Table of ContentsView AllTable of ContentsThe Importance of IodineHow Much Iodine You NeedIodine SourcesIodine DeficiencyExcess IodineFrequently Asked Questions
Table of ContentsView All
View All
Table of Contents
The Importance of Iodine
How Much Iodine You Need
Iodine Sources
Iodine Deficiency
Excess Iodine
Frequently Asked Questions
Iodineis an element that’s required for the thyroid gland to producethyroid hormones. Since the body does not produce iodine on its own, it needs to come from dietary sources—and striking the right balance is key. Inadequate levels or overconsumption of iodine can lead to or worsen thyroid disease, as well as cause other significant health concerns.
When you consume iodine, it is quickly absorbed and entered into your bloodstream. Your thyroid, which has tiny cells that capture the circulating iodine, takes in and oxidizes it so it can begin to be used to create triiodothyronine (T3) and thyroxine (T4)—thyroid hormones that make their way throughout the body to regulate metabolism and ensure healthy functioning of the heart, brain, and other organs. While the major portion of iodine is concentrated in the thyroid gland, the nonhormonal iodine is found in a variety of body tissues including the mammary glands, the eyes, the gastric mucosa, the cervix, and the salivary glands.
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This can occur for a number of reasons, including taking in too little or too much iodine.
According to the Food and Nutrition Board of the National Academies (formerly the National Academy of Science), the recommended dietary allowance (RDA) for iodine in the United States ranges anywhere from 90 mcg per day for toddlers to 150 mcg for teens and adults.
Considering that one cup of plain low-fat yogurt contains about 75 mcg, 3 ounces of fish sticks contain about 54 mcg, a cup of cooked pasta contains about 27 mcg, and a quarter teaspoon of iodized salt contains about 71 mcg, that’s generally an easy amount for most people to consume.
Pregnant and Breastfeeding Women
The American Thyroid Association recommends that all pregnant and breastfeeding women in the United States and Canada take a prenatal vitamin containing 150 mcg of iodine a day as part of an overall recommended intake of 220 mcg/day and 290 mg/day, respectively. Excess iodine, however, can be particularly dangerous in these women.
Most Americans have no trouble meeting the recommended intake of iodine because of the iodization of salt in the United States and incorporation of iodine-rich foods such as the following:
Supplements (e.g. potassium iodide, sodium iodide, kelp) and iodine-containing herbs, such as bladderwrack, are other sources that can be considered.
Health Benefits and Uses of Iodine
Since iodine is needed to make thyroid hormone, diminished levels can lead tohypothyroidism(low thyroid function).Iodine deficiencyis also linked to the development ofgoiter(thyroid enlargement).
The impact of too little iodine reaches further. Children born to mothers with severe iodine deficiency can suffer from stunted growth, severe and irreversible intellectual disabilities, and problems with movement, speech, and hearing.
Even mild iodine deficiency during pregnancy can lead to subtle intellectual deficits, although many children improve with iodine supplementation. Mild iodine deficiency can also cause miscarriage.
Risk Factors
Research suggests that 35% to 45% of the world’s population is iodine deficient.At a global scale, roughly 2 billion people are classified as having iodine deficiency, of which around 50 million have clinical symptoms.
To address this global concern, 124 countries have instituted legislation for mandatory salt iodization as of 2022, resulting in 88% of the world’s population having access to iodized salt on grocery store shelves.
Even so, 21 countries have insufficient iodine in their diets, according to research from the Iodine Global Network. These not only include developing countries like Madagascar, Mali, Cambodia, Haiti, Lebanon, and Tajikistan, but also developed countries like Norway, Israel, Finland, and Germany.
The risk of iodine deficiency in the United States has long been considered small due to the implementation of salt iodization starting back in the 1920s. However, recent research suggests that mild-to-moderate iodine deficiency is, in fact, common in the U.S. and appears to be increasing.
According to data from the ongoing National Health and Nutrition Examination Survey (NHANES), no less than 38% of the U.S. population had a urine iodine concentration (UIC) of under 100 in 2012, meaning that they met the definition of being iodine deficient.
There are certain risk factors that may account for such deficiencies, not only in the United States but other developed and developing countries:
At the same time, there has been an increased demand among consumers for sea salt, which is naturally low in iodine. As a result, only 53% of table salt sold in the United States is iodized.
Betadine vs. Iodine: What’s the Difference?
Preventive Supplementation When You Have Thyroid Disease
Some healthcare providers are almost knee-jerk in their insistence that anyone with a thyroid problem requires iodine supplementation; alternative healthcare providers may recommend iodine-containing herbs, like kelp orseaweed.
This can be particularly risky, in part because iodine supplements can interact with several types of drugs, including anti-thyroid drugs used to treat hyperthyroidism.Taking high doses of iodine with anti-thyroid medications can have an additive effect and could cause hypothyroidism.
If iodine deficiency isn’t the cause of hypothyroidism, then iodine supplements won’t be helpful.
You’ll want to be very careful about upping your iodine intake unless you and your healthcare provider have some very strong evidence that you’re deficient. This is especially true if you’re pregnant or planning to become pregnant.
Given the strong link between iodine and thyroid health, it’s reassuring to learn that iodine deficiency is rare in the United States and other developed countries where iodized salt is used. Indeed, as anInternational Journal of Molecular Sciencesstudy reported in 2014, iodine excess is currently a more frequent occurrence in these places. This, though, is not without concern.
For some people with abnormal thyroid glands, excessive iodine can trigger or worsen hypothyroidism. While initially, you may have more energy, high doses can cause an “iodine crash” that leaves you feeling exhausted and achy within a few days.
In addition, large amounts of iodine block the thyroid’s ability to make thyroid hormones. A 2014 study in the journalEndocrinology and Metabolismfound that more-than-adequate or excessive iodine levels are unsafe and may lead to hypothyroidism and autoimmune thyroiditis (Hashimoto’s thyroiditis, chroniclymphocytic thyroiditis), especially for people with recurring thyroid disease.
Women who take too much supplemental iodine during pregnancy may give birth to babies with congenital hypothyroidism, a thyroid deficiency that, if left untreated, can lead to mental, growth, and heart problems, according to a 2012 study published inThe Journal of Pediatrics.
While iodine poisoning is rare, the overconsumption of iodine can be just as problematic as consuming too little.
Are You Getting Enough or Too Much?
While iodine can be detected in urine, relying on such a test is not helpful, since 90 percent of the iodine you ingest is quickly expelled. Rather, healthcare providers use thyroid tests to determine if your iodine intake is concerning or not.
In addition, iodine deficiency is typically suspected based on the development of goiter, hypothyroidism, orcongenital hypothyroidism(low thyroid function at birth).
Iodine is important for the production of the thyroid hormones triiodothyronine (T3) and thyroxine (T4). The body does not make iodine, so it needs to come from dietary sources. Fortunately, it is not hard to get enough iodine in your diet thanks to the iodization of table salt.
Iodine is found in animal protein, sea vegetables, iodized table salt, and fortified foods. Common sources are seaweed, tuna fish, oysters, shrimp, dairy products, eggs, chicken, and beef liver.
14 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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