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With so much attention being paid to dietary excesses, it's easy to forget that iron deficiency and anemia are still widespread problems in Canada. Infants, children, adolescents, vegetarians and women are most at risk. Although no national statistics have been compiled since 1973, studies suggest that 20 to 30 per cent of premenopausal Canadian women have iron intakes below the Recommended Nutrient Intake (RNI) of 13 mg a day. Young children too are often low in iron. An estimated one to three per cent of 6 to 12 month old infants from middle income city families, and as many as 10 per cent of 18-month olds from low-income families, are iron-deficient. Iron deficiency can arise for many reasons - for instance, not getting enough from the diet, difficulties in absorbing it or through blood losses (from menstrual periods, bleeding ulcers or other causes).
Why our bodies need iron
Vital to health, iron has several key functions in the body. Best known is its role in transporting oxygen to the tissues. Nearly three quarters of the iron in the body occurs within a compound called hemoglobin - the pigment inside red blood cells that binds with oxygen and carries it to all body cells. Hemoglobin also helps remove carbon dioxide from blood to be exhaled, and iron-containing enzymes take part in various oxidation reactions and electron-transport mechanisms. Iron may also contribute to psychomotor and mental processes. (Lack of iron can lead to the condition known as anemia.)
Maintaining the body's iron balance
In order to maintain a healthy iron balance, the body must absorb enough from the daily diet to offset the amounts lost in sweat and urine, in cells shed from the skin and interior surfaces (such as the intestines), and - in women - amounts lost by normal menstrual bleeding. On average, adults lose 1 to 2 mg of iron a day. To replace it, they must ingest much more from food because only a small proportion of dietary iron is absorbed. The human body conserves iron efficiently and gears absorption to the amount stored. Iron absorption is regulated so that the body absorbs only as much as it can safely use, to avoid "iron overload," which can be dangerous.
The more iron stored in the body, the less is absorbed from food. Any extra iron is stored in the liver, spleen or bone marrow, ready for use if there should be a shortage. If dietary absorption isn't enough for the body's needs, iron is released from the stores to meet the shortfall. Absorption from food improves whenever iron stores are low. If a "negative" (low) iron balance is prolonged, iron deficiency - perhaps ultimately anemia (with red blood cells short of hemoglobin) - will develop. However, some people can remain marginally iron deficient for long periods without developing anemia.
What affects the body's iron absorption?
Getting enough iron means more than just adding up the milligrams of iron in the …