietary fiber. Following these guidelines will put your diet in accordance with the Dietary Guidelines for Americans, which focuses on nine general topics:

Why Do We Need Iron?

Iron, a mineral, functions primarily as a carrier of oxygen in the body, both as a part of hemoglobin in the blood and of myoglobin in the muscles. It also aids in immune function, cognitive development, temperature regulation, energy metabolism and work performance. About 90 percent of the iron in the body is conserved and reused every day; the rest is excreted. Men are able to naturally store more iron than women. In order to maintain iron balance in the body for both men and women, dietary iron must supply enough iron to meet the 10 percent gap that the body has excreted or else deficiency will result.

How Much Iron Do We Need?

The amount of iron you need each day depends on your age and gender. Average daily needs are listed in milligrams (mg) in the following chart.

How Can We Get Enough Iron?

Eating a variety of foods that contain iron is the best way to get an adequate amount. Healthy individuals who eat a balanced diet rarely need supplements. Many doctors recommend feeding a fortified milk formula or breakfast cereal, or giving an iron supplement to infants and toddlers, because it is especially difficult to meet their iron needs. Doctors usually prescribe iron supplements for pregnant or lactating women. For vegetarians or vegans, it is important to consume sufficient amounts of moderately rich iron foods such as beans, legumes and fortified breads, cereals and flours. Soy products are typically good sources of iron as well. The list of foods in the table below will help you select those that are good sources of iron.

The ability of the body to absorb and utilize iron from different foods varies. The iron in meat, poultry and fish is absorbed and utilized more readily than iron in other foods. The presence of these animal products in a meal increases the availability of iron from other foods. The body increases or decreases iron absorption according to need. The body absorbs iron more efficiently when iron stores are low and during growth spurts or pregnancy. The presence of vitamin C (ascorbic acid) in a meal also increases iron absorption. Tea, coffee or red wine, or an excess of zinc, manganese or calcium can decrease iron absorption.

What Are Good Sources of Iron?

Dietary sources of iron are found in two forms: heme iron and nonheme iron. Heme sources are provided by animal products (meats) and are readily absorbed. Approximately 40 percent of iron found in meat is heme, with the best sources being liver, seafood, fish, lean meat and poultry. Nonheme iron is provided from plant sources. It is less efficiently absorbed, and its absorption amount depends upon the body's needs (if there are low stores, more iron will be absorbed and vice versa). Nonheme sources that are high in iron include cooked spinach, tofu, beans, eggs, nuts, whole grains and fortified grain products.

Good sources of iron can be found in the protein, grains, fruits and vegetables groups on MyPlate. The table below contains foods with high levels of iron.

What About Enriched or Fortified Foods?

Pasta, white rice and most breads made from refined flours are enriched with iron, because iron is one of the nutrients lost in processing. Other nutrients added to refined flours and pasta include thiamin, niacin and riboflavin. Enriched products or products made from enriched flour are labeled as such. Minimum and maximum enrichment levels are specified for thiamin, riboflavin and niacin, but only a minimum level of iron is required in farina. Thus, iron enrichment levels for farina vary from brand to brand. Most ready-to-eat and instant-prepared cereals are fortified with iron. Fortified, ready-to-eat cereals usually contain at least 25 percent to 30 percent of the U.S. RDA for iron. Since cereals vary, check the label on the package for the percentage of the U.S. RDA for a specific cereal.

What If I Don't Get Enough Iron?

The most common indication of an iron deficiency is iron deficiency anemia, a condition in which the size and number of red blood cells are reduced. This condition can result from inadequate intake of iron or from blood loss. Anemia results in decreased oxygen in the blood, and can cause tiredness, headaches, irritability and/or depression. Anemia can also be caused by heavy blood loss through heavy menses, ulcers, hemorrhoids and colon cancer. Toxicity can occur if too much iron is absorbed, but this is rare.

How to Prepare Foods to Retain Iron

Iron skillets used for cooking can add to the total iron intake of the food being cooked in them, especially when acidic foods are cooked (such as tomato sauce). However, iron can be lost using other cooking methods, even under the best conditions. To retain iron do the following:

• Cook foods in a minimal amount of water.
• Cook foods for the shortest possible time.

References

Duyff, Roberta. American Dietetic Association: Complete Food and Nutrition Guide. 4th ed. Hoboken, NJ: John Wiley and Sons, 2012.

Escott-Stump, Mahan. Krause's Food, Nutrition, and Diet Therapy. 13th ed. Philadelphia, PA: W. B. Sanders, 2011.

Gerrier, S., and L. Bente. Panel on Micronutrients, Subcommittees on Upper Reference Intakes of Nutrients and of Interpretation and the Uses of Dietary Reference Intakes, and the Standing Committee on the Scientific Evaluation of Dietary Reference Intakes. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington, DC: National Academies Press, 2001.

USDA and U.S. Department of Health and Human Services. Dietary Guidelines for Americans. 7th ed. Washington, DC: U.S. Government Printing Office, 2010.

Reviewed by: Barbara Hennard, MA, Extension Educator, Family and Consumer Sciences, Ohio State University Extension