The Health Benefits of Iodide

What is iodide and is it different from potassium iodide?

Closeup of a spoonful of salt

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Iodide and iodine are different expressions of the same element. Iodide is the ion state of iodine (the reduced form of iodine). It occurs when iodine bonds with another element, such as potassium (in which case it is considered potassium iodide). You cannot ingest iodine in the iodine state. This can be very confusing because you'll often hear the terms iodine and iodide being used interchangeably. You can find iodide naturally present in certain foods, added to others, and in supplement form.

Also Known As

  • Atomic number 53
  • Iodized salt
  • Potassium iodide
  • Povidone iodine
  • Saturated solution potassium iodide
  • Sodium iodide
  • Sodium iodine

Health Benefits

According to the National Institute of Medicine, "Iodine in food and iodized salt is present in several chemical forms including sodium and potassium salts, inorganic iodine (I2), iodate, and iodide, the reduced form of iodine. Iodine rarely occurs as the element, but rather as a salt; for this reason, it is referred to as iodide and not iodine. Iodide is quickly and almost completely absorbed in the stomach and duodenum."

The health benefits of iodide are the same as iodine. Iodide plays a role in:

  • Fetal development
  • Thyroid hormone regulation
  • Metabolism regulation

You need to consume iodide in your diet because it is an essential mineral involved in the production of thyroid hormones. Thyroid hormones play a role in metabolism and growth. Iodine deficiency may lead to goiter, hypothyroidism, poor growth, and neurocognitive impairments.

Possible Side Effects

Excessive amounts of supplemental iodide can result in the same symptoms as iodine deficiency. This can include iodine-induced hyper- or hypothyroidism and goiters. People at increased risk are young children and those with thyroid conditions.

Excessive amounts of iodide intake can also result in iodine poisoning. Symptoms of poisoning can range from mild to severe and may include:

  • Abdominal pain
  • Coughing
  • Delirium
  • Diarrhea, sometimes bloody
  • Fever
  • Gum and tooth soreness
  • Loss of appetite
  • Metallic taste in the mouth
  • Mouth and throat pain and burning
  • No urine output
  • Rash
  • Salivation (producing saliva)
  • Seizures
  • Shock
  • Shortness of breath
  • Stupor (decreased level of alertness)
  • Thirst
  • Vomiting

Dosage and Preparation

If you have an iodine deficiency, are pregnant or lactating (in which case your iodide needs increase), or are a young child with a limited diet, supplementing may be indicated, but should always be monitored by a physician.

According to the National Institute of Health, "Many multivitamin/mineral supplements contain iodine in the forms of potassium iodide or sodium iodide. Dietary supplements of iodine or iodine-containing kelp (a seaweed) are also available. A small study found that potassium iodide is almost completely (96.4%) absorbed in humans."

You can check your multivitamin and mineral supplement to determine if it contains iodide and in what form. You can also determine if it provides the recommended daily allowance (RDA) by checking the percent daily value. If your multivitamin states that it contains 100% of the daily value, then your daily needs are covered.

Supplementing with Potassium Iodide

Potassium iodide (KI) is a salt form of iodine that has been used to help block radioactive iodine from being absorbed by the thyroid gland, thus protecting people from radiation-induced thyroid cancer. This type of iodide is also found in multivitamin/mineral supplements, as well as over-the-counter supplement form (liquid and pill).

In instances where radioactive iodine is released into the environment, as a result of a nuclear accident or explosion, it may be recommended to supplement with potassium iodide to prevent thyroid cancer. Thyroid accumulation of radioactive iodine can increase the risk of thyroid cancer, especially in children. Additionally, those persons who are iodine deficient are at even greater risk.

The administration of pharmacologic doses of potassium iodide is usually prescribed by a physician within 48 hours of exposure and can decrease the risk of thyroid cancer by reducing the amount of radioactive iodine the thyroid takes in. It is not guaranteed that consumption will absolutely prevent thyroid cancer, but in the past, it has been determined that it does decrease the risk. It is also important to note that the Food and Drug Administration (FDA) states, "It is not a general radioprotective agent."

