Iodine is an essential mineral. Adult men and women should have approximately 150 micrograms of iodine each day, and most people in the United States easily obtain this much through their diet, says the National Institutes of Health. By contrast, potassium iodide is a man-made salt compound of iodine. The Centers for Disease Control and Prevention cautions that you should not take potassium iodide unless you have been instructed to do so by your doctor or by public health officials.
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What They Do
Your body needs iodine to synthesize the two thyroid hormones thyroxine and triiodothyronine. Without adequate iodine, you may develop an enlarged thyroid gland, a condition known as goiter, and be more likely to suffer from neurological impairment. Pregnant women who lack iodine may have children who are stunted mentally and physically. Potassium iodide can be used as an iodine supplement, but it is most often administered to people who have been exposed to high amounts of radiation. The potassium iodide prevents the thyroid from taking up radioactive iodine, lessening the risk of thyroid cancer.
Where to Find Them
Rich natural sources of iodine include fish, shellfish, sea vegetables like seaweed, milk and potatoes. A 3-ounce serving of cooked cod contains 99 micrograms of iodine, or 66 percent of an adult's recommended daily allowance. Iodized salt is a common dietary source of iodine -- and often contains potassium iodide -- but you should limit your intake to keep your sodium level low. Potassium iodide does not occur naturally in food. The supplements, many of which have been approved by the Food and Drug Administration, can be purchased without a prescription.
Adults should not consume more than 1,100 micrograms of iodine per day. Getting more than this, either through food or from dietary supplements, may cause nausea, vomiting, diarrhea and a burning sensation in your throat or stomach. It may also cause goiter and increase your risk of thyroid cancer. Taking potassium iodide may cause salivary gland inflammation, rashes, digestive problems and sore gums. Some people may experience allergic reaction symptoms, such as facial swelling, trouble breathing, joint pain and fever.
The best way to ensure that you reach your daily requirement of iodine is to eat a varied diet, according to the Linus Pauling Institute. Supplementing with iodine isn't recommended, though pregnant and nursing women should speak to their doctor about taking additional iodine if they are concerned their diet doesn't provide enough. If you've been instructed to take potassium iodide following radiation exposure, take only the recommended dosage for the length of time advised by health officials.