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Iodine: An In-Depth Guide to Its Potential Benefits


Story at-a-glance -

  • Iodine is found in foods, although it's also available in supplement form (potassium iodide or sodium iodide)
  • Read this article to learn more about iodine’s uses and health benefits, as well as foods rich in this mineral to help you prevent effects triggered by a low-iodine diet

By Dr. Mercola

Did you know that one of the most recognizable elements today was accidentally discovered? A French chemist named Bernard Courtois first learned about the existence of iodine in 1811, while helping his father manufacture saltpeter, an in-demand ingredient in gunpowder.

After burning seaweed he used as a source of potassium nitrate (instead of wood ash), he added too much sulfuric acid to the ashes. He then noticed a cloud of violet gas and saw that the vapor would condense into deep violet crystals on cold surfaces. Another French chemist named Joseph Louis Gay-Lussac was responsible for calling this element “iode,” from the Greek word ioeidēs meaning “violet-colored.”1

Keep reading this page to gain more knowledge about iodine’s uses and health benefits, as well as foods rich in this mineral to help you prevent effects triggered by a low-iodine diet.

What Is Iodine?

Iodine is found in foods, although it's also available in supplement form (potassium iodide or sodium iodide). Iodine may be added to multivitamin mineral supplements, while dietary supplements of iodine-containing kelp can be purchased too.2 Most of the world’s iodine supply is found in the ocean, where it’s concentrated in sea life, especially seaweed.3

There are multiple types of iodine. For starters, iodine, in the form of iodide, is made into two radioactive iodine forms: iodine-123 or I-123, and iodine-131 or I-131. Both are commonly used to address thyroid diseases. The former is harmless to thyroid cells, while the latter destroys them. Radioactive iodine is usually given orally in pill or liquid form.4 On the other hand, nascent iodine is rapidly absorbed and used by the body once it’s taken as a nutritional supplement.5,6

Do not confuse iodine with table salt. While the latter does contain iodine, it's technically sodium chloride. Povidone iodine isn't the same as typical iodine too.7 This substance, which is commonly known by the brand name Betadine, is used topically as an antiseptic.8

Insufficient amounts of iodine can cause the thyroid to function poorly and prompt feedback systems in the body to force it to work harder. To alleviate this, people can undergo an iodine test that’ll check the levels of this mineral in the body and see if they are deficient or not.9

Why Iodine Deficiency Is Alarmingly Rising

Iodine deficiency is a rising problem in the U.S. Average urinary iodine levels, considered a good measure of recent dietary iodine intake, have dropped by more than half since the 1970s. There are nutritional and environmental factors linked to this problem, namely:10

  • A negative change in diet: The average U.S. household does less home cooking and depends more on prepackaged and ready-to-eat foods, or meals in restaurants. Many prepackaged foods are high in salt, but this doesn’t automatically mean that they’re iodized and have enough iodine to meet the body’s needs.
  • Thiocyanates in commonly consumed foods: At high amounts, thiocyanates may interfere with iodine uptake into the thyroid gland. This makes it seem like a person has an iodine deficiency, when in reality they don’t. If you consume more iodine because you think you have a deficiency, this may lead to a harmful side effect. Foods like cassava, soy and Brassica family vegetables commonly contain thiocyanates.

There are also certain groups of people who may be at risk for an iodine deficiency:

  • Vegans: Fish and dairy are among the foods with the highest amounts of iodine.
  • Pregnant women: Expectant moms may need about 50 percent more iodine than other women, but surveys showed that many pregnant women in the U.S. are not getting enough iodine. However, experts are unsure if low iodine levels can affect their babies.
  • People living in regions with iodine-deficient soils who eat mostly local foods: These soils tend to produce crops with low iodine levels. Regions with the most iodine-poor soils include the Himalayas, the Alps and the Andes regions, as well as river valleys in South and Southeast Asia.
  • People who get marginal amounts of iodine and also eat foods containing goitrogens: Goitrogens interfere with the way the body uses iodine, and are found in soy and cruciferous vegetables like cabbage, broccoli, cauliflower and Brussels sprouts.

