Iodine in diet

Iodine is needed for the cells to change food into energy. Humans need iodine for normal thyroid function, and for the production of thyroid hormones.

Iodized salt is table salt with iodine added. It is the main food source of iodine.

Seafood is naturally rich in iodine. 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 also contain iodine.

Other good sources are plants grown in iodine-rich soil.

Lack of enough iodine (deficiency) may occur in places that have iodine-poor soil. Many months of iodine deficiency in a person's diet may cause goiter or hypothyroidism. Without enough iodine, the thyroid cells and the thyroid gland become enlarged.

Lack of iodine is more common in women than in men. It is also common in pregnant women and older children. Getting enough iodine in the diet may prevent a form of physical and mental abnormality called cretinism. Cretinism is very rare in the United States because iodine deficiency is generally not a problem.

Iodine poisoning is rare in the US. Very high intake of iodine can reduce the function of the thyroid gland. Taking high doses of iodine with anti-thyroid medicines can have an additive effect and could cause hypothyroidism.

The best way to get the daily requirement of essential vitamins is to eat a balanced diet that contains a variety of foods from the food guide plate.

Iodized table salt provides 45 micrograms of iodine in a 1/8 to 1/4 ounce teaspoon portion. 1/4 teaspoon of 45 micrograms of iodine. A 3 oz portion of cod provides 99 micrograms. Most people are able to meet the daily recommendations by eating seafood, iodized salt, and plants grown in iodine-rich soil. When buying salt make sure it is labeled "iodized."

The Food and Nutrition Board at the Institute of Medicine recommends the following dietary intake for iodine:

Infants

• 0 to 6 months: 110 micrograms per day (mcg/day)*
• 7 to 12 months: 130 mcg/day*

*AI or Adequate Intake

Children

• 1 to 3 years: 90 mcg/day
• 4 to 8 years: 90 mcg/day
• 9 to 13 years: 120 mcg/day

Adolescents and adults

• Males age 14 and older: 150 mcg/day
• Females age 14 and older: 150 mcg/day
• Pregnant females of all ages: 220 mcg/day
• Lactating females of all ages: 290 mcg/day

Specific recommendations depend on age, gender, and other factors (such as pregnancy). Women who are pregnant or producing breast milk (lactating) need higher amounts. Ask your health care provider which amount is best for you.

Mason JB. Vitamins, trace minerals, and other micronutrients. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 218.

Smith B, Thompson J. Nutrition and growth. In: The Johns Hopkins Hospital; Hughes HK, Kahl LK, eds. The Harriet Lane Handbook. 21st ed. Philadelphia, PA: Elsevier; 2018:chap 21.