The average human contains about 5g (1 tsp.) of iron in all living cells. Because iron plays a vital role in immune function, cognitive development, temperature regulation, energy metabolism and oxygen transport to muscle cells, the Recommended Daily Allowance (RDA) of iron for adult males is 8mg per day and for females 18mg per day. Older adults may need less (7mg to 8mg) and lactating women, teens, and children between 10mg and18mg.
Absorption
Iron absorption is not equal in all foods. Plant foods that contain iron, such as legumes and leafy vegetables, have phytic acid that binds iron to itself. Because humans lack special enzymes to break apart the bond, the iron in these foods passes through the digestive tract and into feces.
Animal sources of iron lack this bond; therefore, this source is the best for iron intake.
Seafood
Oysters (steamed) have the highest iron content per serving (about 7mg for three oysters). Tuna, salmon, shrimp and clams also contain similar iron content per serving.
Beef, Poultry and Pork
Many Americans get their source of iron from hamburgers, pork chops, sauerkraut, steak, pot roast and ham. However, these sources are high in saturated fat and can be expensive of most people.
Consuming poultry (particularly white meat chicken) as an iron source is better than the previous two because it has less saturated fat and is more economic for some people.
Tofu
Originated in China, tofu is an excellent source of iron for vegetarians, people with low incomes, or to improve health without heavy reliance on meat consumption. Four ounces of tofu can provide about 33 percent of the RDA.
Legumes, Fruits, and Leafy Vegetables
Although the iron absorption rate is low for plant-based foods, you can increase the bioavailability of iron absorption by soaking legumes and vegetables in warm salt water overnight before cooking. When eaten with other foods that are high in vitamin C, iron absorption rate increases. Therefore, vegans can still get adequate iron in their diet when prepared properly.
Excellent sources of iron in this group include kidney beans, spinach, peas, broccoli, dried apricots, peaches and prune juice.
Fortified Grains
Many cereals, bread and other grain products contain added iron in the form of ferrous sulfate (FeSO4). The added iron is carefully measured by food companies to ensure that consumers do not eat too much of this mineral, which can cause liver and heart damage.
References
- * "Perspectives in Nutrition"; Gordon Wardlaw and Margaret Kessel; 2002
- The World's Healthiest Foods, Essential Guide for the Healthiest Way of Eating; George Mateljan; 2006
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