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Iodine Natural Food Sources for Optimum Health and Protection

by Ralph Teller

Iodine Facts and Health Benefits

Thyroid Health. Iodine is an essential component of certain thyroid hormones that regulate many important biochemical reactions, including protein synthesis and enzymatic activity, and are critical to metabolic activity. These Iodine dependent Thyroid hormones are also required for proper skeletal and central nervous system development in fetuses and infants. Iodine also appears to play a role in immune response.

Radiation Emergency. Radioactive iodine is a by-product in many nuclear reactors. Iodine is used in the event of radiation emergencies, to protect the thyroid gland against radioactive iodides. Intake of Potassium Iodide tablets is recommended for use in a radiation emergency. However, potassium iodide should only be used in a radiation emergency, not in advance of an emergency to prevent sickness.For example, The Royal Society of Chemistry is warning against panic buying of Potassium Iodide tablets as a protective agent against exposure to radioactive iodine, where there is no actual radiation exposure.

Why does Potassium Iodide Work as an Agent to Protect the Thyroid in a Nuclear Emergency? Iodine is absorbed by the human body into the bloodstream where it is taken up by the Thyroid for hormone production. Exposure to a radioactive isotope of iodine from a nuclear hazard, and subsequent concentration in the Thyroid, can therefore result in damage to the thyroid. It is thought that by ingesting Potassium Iodide tablets, a high dose of non-radioactive iodine can overwhelm the natural iodine uptake mechanisms and so reduce the amount of radioactive iodine that might reach the thyroid. Taking Potassium Iodide tablets after exposure to radioactive iodine will still have some protective effect.

Protective Agent. Some physicians suggest Iodine is a trigger mechanism for apoptosis (the natural death of cells) and the main surveillance mechanism for abnormal cells in the body. Iodine triggers the death of cells which are abnormal or which have normal programmed death as part of their life cycle. This is part of a general theme that Iodine and a Thyroid hormone act as a team to provide constant surveillance against abnormal cell development, chemicals that are carcinogenic, and the spread of cancer in the body.

Natural Food Sources of Iodine

As the body cannot synthesize Iodine, this trace element must be obtained through the diet. In general, it is best to obtain Iodine from natural food sources. Seaweed (such as kelp, nori, kombu, and wakame) is one of the best food sources of iodine. Other good sources include seafood, dairy products and eggs. Iodine is also present in human breast milk. Fruits and vegetables contain iodine, the amount of which varies depending on the soil's iodine content. Here is a list of natural food sources of Iodine.

Selected Food Sources of Iodine (Source: NIH , DV = Daily Value per FDA)
Micrograms (mcg)
per serving
Percent DV*
Seaweed, whole or sheet, 1 g16 to 2,984 11% to 1,989%
Cod, baked, 3 ounces9966%
Yogurt, plain, low-fat, 1 cup7550%
Iodized salt, 1.5 g (approx. 1/4 teaspoon)7147%
Milk, reduced fat, 1 cup5637%
Fish sticks, 3 ounces5436%
Bread, white, enriched, 2 slices4530%
Fruit cocktail in heavy syrup, canned, 1/2 cup4228%
Shrimp, 3 ounces3523%
Macaroni, enriched, boiled, 1 cup2718%
Egg, 1 large2416%
Tuna, canned in oil, drained, 3 ounces1711%
Corn, cream style, canned, 1/2 cup149%
Prunes, dried, 5 prunes139%
Cheese, cheddar, 1 ounce128%
Raisin bran cereal, 1 cup117%
Lima beans, mature, boiled, 1/2 cup85%
Apple juice, 1 cup75%
Green peas, frozen, boiled, 1/2 cup32%
Banana, 1 medium32%

Iodine Recommended Daily Intake

The National Academies in 2001 established a RDA of Iodine for adult men and women of 150 mcg/day. However, the recommended intake for iodine during pregnancy is 220 mcg/day and during lactation is 290 mcg/day. In most people, iodine intakes from foods and supplements are unlikely to exceed the Upper Intake Levels. Long-term intakes above the Upper Intake Levels increase the risk of adverse health effects. The Upper Intake Levels do not apply to individuals receiving iodine for medical treatment under the care of a physician.

Tolerable Upper Intake Levels (ULs) for Iodine
Birth to 6 monthsNot possible to establish*Not possible to establish*  
7–12 monthsNot possible to establish*Not possible to establish*  
1–3 years200 mcg200 mcg  
4–8 years300 mcg300 mcg  
9–13 years 600 mcg600 mcg  
14–18 years900 mcg900 mcg900 mcg900 mcg
19+ years1,100 mcg1,100 mcg 1100 mcg 1100 mcg

Iodine Deficiency and Iodine Toxicity

Iodine Deficiency. Populations living in areas with poor access to marine-derived foods, whose drinking water has a low iodine content, or whose diet primarily contains foods grown in iodine-deficient soils are at risk for developing iodine deficiency. Goiter associated with iodine deficiency is common globally. Cretinism—a severe irreversible condition of diminished physical and mental growth following maternal and fetal iodine deficiency.

Goiter and Cretinism, along with hypothyroidism, test scores indicating low cognitive ability, and other developmental and growth disorders, are Iodine Deficiency Diseases. Data from 1994 to 2006 suggest that almost 2 billion people, or about one-third of the world population, are iodine deficient, including 98 million individuals in the Americas. While severe iodine deficiency is uncommon in the U.S., there is concern for some subgroups of reproductive-age women who do not consume dairy products. Iodine deficiency is the main cause of preventable childhood brain damage and a major public health problem throughout the world.

Iodine Toxicity As Iodine supplements combined with other medications may cause serious adverse reactions, it is recommended not to combine these medications without physician consent. Also, considering toxicity concerns in general, it's recommended to consult a physician before taking Iodine supplements.

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Articles on Iodine

Iodine, MedlinePlus, National Institute of Health

Dietary reference intakes (DRIs): Recommended dietary allowances and adequate intakes, elements, Food and Nutrition Board, Institute of Medicine (2011)

PublicationIodine and Radiation, David Bradley,

PublicationNatural Food Sources of Iodine, by Norma Chew, Livestrong

PublicationIodine Nutrition and the Impact of Dietary Sodium Reduction, Andrea F. Fus, PharmD, United States Food and Drug Administration, US Pharmacist

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