The trace mineral iodine is necessary for human life. Deficiencies are rare in industrialized countries, but can still be seen occasionally in individuals with restrictive diets, such as strict vegans and people who have increased iodine needs, such as pregnant women. Fortunately, iodine can be found in a wide variety of foods, although levels can differ significantly, depending on where the particular food originated.
Importance
Iodine can be found participating in a variety of essential bodily functions. Iodine assists in metabolism, the conversion of food to energy. Iodine helps maintain the thyroid gland and is incorporated into thyroid hormones. These thyroid hormones affect reproduction, growth, development and metabolism. Iodine deficiency can cause brain damage, hypothyroidism, goiter and developmental problems. Deficiencies during pregnancy can lead to severe mental retardation in the child. Most adults need 150 mcg of iodine every day.
Iodized Salt
Iodized salt is the main source of iodine worldwide. According to the Linus Pauling Institute, about 70 percent of all households in the world use iodized salt. Iodine is added to salt in more than 70 countries around the world to combat iodine deficiency. Iodized salt contains 77 mcg of iodine per gram. Many processed foods are made with iodized salt, including bread and canned goods.
Seafood
The ocean is a natural reservoir of iodine, so seafood tends to contain a lot of this nutrient. Cod is a particularly good source, containing 99 mcg in 3 oz. of fish. A 3 oz. serving of shrimp contains about 35 mcg, and a half can of tuna has 17 mcg. Seaweeds, also referred to as sea vegetables, are another excellent source. Some types might contain up to 4.5 mg of iodine in 0.25 oz. of dried seaweed. In particular, kelp and wakame contain high levels of iodine.
Dairy Products
Dairy products are often rich in iodine because the cows that produce the milk are fed iodine-rich animal feed. One cup of cow's milk contains 56 mcg of iodine. Yogurt and cheese are other good sources of iodine. The iodine level of dairy products can vary widely, however, depending on what the cow ate. Cows that graze on grass in iodine-poor soil have much lower levels in their system and produce milk with lower iodine levels.
Plant Sources
Fruits, vegetables and grains contain widely varying levels of iodine, ranging from 5 mcg per pound to 0.5 mg per pound. Plants grown in iodine-rich soil contain much higher levels than those grown in soil poor in iodine. Potatoes grown in iodine-rich soil can have up to 60 mcg in a medium potato. A half-cup of cream-style corn contains about 14 mcg.
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