As mentioned earlier, iodine deficiency becomes a problem when the body fails to make sufficient amounts of the thyroid hormone. This can lead to negative effects like:11

  • Stunted growth, mental retardation and delayed sexual development in a baby (if a pregnant woman has severe iodine deficiency)
  • Lower-than-average IQ levels in infants and children
  • Reduced ability to work and think clearly among adults

There are many iodine deficiency symptoms to watch out for, such as:12

  • Swelling of the thyroid glands in the neck, causing the formation of a visible lump called a goiter
  • Cognitive issues like low IQ levels, trouble learning and mental disabilities (especially in children)
  • Hypothyroidism or low thyroid levels that can affect adults, infants and teens

An iodine deficiency can also trigger a rare but life-threatening hypothyroidism complication called myxedema. Warning signs include:13

  • An intense intolerance to cold temperatures
  • Drowsiness followed by extreme fatigue, and ultimately, unconsciousness

There are things that can trigger a myxedema coma among people with hypothyroidism, such as sedatives, an infection or other stressors on the body. Myxedema requires immediate medical treatment, so if you notice someone exhibiting symptoms, seek medical attention right away.

If you want to find out if you have sufficient iodine levels or not, you may undergo tests. When testing for an iodine deficiency, your doctor may recommend any of the following:14

  • Urine test: This is considered the simplest and fastest test, with results being ready in a few minutes. However, it’s not as accurate.
  • Blood test: A blood test is another simple and accurate test that’ll check for your body’s iodine levels, but it takes more time to read than a urine test.
  • Iodine patch test: Doctors will paint a patch of iodine on your skin and check how it looks 24 hours later. People who aren’t iodine deficient will notice that the patch fades no sooner than 24 hours. However, an iodine deficiency may likely cause the iodine to be absorbed into the skin more quickly. While this test isn’t the most accurate, it’s inexpensive and relatively quick.
  • Iodine loading test: This test measures how much iodine you excrete in your urine in a 24-hour period. A caveat of an iodine loading test is that this isn’t the fastest nor the most convenient test, mainly because you need to collect every urine sample you have in a 24-hour period.
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Iodine Rich Foods to Try

To correct iodine deficiency or help manage your levels, there are various foods high in iodine that you can add to your diet, namely:15

Sea vegetables like kelp, arame, hiziki, kombu and wakame: In particular, kelp is said to have the highest amount of iodine of any food on the planet.

Fresh and organic cranberries or cranberry juice: While these are a good source of iodine, consume fresh and organic cranberries moderately because they contain fructose. Meanwhile, try making your own cranberry juice or purchase juice that's certified 100 percent juice, and not a packaged drink that contains added sugar.

People with urinary tract stones must limit or avoid cranberry intake because these contain oxalic acid that can trigger development of more stones. The same principle applies to people taking warfarin (an anticoagulant medicine), because cranberries may enhance this medicine’s anticoagulant capacity.

Yogurt made from organic and grass fed milk: A natural source of both iodine and probiotics, organic and grass fed yogurt is an excellent addition to your diet.

Organic strawberries: Just like with cranberries, eat strawberries in moderation because of their fructose content. Eating too much strawberries can increase your fructose levels and put your health at risk.

Raw organic grass fed cheese: This type of cheese is high in iodine, with an ounce of raw cheddar cheese typically containing around 10 to 15 micrograms of iodine.

Iodine’s Uses and Health Benefits

Iodine is essential for the body's production of thyroid hormones that help control the body's metabolism and regulate important functions. Other health benefits linked to iodine include:16

  • Improved fetal and infant development: Pregnant and breastfeeding women must get enough iodine so their babies can grow and develop properly. Iodine can be found in breast milk. However, the iodine content in the breast milk typically depends on how much iodine the mother gets.
  • Improved cognitive function during childhood: Increasing iodine levels in children with mild iodine deficiency can help improve their reasoning abilities and overall cognitive function.
  • Decreased risk of radiation-induced thyroid cancer: The U.S. Food and Drug Administration has approved the use of potassium iodide as a thyroid-blocking agent that may help lower the risk of thyroid cancer in radiation emergencies. This can be crucial because nuclear accidents can release other forms radioactive iodine into the environment, and increase the risk of thyroid cancer in people exposed to the substance/s.

