Iron Disorder Metabolism

Iron metabolism is essential for maintaining health and for the production of erythrocytes, or red blood cells. The intestines extract iron from iron rich foods, which is then stored in the body’s cells as the iron compound ferritin.

Too little ferritin leads to anemia, a condition characterized by insufficient levels of red blood cells or hemoglobin. Excessive ferritin leads to an organ-damaging condition known as iron overload.

Red Blood Cells and Ferritin

Iron metabolism is vital to the formation and proper function of red blood cells. Erythrocytes transport oxygen from the lungs to cells throughout the body. To perform this task, red blood cells require ferritin. Ferritin is stored in the red blood cells’ hemoglobin, where it aids in the binding of oxygen molecules.

Iron Metabolism and Recycled Ferritin

The human body excels at iron metabolism, iron regulation and iron storage. The body’s iron regulation processes are so efficient that only a tiny percent of the body’s iron content relies on daily intestinal iron metabolism.

The total iron content in the average adult male is four grams. Only one to two milligrams of the daily iron requirement comes from the metabolism of iron rich foods. Most of the body’s iron content comes from recycled ferritin.

As cells die and are reabsorbed into the body, iron regulation processes redirect ferritin released from dead cells—particularly red blood cells—to the bone marrow. In the bone marrow, recycled iron is made available to growing erythrocytes.

Iron Metabolism and Iron Excretion

The body’s complex system of iron regulation and ferritin recycling ensures that as little iron is excreted as possible. On average, an adult male loses only 0.9 milligrams a day through the intestines, skin cell exfoliation, sweat and urine. Bleeding can also deplete iron reserves.

Women lose more iron than men because of menstrual bleeding and the high iron demands of pregnancy and lactation. Ferritin lost due to menstrual bleeding adds 0.4 milligrams to a woman’s daily iron loss, so women lose 1.3 milligrams for every 0.9 milligrams of iron lost by men. Iron loss due to pregnancy adds yet another four milligrams to this total.

Daily Iron Metabolism Losses

These are the approximate daily losses of iron in healthy individuals:

  • intestinal excretion: 0.6 milligrams
  • sweat and skin cell exfoliation: 0.2 milligrams
  • urine: 0.1 milligrams
  • menstruation: 0.4 milligrams
  • pregnancy or lactation: 4.0 milligrams

Intestinal Iron Metabolism

Homeostasis refers to the body’s ability to maintain internal equilibrium by adjusting its internal processes. Most of the body’s regulatory functions use excretion to maintain homeostasis. Iron regulation is unique among the body’s homeostatic functions. Iron regulation is fulfilled mainly by absorption and metabolism.

An adult male requires ten milligrams a day of dietary iron, which is easily provided by ingesting iron rich foods. Women of childbearing age require fifteen milligrams a day, a demand which can rise as high as thirty milligrams during pregnancy.

Most intestinal iron absorption occurs in the duodenum and jejunum (the first two sections of the small intestine). Iron uptake is tightly controlled to prevent iron overload, so only six to twelve percent of dietary iron is absorbed by the intestines.

Small as it is, the amount of iron absorbed through the intestines is vital to iron regulation. Eating iron rich food is the only way to prevent a slow depletion of stored ferritin. Daily iron requirements vary depending on age and gender.

Daily Iron Requirements

These are general guidelines for daily iron requirements:

  • infants younger than six months: six milligrams
  • six months to ten years: ten milligrams
  • males aged eleven to eighteen: twelve milligrams
  • males aged nineteen and up: ten milligrams
  • females aged eleven to fifty: fifteen milligrams
  • females fifty and over: ten milligrams
  • pregnant women: thirty milligrams
  • breastfeeding women: fifteen milligrams

Iron Rich Foods

Eating iron rich foods ensures that sufficient iron metabolism occurs and daily iron requirements are met. This is especially important for women, whose high levels of iron loss make it difficult to maintain iron levels even when eating iron rich foods.

Iron rich foods include:

  • almonds and brazil nuts
  • asparagus
  • broccoli
  • brown rice
  • collards
  • dandelion greens
  • dried beans and peas
  • dried fruit (prunes, apricots, raisins)
  • egg yolk
  • iron fortified cereals
  • kale
  • lean red meat
  • lima, soy and kidney beans
  • liver
  • oysters
  • poultry
  • salmon
  • spinach
  • tuna
  • wheat, millet and oats.

The body does not absorb iron equally from all iron rich foods. Meat-based iron is generally absorbed more easily than vegetable iron. Iron metabolism can be aided by mixing meat with beans or green leafy vegetables, which increases the absorption of iron from the vegetables. Combining foods high in vitamin C with iron rich foods also increases iron absorption.

Resources

Bridges, K. R. (updated 2001, January 11). Iron absorption.

Heeney, M. M.,