Iron deficiency is the most common nutrient deficiency in the United States, and iron is critical to human life. There are two forms of dietary iron: heme and nonheme. Heme is in animal products and is the most efficiently absorbed. Nonheme is in plant foods and is poorly absorbed comparatively. The RDA for iron is 10 mg for males and 15 mg for females.
Causes of Deficiency
Iron deficiency can be caused by an increased requirement, blood loss, not getting enough in the diet, not absorbing it properly or a combination of these. Groups at highest risk for deficiency are infants under 2, teenage girls, women of childbearing age, pregnant women and the elderly. Too little stomach acid is the most common reason for decreased absorption and is especially problematic for the elderly. Vegetarians and vegans need to take care to not only get enough iron but also vitamin C to help with absorption.
Consequences of Deficiency
Oxygen delivery to the tissues is impaired as well as the activity of certain enzymes in various tissues. This can lead to anemia, excessive menstrual loss, learning disabilities, impaired immune function and chronic fatigue.
Animal Sources
Clams, grass-fed sirloin steak, shrimp, turkey breast, chicken breast and grass-fed beef liver are the best sources of heme iron. Liver from grass-fed cows is preferable because corn-fed cattle in feed lots develop diseased livers and are treated with antibiotics and hormones.
Plant Sources
Lentils, tofu, blackstrap molasses, quinoa, beans and Swiss chard are the best sources of nonheme iron. To increase iron absorption, these foods should be eaten with those highest in vitamin C, including red chili peppers, red sweet peppers and dark green leafy vegetables.
Supplementation
If whole food sources do not supply enough iron, supplementation may be required. Iron supplements often cause constipation, nausea and heartburn. For iron deficiency, Dr. Murray suggests a high-quality aqueous (hydrolyzed) liver extract to provide an intake of 4 to 6 milligrams of heme iron. Supplementation should be restricted to cases of iron deficiency and menstruating, pregnant or lactating women due to risks of iron overload.
References
- The Omnivore's Dilemma; Michael Pollan; 2007
- The Encyclopedia of Nutritional Supplements; Michael T. Murray, N.D.; 1996
Member Comments