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 harvested from the sea. It 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.

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." There are 45 micrograms of iodine in 1/4 teaspoon of iodized salt. A 3 oz. portion of cod provides 99 micrograms of iodne.

Dosages for iodine, as well as other nutrients, are provided in the Dietary Reference Intakes (DRIs) developed by the Food and Nutrition Board at the National Academies of Sciences, Engineering, and Medicine. DRI is a term for a set of reference intakes that are used to plan and assess the nutrient intakes of healthy people. These values, which vary by age and sex, include:

• Recommended Dietary Allowance (RDA): The average daily level of intake that is enough to meet the nutrient needs of nearly all (97% to 98%) healthy people. An RDA is an intake level based on scientific research evidence.
• Adequate Intake (AI): This level is established when there is not enough scientific research evidence to develop an RDA. It is set at a level that is thought to ensure enough nutrition.

Dietary Reference Intakes for iodine:

Infants (AI)

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

Children (RDA)

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

Adolescents and adults (RDA)

• 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, sex, 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.

Diet - iodine

La Charite J. Nutrition and growth. In: Kleinman K, Mcdaniel L, Molloy M, eds. The Harriet Lane Handbook. 22nd ed. Philadelphia, PA: Elsevier; 2021:chap 21.

Mason JB, Booth SL. Vitamins, trace minerals, and other micronutrients. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 205.

National Institutes of Health website. Iodine: fact sheet for health professionals. ods.od.nih.gov/factsheets/Iodine-HealthProfessional/. Updated April 28, 2022. Accessed February 21, 2023.

Updated by: Stefania Manetti, RD/N, CDCES, RYT200, My Vita Sana LLC - Nourish and heal through food, San Jose, CA. Review provided by VeriMed Healthcare Network. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.