The Center for Disease Control advises that people should take potassium iodide only when advised by a public health or emergency management official. The reason for this is because careful monitoring is needed to prevent iodine toxicity.

Some people use potassium iodide to prevent and treat thyroid disorders, but before doing so it's important to discuss this with your healthcare provider to avoid any potential side effects or medical issues.

What to Look For

Iodide is found naturally in certain foods such as:

  • Iodized salt
  • Seafood and sea products (fish, shellfish, seaweed varieties, and seaweed-based products)
  • Certain fruits and vegetables, such as potato with the skin (but the amount varies depending on the soil)
  • Beans
  • Dairy products of any kind (kefir, milk, cheese, yogurt, butter, ice cream)
  • Egg yolks or whole eggs, and foods containing whole eggs
  • Bakery products containing iodine/iodate dough conditioners or high-iodine ingredients

When choosing a supplement, look for a multivitamin that contains the RDA of iodine. You can ask your pharmacist for recommendations; there are many over-the-counter multivitamin supplements to choose from.

When To Avoid Iodide

People who are allergic to iodide, who have certain health conditions, or require certain health interventions and medications should avoid supplementing with iodide.

Treatment of thyroid cancer: If you have thyroid cancer and have been treated with radioactive iodine or if you are having further testing which includes whole-body radioiodine scans using a tracer, you may have been told to follow a low-iodine diet. Your health care provider should educate you on a short-term low-iodine diet.

Certain medicines interact with iodide: When taking certain medications such as Cordarone (amiodarone), which contains iodine, supplementing with iodide can result in too much iodine in the blood. Additionally, people on medication for an overactive thyroid should probably avoid iodide supplementation. Taking potassium iodide along with some medications for high blood pressure or diuretics might cause too much potassium in the body. Excess amounts of potassium can be problematic. Therefore, be sure to go over your medication list thoroughly with your health care provider before starting any type of iodide supplementation.

Other Questions

Do fruits and vegetables contain iodide? Yes, some fruits and vegetables contain small amounts of iodide, but the amount will vary based on how much iodide is in the soil. For example, one medium potato with the skin contains about 60 micrograms (ug) of iodide, which accounts for a little less than half of an adults 150 micrograms daily requirement.

I have iodine-deficiency hypothyroidism, I was told I need to avoid goitrogens, what are those? Goitrogens are substances found in food that can interfere with the way the body uses iodine. Some foods that contain these include cruciferous vegetables, like broccoli and cabbage as well as soy, millet, and cassava. Cooking cruciferous vegetables, gentle steaming or sautéing, can reduce the amount of goitrogens. Discussing your diet with a medical professional will be beneficial. They may recommend you get your iodine levels tested to make sure you are in fact deficient.

A Word From Verywell

Iodine is an essential mineral necessary for health and development. Iodide is the reduced form of iodine that is found in foods, supplements, and salt. Oftentimes you'll hear these words used interchangeably which can be very confusing.

Understanding what they are and how they differ can help you recognize sources, requirements, and benefits. Potassium iodide has been used as a supplement in the prevention of thyroid cancer in people who have been exposed to radioactive iodine.

Whether or not you need to supplement with a form of iodide will depend on your diet, health, access to iodine, and stage of life. Iodide is particularly important for children and pregnant women because of its role in growth, metabolism, and development.

Most people can get adequate amounts of iodide from iodized salt, however, if you are unsure if you need more iodide in your diet, ask your physician before beginning to supplement on your own. Supplementing with too much can lead to adverse effects and can be dangerous.

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Article Sources

  1. Office of Dietary Supplements - Iodine. NIH Office of Dietary Supplements. National Institutes of Health. Updated July 09, 2019.

  2. Center for Drug Evaluation and Research. Frequently Asked Questions on Potassium Iodide (KI). U.S. Food and Drug Administration. Published October 14, 2016.

  3. Facts About Potassium Iodide (KI) | Radiation and Your Health. Centers for Disease Control and Prevention. Updated April 4, 2018.

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