Iron is an essential mineral that the body requires in small amounts. It is widely available in foods including meat, poultry, and fish; also dried fruits, grains, and green leafy vegetables. Iron from plant sources is absorbed half as well as that from animal sources. The average diet provides about 10 to 20 mg of iron per day.
Iron is needed to manufacture hemoglobin, which enables red blood cells to transfer oxygen to the body's tissues. Severe or prolonged iron deficiency is the leading cause of anemia in the United States, affecting about five percent of women and two percent of men.
Iron Deficiency and Anemia:
Symptoms of iron deficiency anemia include easy fatigability, shortness of breath with mild exercise, and lethargy. Some evidence suggests that even mild iron deficiency, too mild to cause anemia, may cause fatigue and impair sports performance. Verbal learning and memory have been shown to improve when adolescent girls with iron deficiency anemia are treated with iron supplementation. Iron deficiency is most common in menstruating women but also is commonly seen in children and pregnant women. Low iron levels also may result from excessive bleeding, burns, and hemodialysis, as well as stomach and intestinal problems. Drugs that reduce stomach acid may also impair iron absorption. During pregnancy, iron deficiency can result in preterm delivery and low-birth-weight babies. Among children, iron deficiency is most common from ages 6 to 24 months, where it can cause developmental and behavioral problems. If iron deficiency is extremely severe, some of these problems can be irreversible.
How Much to Take? To Treat Anemia: In general, a typical adult dosage for correcting iron-deficiency anemia is 100 to 200 mg daily, divided into two or three separate doses. However, the recommended dose depends on the severity of the anemia and weight of the individual. Approximately two months is usually required to restore hemoglobin levels. Many more months of iron supplementation may be required to fully build up iron stores. To Prevent Anemia: The daily recommended intake of iron for healthy individuals depends on your gender and life stage. Most people are able to meet the requirement from their diet, from foods such as meat, poultry, and fish, as well as from dried fruits, grains, and green leafy vegetables. The average diet provides about 10 to 20 mg of iron per day. Bear in mind that iron from plant sources is absorbed half as well as that from animal sources.
The RDA for iron is 7 mg for children ages 1 to 3 and 10 mg for children ages 4 to 8. It then decreases to 8 mg for children ages 9 to 13. For males ages 14 to 18, the RDA is 11 mg; 19 and older, it decreases to 8 mg. For females, ages 14 to 18, the RDA is 15 mg; 19 to 50, it's 18 mg, decreasing to 8 mg ages 51 and older. Because of fetal needs, the RDA for pregnant women is to 27 mg. For breast-feeding women younger than age 18, the RDA is 10 mg; ages 19 and older, it's 9 mg. Also, postmenopausal women taking hormone replacement therapy should consume more iron because the therapy can cause periodic uterine bleeding. Oral contraceptives may reduce menstrual blood loss, so women taking them may need less daily iron. The FDA requires that dietary supplements state on their labels the % Daily Value for certain vitamins and minerals. However, this is based on an average and may not be appropriate for you, so use the RDAs above. When reading labels, remember that 1,000 mcg (micrograms) equals 1 mg (milligram) and that 1,000 mg equals 1 gram. Don't take too much!:
High daily amounts of iron can cause gastrointestinal distress, especially when iron supplements are consumed on an empty stomach. The Upper Tolerable Intake Level (UL) is 40 mg for children younger than age 13 and 45 mg for everyone else. However, these limits may be too high for people with hereditary hemochromatosis who are at unique risk for accumulating harmful levels of iron. Be aware that labels are unlikely to provide information indicating whether the ingredients exceed tolerable intake levels â€” the FDA doesn't require that information.
Avoiding Stomach Upset:
Several different forms of iron are used in supplements. The actual amount of usable "elemental" iron per milligram of iron compound varies depending on the form but, fortunately, the consumer doesn't need to do calculations â€” the manufacturer does this. The usable amount is what is supposed to appear on the label. Generally, the least expensive forms of iron are ferrous sulfate, ferrous fumarate, and ferrous gluconate. If you have trouble tolerating these forms of iron due to gastrointestinal discomfort, consider chelated iron, time-release iron supplements, ferrous bisglycinate, or ferrous glycinate. All of them are fairly expensive but may be the least likely to cause stomach upset. Another form, carbonyl iron, may present a reduced risk of harm in an accidental overdose. Carbonyl iron, consequently, is the ingredient many children's supplements contain and may be preferred by parents of small children. However, carbonyl iron requires adequate stomach acid for absorption. Therefore, it should be taken with food and not used with medications that reduce stomach acid. Injectable iron also is available under the supervision of a health professional. Still another way to deal with gastric upset is to take an iron supplement with food. Though combining the supplement with food may decrease iron absorption, taking it with a vitamin C-rich food may offset that effect because vitamin C boosts iron absorption. In fact, some iron supplements contain vitamin C as an added ingredient to aid absorption. Remember that many antacids can decrease iron absorption, as can soy protein, coffee, tea, eggs, whole-grain cereals and breads, and spinach. Iron absorption also can be reduced by high doses of calcium, zinc, manganese, magnesium or copper. When consuming one of these foods or high-dose mineral supplements, wait 1 to 2 hours to take your iron supplement. Cautions and Concerns:
Although iron supplements are safe and potentially helpful when taken in appropriate amounts, excessive iron intake can be harmful:
- The most common immediate side effect of iron supplements is gastrointestinal distress, a symptom that often occurs when a high-dose iron supplement is taken on an empty stomach.
- Other problems can occur with prolonged excessive intake of iron. For example, while pregnant women are generally encouraged to take iron supplements, supplementation beyond the recommended amount may increase complications of pregnancy. Also one study found that non-iron-deficient, breast-fed infants do not benefit from iron supplements. These infants might even experience an overall decrease in health if given iron supplementation.
- Observational studies have found associations between mildly excessive levels of stored iron in the body and heart disease, cancer and type 2 diabetes. This does not prove that excessive iron intake causes those diseases, but it does suggest a connection. On this basis, it appears prudent to suggest that people should not take iron supplements unless blood tests have shown them to be iron deficient. Note that non-vegetarian adult men and post-menopausal women are unlikely to lack adequate iron.
- Iron at greatly excessive doses taken continually can result in toxicity, causing cirrhosis, coronary heart disease, congestive heart failure, and other problems. Also, because vitamin C increases iron absorption, people who take very high doses of vitamin C (a gram or more daily) are at increased risk of iron toxicity. Toxicity is of particular concern for individuals with hemochromatosis, a genetic condition affecting 1 out of 200 to 500 people. With hemochromatosis, excessive amounts of iron build up in the body's tissues and organs.
Iron supplements also may reduce the absorption of certain drugs such as levodopa, levothyroxine, penicillamine, quinolone antibiotics, tetracycline antibiotics, and, possibly, ACE-inhibitors. Some of these drugs may, conversely, interfere with iron absorption. It is best to take these medications at a different time of day than when taking an iron supplement.Remember, iron supplements are a leading cause of poisoning in children younger than age 6. Just a few adult tablets can cause serious poisoning, so keep iron products away from children's reach. To help reduce the number of such poisonings, supplements containing 30 mg or more of iron (other than carbonyl iron) only can be sold in child-resistant bottles or in single-dose packaging.