Recommended Dietary Allowance (RDA) for Iodine
Life Stage Age Males (μg/day) Females (μg/day)
Infants 0-6 months 110 (AI) 110 (AI)
Infants 7-12 months  130 (AI)  130 (AI)
Children 1-3 years 90 90
Children 4-8 years 90 90
Children 9-13 years 120 120
Adolescents 14-18 years 150 150
Adults 19 years and older 150 150
Pregnancy all ages 220
Breast-feeding all ages 290
Some Food Sources of Iodine
Food Serving Iodine (μg)
Salt (iodized) 1 gram 77
Cod 3 ounces* 99
Shrimp 3 ounces 35
Fish sticks 2 fish sticks 35
Tuna, canned in oil 3 ounces (½ can) 17
Milk (cow’s) 1 cup (8 fluid ounces) 99
Egg, boiled 1 large 12
Navy beans, cooked ½ cup 32
Potato with peel, baked 1 medium 60
Turkey breast, baked 3 ounces 34
Seaweed ¼ ounce, dried Variable; may be greater than 4,500 μg (4.5 mg)


Over-the-counter iodine supplements

Potassium iodide is available as a nutritional supplement, typically in combination products, such as multivitamin/mineral supplements. Iodine makes up approximately 77% of the total weight of potassium iodide (56). A multivitamin/mineral supplement that contains 100% of the daily value (DV) for iodine provides 150 μg of iodine. Although most people in the US consume sufficient iodine in their diets (see Sources), an additional 150 μg/day is unlikely to result in excessive iodine intake. The American Thyroid Association (ATA) recommends prenatal supplementation with 150 μg/day of iodine and advises against the ingestion of ≥500 μg/day of iodine from iodine, potassium iodine, and kelp supplements for children and adults, and during pregnancy and lactation (see also Safety(3674).

Iodine fortification programs

The fortification of salt with iodine is a feasible and inexpensive method to eliminate iodine deficiency, and salt iodization programs have been implemented in almost all countries. In North America, salt fortification with iodine is mandated in Canada and some parts of Mexico, but only voluntary in the US such that only 52% of US table salt is iodized and only one-fifth of the total salt consumed in the US is iodized (72, 75). Potassium iodide (KI), cuprous iodide (CuI), and potassium iodate (KIO3) are used to iodize salt. The US Food and Drug Administration (FDA) recommends between 46 and 76 μg of iodine per gram of salt in iodized salt. However, the recent analysis of 88 US iodized food-grade salt samples revealed that the iodine content was below the recommended range in 52% of the samples and above the range in 7% of the samples (76).

In other countries, salt commonly contains 20-50 μg of iodine per gram of salt, depending on local regulations (76). In countries like Denmark (77), Australia (78, 79), and New Zealand (80), the use of iodized salt in the bread-making process is mandated. Additional approaches have been explored, including sugar fortification (81), egg fortification (82), use of iodized salt in the preparation of fermented fish and fish sauce (83), and use of iodine-rich crop fertilizers (84). In addition, fortification of livestock feeds with iodine and the use of iodophors for sanitation during milking contribute to increasing iodine content in dairy products (85). Finally, annual doses of iodized vegetable oil are administered orally or intramuscularly to individuals in iodine-deficient populations who do not have access to iodized salt (456).


Acute toxicity

Acute iodine poisoning is rare and usually occurs only with doses of many grams. Symptoms of acute iodine poisoning include burning of the mouth, throat, and stomach, fever, nausea, vomiting, diarrhea, a weak pulse, cyanosis, and coma (1).

Excessive iodine intakes

Risk of iodine-induced hyperthyroidism in iodine-deficient individuals
  • Iodine supplementation programs in iodine-deficient populations have been associated with an increased incidence of iodine-induced hyperthyroidism (IIH), especially in older people with multi-nodular goiter (86). Iodine intakes of 150-200 μg/day have been found to increase the incidence of IIH in iodine-deficient populations. Iodine deficiency increases the risk of developing autonomous thyroid nodules that are unresponsive to TSH control (see Function). These autonomous nodules may then overproduce thyroid hormones in response to sudden iodine supply. IIH symptoms include weight loss, tachycardia (high pulse rate), muscle weakness, and skin warmth. IIH can be dangerous in individuals with underlying heart disease. Yet, because the primary cause of nodular goiter and IIH is chronic iodine deficiency, the benefit of iodization programs largely outweighs the risk of IIH in iodine-deficient populations (1).