Throughout the years, iodine has also been used to:

Help prevent iodine deficiency and its consequences

Assist with treatment of cutaneous sporotrichosis, a skin disease caused by a fungus

Address fibrocystic breast disease

Aid with treatment of diabetic ulcers

Act as an expectorant

Help prevent eye disease, diabetes, heart disease and stroke

Eliminate fungi, bacteria and other microorganisms like amoebas

Purify water

Topical application of iodine may be helpful in killing germs and preventing chemotherapy-caused mucositis, or soreness inside the mouth. Lastly, as mentioned earlier, iodine, particularly potassium iodide may be used during a radiation emergency to protect the thyroid gland against radioactive iodides.17

Studies on Iodine

In general, studies regarding iodine have yielded mixed results. These studies focused on iodine’s positive impacts:

  • Reduced risk of a cardiovascular disease like hypercholesterolemia: This study published in The Journal of Nutrition in September 2015 suggested that iodine prophylaxis may decrease cardiovascular disease risk among overweight adults, and that iodine supplementation reduced prevalence of hypercholesterolemia among overweight women with a moderate to severe iodine deficiency.18
  • Effects on non-central recurrence of cervical cancer: An October 2017 Oncology Letters study revealed that seed implantation of iodine-125, a type of iodine, can be utilized as a complementary treatment for recurrent cervical cancer.19

If you need more information regarding the importance of having enough iodine in your body, take note of these studies that highlighted the negative impacts brought about by an iodine deficiency:

  • Impaired child neurodevelopment: A July 2017 study in The Journal of Nutrition discovered that maternal iodine intake below the Estimated Average Requirement during pregnancy was linked to symptoms of child language delay, behavior problems and reduced fine motor skills at 3 years of age.20
  • Increased risk for thyroid cancer: Results from this study, published in Thyroid Research on June 2015, suggested that an iodine deficiency is a possible risk factor for thyroid cancer. An iodine deficiency was also said to raise the risk for follicular thyroid cancer (FTC) and possibly, anaplastic thyroid cancer (ATC).21

Unfortunately, iodine supplementation may not always be the solution to some concerns, especially child neurodevelopment:

  • According to this December 2015 Trials article, iodine supplementation during a pregnancy didn’t lead to better childhood neurodevelopment.22
  • In this study published in The Lancet, Diabetes & Endocrinology on November 2017, researchers concluded that daily iodine supplementation in mildly iodine-deficiency pregnant women had no effect on child neurodevelopment between ages 5 to 6 years old.23

What’s the Ideal Dosage of Iodine?

The amount of iodine you need daily depends on your age, as emphasized by the National Institutes of Health:24

Age Groups Recommended Daily Amount of Iodine
Birth to 6 months 110 mcg
Infants (7 to 12 months) 130 mcg
Children (1 to 8 years) 90 mcg
Children (9 to 13 years) 120 mcg
Teens (14 to 18 years) 150 mcg
Adults 150 mcg
Pregnant teens and women 220 mcg
Breastfeeding teens and women 290 mcg

However, there may be instances when you may need to get more iodine than what is typically recommended for your age group. As mentioned earlier, iodine deficiency is rampant in the U.S. today, and some of these amounts may not be enough to combat this major health problem.

Do You Have an Iodine Allergy?

Some people may be intolerant to substances closely mixed together with iodine. While adverse reactions or allergies to iodine are rare, they can be fatal.25 Exposure to items that contain traces of iodine can trigger any of the following reactions among hypersensitive people:26

  • Contact dermatitis, or an itchy rash that comes on slowly
  • Urticaria or hives
  • Anaphylaxis, or a sudden allergic reaction that can cause hives, swelling of the tongue and throat, and shortness of breath

Iodine Side Effects to Watch Out For

Elevated iodine levels can trigger some of the same symptoms as an iodine deficiency, such as an enlarged thyroid gland or goiter and thyroid gland inflammation, and may potentially lead to a higher risk of thyroid cancers like thyroid papillary cancer or thyroid follicular cancer. Taking iodine supplements over a prolonged period of time may also lead to hypothyroidism by blocking thyroid production.

