Your body needs iodine, a mineral, to work properly. The thyroid gland, for example, uses iodine to make the thyroid hormone thyroxin. Most iodine is in the form of iodide. These terms are often used interchangeably.
Iodide helps to:
- Regulate metabolic rate
- Regulate growth and development
- Promotes bone and protein synthesis
Recommended Dietary Allowance [RDA] or Adaquate Intake
Upper Limits [UL]
|0-6 months||110||Not determinable|
|7-12 months||130||Not determinable|
|19 years and older||150||1,100|
(18 or younger)||220||900|
|Lactation (18 or younger)||290||900|
|Lactation (19-50 years)||290||1,100|
Iodine deficiency can cause a range of problems, including mental retardation, hypothyroidism,
goiter, and other growth and developmental problems. Thyroid enlargement (goiter) is one of the early signs of iodine deficiency. Not getting enough iodine is especially harmful for the developing brain, such as during pregnancy and in infants. This is why the American Thyroid Association recommends that pregnant and breastfeeding women take a daily prenatal supplement that contains iodine.
Because we have iodized salt in the US, goiter is rarely seen. If eaten in large quantities, some foods, like raw turnips and rutabagas, have chemicals that can cause goiters and inhibit thyroid gland functions. These chemicals, called goitrogens, are destroyed when the foods are cooked, so problems are uncommon.
The thyroid can also become enlarged if you have too much iodide in your diet, though this is rare in the US. This “toxic goiter” is caused by elevated concentrations of thyroid stimulating hormone (TSH). This is often seen in people who eat a lot of seaweed, which can add a significant amount of iodide to the diet. Iodide levels up to 1 milligram (more than six times the RDA) appear to be safe.
When the thyroid gland releases fewer hormones than the body needs, the result is
hypothyroidism. Some of the symptoms include:
When more hormones are released than necessary, the result is
hyperthyroidism. Some symptoms include:
- Heat intolerance
Enlarged thyroid gland (goiter)
- Heart palpitations
- Increased sweating
- Nervousness, irritability
- Redness, swelling, and protrusion of the eyes
- Shortness of breath
- Increased number of bowel movements
no menstrual period
A low iodide intake can especially impact children, causing a condition called
cretinism. If not treated, the condition can lead to
and abnormal growth. Iodine supplements can help reverse some of the affects. People who have a low iodide intake may be at risk of getting
thyroid cancer, although it is not known exactly what causes the disease.
Iodide is found naturally in food grown in or near coastal seas. Seafood is naturally high in iodide, as are plants grown near the sea. Molasses and iodized salt are also good sources. Most people get plenty of iodide from the iodized salt in their diets, since only ½ teaspoon of iodized salt provides enough iodide to reach an adult's RDA for the day. The sea salt found in health food stores is generally not a good source because iodide is lost during processing.
|Table salt, iodized||¼ teaspoon||100|
|Cod, cooked||3 ounces||87|
|Potato, cooked||1 medium||7|
|Spinach, cooked||½ cup||5|
In general, there is little need to increase your iodide intake. Most people in the US get plenty from their diets, much of this coming from iodized salt. But if you use sea salt (or another type of salt) that does not have iodide, you can get the mineral from seafood or other sources. This is also true if you are on a low-sodium diet. Talk to your doctor if you are concerned about how much iodide you are getting.
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Philadelphia, PA: Lippincott-Raven Publishers; 1998
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The Vitamin Foundation. Iodine deficiency. The Vitamin Foundation website. Available at: . Accessed July 12, 2012.
Last reviewed July 2012 by Brian Randall, MD
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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