One of the most famous food pairings? It’s not PB&J, butter and popcorn, or tomato soup and grilled cheese: It’s iodine and salt.

Yep, iodine---a trace element---was found to be so important for thyroid function that table salt was fortified with iodine and sold in US grocery stores starting in the 1920s in order to combat iodine deficiency. More than 100 countries also iodize their salt. But does this connection mean you should stock up on iodine supplements if you suspect (or know) your thyroid hormones are out of whack? Let’s explore the answer.


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First, what does iodine have to do with thyroid function?

Your thyroid---a small butterfly-shaped gland that sits at the base of your neck---is a master regulator of your body. Iodine is used by the body to produce thyroxine (T4) and triiodothyronine (T3), two thyroid hormones, according to the National Institutes of Health (NIH).

Overall, your thyroid hormones control your metabolism, which in turn, affects how your heart, muscle, and digestion work, according to the Society for Endocrinology. As a result, a poor functioning thyroid can cause weight fluctuations (up or down), mood problems, sleep issues, or an intolerance to heat or cold. Some people with thyroid dysfunction, called hypothyroidism or hyperthyroidism, develop an abnormally enlarged thyroid, also called a goiter.

Because your body does not make this element on its own, you have to get iodine from your diet in some way. In addition to iodized table salt, the mineral is also found naturally in some foods, such as seaweed, fish (like cod), oysters, plain Greek yogurt, and enriched bread, notes the NIH.

Can an iodine deficiency cause thyroid problems?

Yes, if you don’t have enough iodine, your body will struggle to make the thyroid hormones you need, and that can lead to hypothyroidism (an underactive thyroid gland) or, conversely, even hyperthyroidism (an overactive thyroid gland), according to a review in The Lancet Diabetes & Endocrinology. Though most people in the US are not at risk for thyroid deficiency, nearly one-third of people around the world do not get enough, according to the American Thyroid Association (ATA). The organization points out that mild iodine deficiency has cropped up in people who are pregnant.

Symptoms of an iodine deficiency include all of the symptoms of hypothyroidism, which is essentially when the body slows down. You might have mild weight gain, become constipated, deal with dry skin, and feel like your mood is blah, notes the ATA. Your thyroid gland may become enlarged (a goiter). If you’re trying to get pregnant, severe iodine deficiency makes you more prone to miscarriage or having a baby with congenital abnormalities and intellectual disabilities.

Do iodine supplements help or hurt thyroid issues?

In most cases, iodine supplements are not necessary, according to Mayo Clinic. Taking these can also harm your thyroid, especially if you don’t need them in the first place. While not enough iodine stymies the gland’s ability to produce those all-important thyroid hormones, excessive intake also thwarts this process.

In addition, research shows that taking excessive iodine is a risk factor for developing Hashimoto’s thyroiditis, an autoimmune disorder that’s responsible for the majority of cases of hypothyroidism. Having too much iodine may trigger the production of antibodies that damage the organ.

If you have thyroid cancer, you also wouldn’t take iodine. In that instance, doctors likely recommend following a low-iodine diet, which includes less than 50 micrograms of iodine daily, before receiving certain treatments, according to Memorial Sloan Kettering Cancer Center.

Though it’s always scary to talk about thyroid cancer---in 2022 there will likely be about 44,000 thyroid cancers diagnosed, the majority in women---it’s one reason why health professionals encourage people to check their neck to detect a possible thyroid problem.

If you do detect a bulge or protrusion in the area of your thyroid gland, you should not self-treat with iodine. Rather than jumping in to take an iodine supplement, you want to get the proper diagnosis at the doctor, which is done through blood tests to analyze thyroid function. Together, you can then talk about the right treatment for you.

Iodine is a bona fide treatment to reduce the size of a goiter---but only if that goiter happened because you don’t get enough of the mineral in the diet, which in the US is unlikely. Otherwise, your doctor will treat you for hypothyroidism or hyperthyroidism (depending on your issue), which is typically done with medication and can help shrink the goiter and normalize your hormone levels.

Getting to the bottom of your thyroid issues

First, it’s important to back up and see if you can accurately screen for iodine deficiency. And the answer is…not really. The ATA notes that blood and urine tests are not accurate for making a diagnosis.

Rather than focusing on iodine levels specifically, you can get your thyroid hormone levels tested. Certainly, this can be done through your doctor. For an at-home option, there’s specifically a Thyroid Hormones Test, which will screen for T3, T4, and TSH levels. (TSH stimulates the thyroid to produce T4 and T3.)

You may want to focus on thyroid hormone testing if you could possibly be falling short of consuming enough iodine in your diet. That includes if you’re pregnant, are vegan, or shy away from using iodized salt or eating products that are made with iodized salt. Keep in mind that not all salt is iodized---if you purchase kosher salt or fancy sea salts, these won’t contain iodine.

Prevention is also key if you’re pregnant. Two things you can do here: One, get your thyroid levels checked if you are considering getting pregnant or already have a little one on the way, advises the American Society for Reproductive Medicine. Two, if you are planning on becoming pregnant or are pregnant or breastfeeding, take a multivitamin containing 150 micrograms of iodine daily. Not all prenatals pack iodine, so read the label carefully to see what yours offers and make a switch if needed.

While iodine intake is important for healthy thyroid function, you should not take iodine supplements to support thyroid health unless indicated by a doctor who is treating your thyroid disease. But, occasionally cooking with iodized table salt, eating the occasional sushi roll, and digging into a yogurt parfait can help keep your thyroid running smoothly.

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