Anemia is a reduction in the number of red blood cells (RBCs); in the amount of hemoglobin in the blood (hemoglobin is the iron-containing pigment of the red blood cells that carry oxygen from the lungs to the tissues); and in another related index called hematocrit (the volume of RBCs after they have been spun in a centrifuge). All three values are measured on a complete blood count, also referred to as a CBC. Iron-deficiency anemia can be distinguished from most other forms of anemia by the fact that it causes RBCs to be abnormally small and pale, an observation easily appreciated by viewing a blood sample through a microscope.
Iron deficiency also can occur, even if someone is not anemic. Symptoms of iron deficiency without anemia may include fatigue, mood changes, and decreased cognitive function. Blood tests (such as serum ferritin, which measures the body’s iron stores) are available to detect iron deficiency, with or without anemia.
Iron deficiency, whether it is severe enough to lead to anemia or not, can have many non-nutritional causes (such as excessive menstrual bleeding, bleeding ulcers, hemorrhoids, gastrointestinal bleeding caused by aspirin or related drugs, frequent blood donations, or colon cancer) or can be caused by a lack of dietary iron. Menstrual bleeding is probably the leading cause of iron deficiency. However, despite common beliefs to the contrary, only about one premenopausal woman in ten is iron deficient.1 Deficiency of vitamin B12, folic acid, vitamin B6, or copper can cause other forms of anemia, and there are many other causes of anemia that are unrelated to nutrition. This article will only cover iron-deficiency anemia.
What are the symptoms of iron-deficiency anemia?
Some common symptoms of anemia include fatigue, lethargy, weakness, poor concentration, and impaired immune function. In iron-deficiency, fatigue also occurs because iron is needed to make optimal amounts of ATP—the energy source the body runs on. This fatigue usually begins long before a person is anemic. Said another way, a lack of anemia does not rule out iron deficiency in tired people. Another symptom of anemia, called pica, is the desire to eat unusual things, such as ice, clay, cardboard, paint, or starch. Advanced anemia may also result in lightheadedness, headaches, ringing in the ears (tinnitus), irritability, pale skin, unpleasant sensations in the legs with an uncontrollable urge to move them (restless legs syndrome), and getting winded easily.
Dietary changes that may be helpful for iron-deficiency anemia
Iron deficiency is not usually caused by a lack of dietary iron alone. Nonetheless, a lack of iron in the diet is often part of the problem, so ensuring an adequate supply of iron is important for people with a documented deficiency. The most absorbable form of iron, called “heme” iron, is found in meat, poultry, and fish. Non-heme iron is also found in these foods, as well as in dried fruit, molasses, leafy green vegetables, wine, and most iron supplements. Acidic foods (such as tomato sauce) cooked in an iron pan can leech iron into the food and thus also be a source of dietary iron.
Vegetarians eat less iron than non-vegetarians, and the iron they eat is somewhat less absorbable. As a result, vegetarians are more likely to have reduced iron stores.2 Vegetarians can increase their iron intake by emphasizing iron-containing foods within their diet (see above), or in some cases by supplementing iron, if needed.
Coffee interferes with the absorption of iron.3 However, moderate intake of coffee (4 cups per day) may not adversely affect risk of iron-deficiency anemia when the diet contains adequate amounts of iron and vitamin C.4 Black tea contains tannins that strongly inhibit the absorption of non-heme iron. In fact, this iron-blocking effect is so effective that drinking black tea can help treat hemochromatosis, a disease of iron overload.5 Consequently, people who are iron deficient should avoid drinking tea.
Fiber is another dietary component that can reduce the absorption of iron from foods. Foods high in bran fiber can reduce the absorption of iron from foods consumed at the same meal by half.6 Therefore, it makes sense for people needing to take iron supplements to avoid doing so at mealtime if the meal contains significant amounts of fiber.
Nutritional supplements that may be helpful for iron-deficiency anemia
Before iron deficiency can be treated, it must be diagnosed and the cause must be found by a doctor. In addition to addressing the cause (e.g., avoiding aspirin, treating a bleeding ulcer, etc.), supplementation with iron is the primary way to resolve iron-deficiency anemia.
If a doctor diagnoses iron deficiency, iron supplementation is essential. Though some doctors use higher amounts, a common daily dose for adults is 100 mg per day. Even though symptoms of deficiency should disappear much sooner, iron deficient people usually need to keep supplementing with iron for six months to one year until the ferritin test is completely normal. Even after taking enough iron to overcome the deficiency, some people with recurrent iron deficiency—particularly some premenopausal women—need to continue to supplement with smaller levels of iron, such as the 18 mg present in most multivitamin-mineral supplements. This need for continual iron supplementation even after deficiency has been overcome should be determined by a doctor.
Liver extracts from beef are a rich natural source of many vitamins and minerals, including iron. Bovine liver extracts provide the most absorbable form of iron—heme iron—as well as other nutrients critical in building blood, including vitamin B12 and folic acid. Liver extracts can contain as much as 3–4 mg of heme iron per gram.
Taking vitamin A and iron together has been reported to help overcome iron deficiency more effectively than iron supplements alone.7 Although the optimal amount of vitamin A needed to help people with iron deficiency has yet to be established, some doctors recommend 10,000 IU per day.
Vitamin C increases the absorption of non-heme iron.8 Some doctors advise iron-deficient people to take vitamin C (typically 100–500 mg) at the same time as their iron supplement.9
Hydrochloric acid produced by the stomach improves the absorption of non-heme iron from food and supplements. 10 11 Some practitioners recommend a hydrochloric acid supplement (e.g., betaine hydrochloride [betaine HCl]), to enhance iron absorption in people with iron-deficiency anemia.
A high degree of association between iron-deficiency anemia and vitamin D deficiency in Asian children has been previously reported.12 In three different ethnic groups living in England, iron-deficiency anemia was found to be a significant risk factor for low vitamin D levels in children.13 These findings suggest that children with iron-deficiency anemia should be screened for vitamin D deficiency and be given vitamin D supplements if necessary.
Taurine has been shown, in a double-blind study, to improve the response to iron therapy in young women with iron-deficiency anemia.14 The amount of taurine used was 1,000 mg per day for 20 weeks, given in addition to iron therapy, but at a different time of the day. The mechanism by which taurine improves iron utilization is not known.
Caution: People who are not diagnosed with iron deficiency should not supplement with iron, because taking iron when it isn’t needed has no benefit and may do some harm. Adult iron supplements are the most common cause of fatal poisonings in children. Keep all iron supplements out of the reach of children.
Are there any side effects or interactions with iron-deficiency anemia?
Refer to the individual supplement for information about any side effects or interactions.