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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 development and protein synthesis
Recommended Dietary Allowance [RDA] or Adequate Intake
Upper Limits [UL]
|0-6 months||110||Not determinable|
|7-12 months||130||Not determinable|
|19 years and older||150||1,100|
|Pregnancy (18 or younger)||220||900|
|Pregnancy (19-50 years)||220||1,100|
|Lactation (18 or younger)||290||900|
|Lactation (19-50 years)||290||1,100|
Too Little Iodide
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.
Goiter is not as common as it once was in the US because of iodized salt however, iodide deficiency is a major public health issue in many regions around the world.
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.
Too Much Iodide
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 6 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:
- Coarse, brittle hair; hair loss
- Facial puffiness
- Dry skin
- Swollen hands or feet
- Cold intolerance
- Weight gain
- Achy feeling all over
- Depression and irritability
- Menstrual abnormalities or infertility
When more hormones are released than necessary, the result is hyperthyroidism.
Major Food Sources
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||1.5 gram||71|
|Cod, cooked||3 ounces||99|
|Milk, reduced fat||1 cup||56|
|Lima beans, cooked||½ cup||8|
Tips for Increasing Your Iodide Intake
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.
American Thyroid Association
Eat Right—American Academy of Nutrition and Dietetics
Dietitians of Canada
The Thyroid Foundation of Canada
Institute of Medicine. Dietary reference intakes: elements. Institute of Medicine website. Available at: http://www.iom.edu/~/media/Files/Activity%20Files/Nutrition/DRIs/DRI%5FElements.ashx. Accessed May 9, 2016.
Iodine. EBSCO Natural and Alternative Treatments website. Available at: http://www.ebscohost.com/biomedical-libraries/natural-alternative-treatments. Updated August 2013. Accessed May 9, 2016.
Iodine. Oregon State University Linus Pauling Institute website. Available at: http://lpi.oregonstate.edu/infocenter/minerals/iodine. Accessed May 9, 2016.
Iodine deficiency. American Thyroid Association website. Available at: http://www.thyroid.org/iodine-deficiency. Accessed May 9, 2016.
Iodine fact sheet for health professionals. Office of Dietary Supplements website. Available at: http://ods.od.nih.gov/factsheets/Iodine-HealthProfessional. Updated February 11, 2016. Accessed May 9, 2016.
Papillary thyroid cancer. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated September 10, 2015. Accessed May 9, 2016.
- Reviewer: Michael Woods, MD
- Review Date: 05/2016
- Update Date: 06/10/2014