Diet - iodine

Alternative names 
Iodine in diet

Iodine is a trace mineral and an essential nutrient.

Iodine is essential for the normal metabolism of cells. It is a necessary nutrient for the production of thyroid hormones and normal thyroid function.

Food Sources
Iodized salt is the primary food source of iodine. Iodine is also widely available in seafood; cod, sea bass, haddock, and perch are good sources. Kelp is the most common vegetable seafood that is a rich source of iodine. Dairy products and plants grown in soil that is rich in iodine are also good sources.

Side Effects
Deficiency of iodine may occur in areas that have iodine-poor soil. Many months of iodine deficiency in the diet can cause goiter and/or hypothyroidism. With decreased iodine, the thyroid cells and the gland become enlarged. The deficiency is more prevalent in women than in men, and more common in pregnant women and adolescents. Iodine intake is stressed as a preventive measure because a goiter caused by iodine depletion can cause cretinism (a form of physical and mental retardation). Cretinism is extremely rare in the U.S. because iodine deficiency is generally not a problem.

Iodine toxicity is rare in the U.S. Very high intake of iodine can reduce the function of the thyroid gland.

These are the recommended daily allowances:

  • infants - 40 to 50 micrograms.  
  • children       o age 1 to 3 years - 70 micrograms       o age 4 to 6 years - 90 micrograms       o age 7 to 10 years - 120 micrograms       o age 11+ years - 150 micrograms  
  • pregnant women - 175 micrograms  
  • lactating women - 200 micrograms

A 1/4 teaspoon of iodized table salt provides 95 micrograms of iodine. A 6- ounce portion of ocean fish provides 650 micrograms of iodine. Most people are able to meet their iodine requirements by eating seafood, seaweed, iodized salt, and plants grown in iodine-rich soil. When buying salt make sure that is the iodized kind.

Johns Hopkins patient information

Last revised: December 3, 2012
by Gevorg A. Poghosian, Ph.D.

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