Iodine is an essential mineral needed by the body for the production of thyroid hormones. Deficiencies can lead to a variety of health complications, and the World Health Organization considers iodine deficiency to be one of the most prevalent and preventable causes of brain damage. Adding iodine to salt has nearly eliminated iodine deficiencies in the United States, but the problem still exists in other countries.
Functions
Iodine is essential to the proper functioning of the thyroid gland. It is a component of the thyroid hormones T3 and T4, or triiodothyronine and thyroxine, respectively. Thyroid hormones interact with nearly every cell in the body, and are involved in metabolism, growth and development, according to the Linus Pauling Institute. It also stimulates the cardiovascular system and is important for mental functioning, reproduction and fetal growth. Circulating iodine in the blood is taken up and stored by the thyroid gland. When needed, thyroid hormones are synthesized using available iodine in the thyroid gland and then released into the bloodstream to perform their respective actions.
Sources
The primary source for iodine is iodized salt, which has been available for nearly a century. However, not all salt is iodized; the Salt Institute estimates that today approximately 70 percent of salt is supplemented with iodine. Seafood such as cod, salmon and tuna are rich in iodine, as well as seaweeds such as kelp, and also dairy products made from cow's milk. Vegetables grown in iodine-rich soils are also good sources, according to MedlinePlus.
Recommended Intake
The recommended amount of salt is generally met through normal diets, but individuals on a low-salt, low-seafood diet may be at risk for iodine deficiency. The recommended dietary allowance for iodine depends on the age of an individual, according to the Food and Nutrition Board at the Institute of Medicine. Infants up to 12 months of age should consume 110 to 130 micrograms per day. Children ages one to eight should consume 90 micrograms per day and children nine to 13 should consume 120 micrograms per day. It is recommended that adolescents and adults consume 150 micrograms per day. According to MedlinePlus, 1/4 tsp. of iodized salt contains 95 micrograms of iodine and six oz. of saltwater fish contains approximately 650 micrograms.
Iodine Deficiency
Iodine deficiencies can lead to a variety of health complications, referred to as iodine deficiency disorders. Common effects of iodine deficiency include an enlarged thyroid gland, or goiter, hypothyroidism, weight gain, loss of hair and sleep disturbances. Sufficient iodine is vital during pregnancy to prevent the development of cretinism, which can lead to severe mental retardation and dwarfism, according to the Linus Pauling Institute. Iodine deficiency is generally diagnosed by measuring the amount of iodine in the urine.
Goitrogens
Goitrogens are substances that interfere with the body's ability to utilize iodine for thyroid hormone production. They are found naturally in a variety of foods, and while they generally cause no problem they can exacerbate existing iodine deficiencies. Common foods containing goitrogens include cabbage, turnips, peanuts, broccoli, soybeans, mustard greens and cauliflower, according to the Vitamin and Herb University. Cooking these foods generally inactivates the goitrogens.
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