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Iron: it can be too much of a good thing.

Chances are, your mother (or grand-mother) probably told you to eat your meat at dinner to avoid "iron-poor" blood. It's true enough that iron is an essential mineral; it's a component in cell growth and oxygen transport to your body's tissues. If you don't get enough, you may feel tired and have decreased performance and immunity. However, even in the case of iron, you can get too much of a good thing.
Iron: Recommended Dietary Allowances *

Age           Male (mg/day)   Females (mg/day)

19-50 years              18                 18

51+ years                 8                  8

Source: Institute of Medicine; mg=milligrams

* RDA for adults, non-pregnant, non-lactating

Looking for iron. Two types of iron are in foods: heme, found in animal foods (like red meat, poultry and fish) that originally contained hemoglobin; and nonheme, found in plant foods such as beans and lentils. While you only absorb 10-15 percent of dietary iron (heme is more absorbable than nonheme), your body stores it; when iron stores drop, your absorption increases, and when stores are high, absorption decreases to protect against toxicity. Studies suggest that most adult men and postmenopausal women meet their needs for iron, but intakes are low in females of childbearing age and children.

Iron overload? Recent attention centers upon the possibility that too much iron--in particular, heme--may pose health problems. Some scientists question whether home iron may be one factor behind the risk of cardiovascular disease (CVD) seen with high red meat intake. A 40 percent higher risk of dying from heart attack, stroke, or other CVD was found among high red-meat eaters, compared with low red meat consumers (Archives of Internal Medicine, 2012.)

Researchers have found that populations with low iron stores tend to have lower rates of heart disease, and those with high iron stores have higher rates. In a 2007 Harvard study, which followed 54,455 women from 1980 through 2000, higher consumption of heme iron and red meat was linked with increased CVD risk among women with type 2 diabetes. However, the National Institutes of Health reports that not all studies have found an increased risk of CVD among people with high iron status, making it difficult to make a final conclusion.
Iron in Foods

Heme Iron Sources     Serving    Iron (mg)     %DV

Chicken liver,           3 oz         11.0      61

Beef, chuck, lean,       3 oz          3.1      17

Tuna, light, canned       3 oz         1.3       7
in water

Turkey, light meat,       3 oz         1.1       7

Nonheme Iron Sources    Serving   Iron (mg)    %DV

Ready-to-eat cereal,      3/4 C        18.0    100
iron fortified

Soybeans, boiled            1 C         8.8     48

Lentils, boiled             1 C         6.6     37

Spinach, fresh,           1/2 C         3.2     18
boiled, drained

Source: USDA database; %DV=Percent Daily Value,
based on 2000 calories/day; oz=ounce,
c=cup, mg=milligrams

There is a potential for iron toxicity--little is excreted from the body, allowing iron possibly to accumulate in tissues and organs. As with all nutrients, it's important to seek a balance through a variety of foods rather than supplements. However, for some individuals, iron supplements may be warranted (when prescribed by your physician) to correct iron deficiency or to meet increased nutritional needs during pregnancy or other health conditions.
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Title Annotation:Research Update
Publication:Environmental Nutrition
Geographic Code:1USA
Date:Jul 1, 2013
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