The Importance of Dietary Iron
Iron is found in every cell of your body and is an essential component of hemoglobin, the protein in red blood cells that carries oxygen to tissues throughout the body. Iron is also found in myoglobin, which distributes oxygen to the muscle, skeletal, and heart muscles. Iron is also critical to the proper functioning of the immune system and the production of energy. Insufficient iron stores in the body can lead to anemia and other illnesses. Women who are menstruating, pregnant, or lactating are at an increased risk for iron deficiency.
There are two types of dietary iron: heme iron, which is found only in animal tissue, and non-heme iron, which is found in plant foods and diary products and is added to iron-enriched and iron-fortified foods. Although heme iron has been shown to be more readily absorbed by the body, most dietary iron is non-heme.
Iron deficiency is the most common nutrient deficiency in the US and around the world. Iron deficiency causes anemia which reduces the oxygen carried to tissue. Donating blood regularly, excessive menstrual bleeding, some medications that interfere with the absorption of iron (such as antacids), and pregnancy and lactation can all contribute to iron deficiency. The elderly, vegetarians and children are often iron deficient. People who are low in iron may experience weakness, fatigue, an inability to focus, increased susceptibility to illness, hair loss, lack of balance, headaches, brittle nails, apathy and depression. They may also crave or eat inedible materials such as dirt, clay, laundry starch, charcoal, and lead paint chips, a behavior called pica. Iron deficiency is associated with learning disabilities and a lower IQ in children and Harvard researchers recently determined that that iron deficiency may play a key role in female infertility.
Chronic iron overload, on the other hand, can cause many of the same symptoms, including loss of appetite, fatigue, weight loss, headaches, bronze or gray hue to the skin, dizziness, nausea, and shortness of breath. However, this condition usually only occurs in people who have regular blood transfusions, take iron supplements or have a genetic disorder called hemachromatosis. Men are at a greater risk for iron overload than a deficiency because they do not regularly lose iron.
Iron poisoning can occur when large quantities of iron-containing supplements are ingested and can cause nausea, vomiting, damage to the lining of the intestinal tract, shock, and liver failure. It is a leading cause of death among children.
The iron present in whole grains is contained in the bran and germ. The milling process that turns whole grains into refined grains removes the bran and germ, eliminating approximately 75 percent of the iron. Although many refined grains are fortified with iron, it does not absorb as well as naturally occurring iron. And while cooking with iron cookware adds iron to food, it can eventually lead to iron toxicity.
Our bodies absorb iron as it's needed; for example, during children's growth spurts and during pregnancy and lactation. Certain nutrients increase iron absorption, such as ascorbic acid (vitamin C), copper, cobalt, manganese and amino acids, while others - such as calcium - decrease its absorption. While oral contraceptives don't increase absorption, they can help women maintain their iron levels by reducing the amount of blood lost during menstruation.
The regular use of antacids and low stomach acid can decrease the body's ability to absorb iron, as can the caffeine and tannins in coffee and tea. While the effect from tannins does not need to be a consideration for people with healthy iron levels, those who are iron deficient should wait an hour or more after meals before drinking caffeinated teas. In addition, the phosphates found in soda, phytates found in whole grains, and oxalates found in spinach and chocolate can all decrease iron absorption. The phytates and oxalates can form complexes with the iron, which prevents its absorption in the intestinal track.
Iron can also block the absorption of certain medications such as sulfasalazine, tetracycline, thyroid hormone medications, carbidopa and methyldopa.
However, iron may help prevent and treat many conditions including alcoholism, attention deficit disorder, colitis, diabetes, iron deficiency anemia, leukemia, parasitic infections, restless leg syndrome, stomach ulcers, and tuberculosis.
Surprisingly, many common herbs, such as thyme, turmeric, cumin seeds, and dill weed, are high in iron. However, because they are used in such limited quantities, they are not considered reliable sources of daily dietary iron.
Good Sources of Iron Include:
- Soybeans (cooked)
- Lentils (cooked)
- Spinach (boiled)
- Swiss Chard (boiled)
- Blackstrap molasses
- Mustard greens (boiled)
- Shiitake mushrooms (raw)
- Turnip greens
- Green beans