A life-threatening complication of elevated iodine levels called thyrotoxicosis may also develop, causing fever, confusion, rapid heartbeat and other abnormal irregular heartbeats, and congestive heart failure. Should you or someone you know develop these indicators while taking iodine supplements, seek medical care immediately. Other side effects of getting a very large dose of iodine include:

Burning feeling in the mouth, throat and stomach Fever Stomach pain
Nausea Vomiting Diarrhea (sometimes bloody)
Weak pulse Coma Discoloration of teeth

People with a hypersensitivity reaction to iodine may notice a metallic taste, burning in the throat, or may feel soreness on the teeth or gums. This can be dangerous because swelling that eventually occurs in the throat may cause asphyxiation. Iodine supplements may also interact or interfere with medicines:

  • Anti-thyroid medicines like Methimazole (Tapazole): This is used to treat hyperthyroidism. Iodine supplements may interact with anti-thyroid medications and may potentially cause the body to produce too-little amounts of the thyroid hormone.
  • ACE inhibitors like benazepril (Lotensin), lisinopril (Prinivil and Zestril) and fosinopril (Monopril): ACE inhibitors are usually recommended for people with high blood pressure levels. If you take iodine supplements alongside ACE inhibitors, there’s a risk that the potassium in your blood rises to an unsafe level.
  • Potassium-sparing diuretics like spironolactone (Aldactone) and amiloride (Midamore): If you take potassium iodide supplements, the amount of potassium in your blood can reach very high levels if you take these alongside potassium-sparing diuretics.

If you want to reduce the bitter taste normally found in iodine supplements, you can dilute the medicine in juice or milk. Lastly, if you’re interested in taking iodine supplements but are taking certain dietary supplements and medicines, inform your doctor about it. They may advise whether your current supplements or medicines may interact with the iodine supplements or how your body absorbs, uses or breaks down other nutrients.27,28

Iodine Is Truly an Effective Mineral for Your Health

Iodine is crucial in maintaining ideal health and well-being, but the sad reality is that most people take iodine for granted and don’t monitor their daily intake of this mineral. This leads to a problem like iodine deficiency, which affects many people in the U.S. nowadays.

You can alleviate an iodine deficiency before it’s too late by eating iodine-rich foods and/or taking high-quality supplements and multivitamins containing iodine. On a final note, be careful about raising your iodine intake, because there are numerous side effects, some of which are life-threatening, that can worsen a person’s condition.

Frequently Asked Questions (FAQs) About Iodine

Q: What does iodine do?

A: These health benefits show why your body needs iodine:

Helps produce vital thyroid hormones

Assists with boosting fetal and infant neurodevelopment

Helps improve cognitive function during childhood

Lessens risk for radiation-induced thyroid cancer

Q: What is iodine used for?

A: Iodine has many known uses. Here are some, to name a few:

Acting as an expectorant

Eliminating fungi, bacteria and other microorganisms like amoebas

Purifying water

Addressing fibrocystic breast disease

Assisting with treatment of cutaneous sporotrichosis, a skin disease caused by a fungus

Q: Is iodine a metal?

A: According to Livescience, iodine is a nonmetal, although it does exhibit some metallic qualities.

Q: Where do you get iodine?

A: You can increase your body’s iodine stores by consuming iodine-rich foods, or taking high-quality supplements or multivitamins containing this mineral.

Q: What foods have iodine?

A: Iodine-rich foods you can add to your diet include sea vegetables like kelp, fresh and organic cranberries or cranberry juice, and grass fed yogurt and cheese.

Q: Does sea salt have iodine?

A: Most brands of sea salt aren’t iodized. However, sea salt, which can be available in fine or coarse crystals, often contains traces of calcium, magnesium and potassium.29

Q: Is iodine poisonous?

A: Iodine can be poisonous and may deliver side effects if you take more than the recommended daily amount. Before taking iodine supplements or increasing your intake of iodine-rich food, talk to a doctor first to know about the amount of iodine you should be taking and to prevent adverse effects in the long run.

Q: How much iodine do I need?

A: According to the National Institutes of Health, the amount of iodine that you need typically depends on your age.