Key Concepts

  • RDA – 150 mcg/day (Adults); 220 mcg (pregnancy); 290 mcg (lactation)
  • UL – 1,100 mcg/day
  • Food Sources: Seaweed, seafood, dairy, eggs, beans, potatoes

Recommended Dietary Allowance (RDA)

The RDA for iodine is 150 mcg/day for adults. During pregnancy the RDA increases to 220 mcg. During lactation the RDA is set at 290 mcg. RDA values vary by age for infants, toddlers, children, and teenagers.

Americans consume about 240-300 mcg/day.

Functions

Iodine is necessary for proper thyroid hormone function. The thyroid regulates growth, development, and metabolism.

Deficiency

Iodine deficiency can lead to goiter (abnormal enlargement of the thyroid). Iodine deficiency causes a decrease in thyroid hormone production (thyroxine – T4). In response to decreased blood T4 concentrations, the pituitary gland increases its output of thyroid stimulating hormone (TSH). When TSH levels remain high for extended periods of time, goiter can appear.

Cretinism, severely impaired mental and physical growth in infants), is caused by iodine deficiency. Iodine deficiency is recognized as the most common cause of preventable brain damage in the world. It is estimated that 2 billion people have an iodine deficiency.

A deficiency in selenium may exacerbate iodine deficiency.

Toxicity/Excess/Upper Intake Level (UL)

The UL is set at 1, 100 mcg/day. Excessive amounts of iodine consumed in the diet can cause goiter.

Food Sources

  • Seaweed, whole or sheet, 1 g – Variable (16 to 2,984 mcg) – 11% to 1,989% DV
  • Cod, baked, 3 ounces – 99 mcg – 66% DV
  • Yogurt, plain, low-fat, 1 cup – 75 mcg – 50% DV
  • Egg, 1 large – 24 mcg – 16% DV
  • Navy beans, cooked, 1/2 cup – 32 mcg – 21% DV
  • Potato with peel, baked – 1 medium – 60 mcg – 43% DV

Plants growing in iodine-rich soils (in coastal regions) tend to have more iodine.

Iodized salt contains 76 mcg of iodine/gram. Adequate intake of salt is about 4 grams per day. Therefore consuming iodized salt provides all of the necessary iodine needed each day. But, there are healthier, unprocessed forms of salt available, although they are not adequate sources of iodine. if using unprocessed salts, it is necessary to eat enough foods containing iodine each day or to take a supplement containing iodine. Many multivitamins contain iodine.

References/Resources

1. https://ods.od.nih.gov/factsheets/Iodine-HealthProfessional/

2. http://lpi.oregonstate.edu/mic/minerals/iodine

3. https://www.uptodate.com/contents/iodine-induced-thyroid-dysfunction

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