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Anemia

Description

An in-depth report on the types, diagnosis, treatment, and prevention of anemia.

Alternative Names

Iron deficiency; Pernicious anemia

Dietary Factors

Iron found in foods is either in the form of heme or non-heme iron:

• Heme Iron . Foods containing heme iron are the best sources for increasing or maintaining healthy iron levels. Such foods include (in decreasing order of iron-richness) clams, oysters, organ meats, beef, pork, poultry, and fish.
• Non-Heme Iron . Non-heme iron is less well-absorbed. About 60% of the iron in meat is non-heme (although meat itself helps absorb non-heme iron). Eggs, dairy products, and iron-containing vegetables have only the non-heme form. Such vegetable products include dried beans and peas, iron-fortified cereals, bread, and pasta products, dark green leafy vegetables (chard, spinach, mustard greens, kale), dried fruits, nuts, and seeds.

The absorption of non-heme iron often depends on the food balances in meals. The following foods and cooking methods can enhance absorption of iron:

• Meat and fish not only contain heme iron -- the best form for maintaining stores -- but they also help absorb non-heme iron.
• Increasing intake of vitamin-C rich foods, such as orange juice, may enhance absorption of non-heme iron, although it is not clear if it improves iron stores in iron-deficient people. In any case, vitamin-C rich foods are healthy and include broccoli, cabbage, citrus fruits, melon, tomatoes, and strawberries.
• Riboflavin (vitamin B2) may help enhance the response of hemoglobin to iron. Food sources include dairy products, liver, and dried fortified cereals.
• Cooking methods can enhance iron stores. Cooking in cast iron pans and skillets is well-known to increase the iron content of food. According to one study, boiling, steaming, or stir-frying in utensils composed of any material significantly increased the release of non-heme iron stored in vegetables.

Certain nutrients interfere with the body's absorption of dietary iron. They include:

• Polyphenols (found in tea, coffee, red wine, berries, apples)
• Phytates (found in foods such as seeds, dried beans, soy, and bran). Such foods are typically high in fiber. (It is often believed that fiber itself impedes iron absorption, but researchers report that it has little or no effect.)
• Calcium. Calcium impairs the absorption of heme and non-heme iron. However, calcium intake must be quite high to cause any significant problems. For example, a 2002 study reported that cheese had no effect on iron absorption from meals rich in heme and non-heme iron.

Sources of Vitamins B12 and Folate. Vitamins B12 and folate are important for prevention of megaloblastic anemia and for good health in general.

• The only natural dietary sources of B12 are animal products, such as meats, dairy products, eggs, and fish (clams and oily fish are very high in B12). As is the case with other B vitamins, however, B12 is added to commercial dried cereals. The recommended daily allowance (RDA) is 2.4 mcg a day. Deficiencies are rare in young people, although the elderly may have trouble absorbing natural vitamin B12 and require synthetic forms from supplements and fortified foods.

• Folate is best found in avocado, bananas, orange juice, cold cereal, asparagus, fruits, green, leafy vegetables, dried beans and peas, and yeast. The synthetic form, folic acid, is now added to commercial grain products. Vitamins are usually made from folic acid, which is about twice as potent as folate. Many experts now recommend that adults have 400 mcg of folic acid daily -- considerably higher than standard recommendations of 400 mcg of folate . Women who are trying to conceive, who are pregnant, and who are breastfeeding should take 400 mcg of folic acid.

Recommended Daily Allowance for Iron The Recommended Daily Allowance (RDA) of iron for people who are not iron deficient varies by age group and other risk factors. (Iron supplements are rarely recommended in people without evidence of iron deficiency or anemia.) The RDA recommends these daily amounts of iron: Children 1 - 3 years old: 10 mg Teenage boys: 12 mg Teenage girls and premenopausal women: 15 mg Pregnant or nursing women: 30 mg Adult men (up to age 50): 10 mg Older men and women (over age 50): 10 mg

Preventing Anemia in Infants and Small Children

The main source of iron for an infant from birth to 1 year of age is in milk, either from breast milk, iron-fortified infant formula, or cereal. The best methods for preventing iron deficiency during infancy are:

Breastfeeding and Iron-Supplemented Formulas. Mothers should be encouraged to breastfeed their babies for their first year. Up to half of the iron in breast milk is absorbed by the baby and is sufficient to prevent anemia for the first 4 - 6 months, assuming that the mother had adequate iron stores during pregnancy. Breast milk itself is low in iron, but if the mother's diet is healthy, vitamin C and lactose in the breast milk may enhance iron absorption. Breastfed babies should have iron supplements after 4 - 6 weeks, even if they are still nursing.

Infants who are not breastfed should start with iron-fortified formulas. Most experts strongly discourage the use of low-iron formulas (less than 4.0 mg/L). However, a 2002 study suggested that formulas with iron levels as low as 1.6 mg Fe/L provide sufficient iron to infants and higher amounts do not add any benefit. Parents should discuss the best formula with their doctor. Children given iron supplements may have a slightly higher risk for diarrhea. Experts advise against cow's milk for the first year of life.

Recommendations for Toddlers. Toddlers who did not have iron supplements during infancy should be checked for iron deficiency. After the first year, children should be given a varied diet that is rich in sources of iron, B vitamins, and vitamin C. Milk does not contain enough iron and can decrease children's appetite for iron-rich foods. Toddlers older than 1 year should not drink more than 2 cups of milk a day. A preference for apple juice over vitamin-C rich orange juice does not reduce iron absorption in children with any otherwise healthy diet.

• Review Date: 1/17/2007
• Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital

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