Iodine is not that common in many foods, but it’s a thyroid -regulating powerhouse. “The primary responsibility of iodine is supporting healthy metabolism, and lowering inflammation to prevent chronic disease,” says Samantha Franceschini , a health coach at Parsley Health New York. If you have a diagnosed thyroid issue and to prevent future issues, ensure you’re getting iodine into your day and focus on other thyroid health-boosting nutritional choices to round out your diet further.
The thyroid gland is often referred to as the “master gland,” Franceschini explains, and its main hormone, TSH, or thyroid-stimulating hormone, helps the gland produce its other hormones, T3 and T4. “These hormones regulate body temperature, digestion, energy levels, mood, weight, and brain function, and micronutrients are needed for these conversions to happen, the number one being iodine,” Franceschini says. If the iodine levels in your body are too high, or, more commonly, if your body is deficient in iodine, you may start to notice changes in your energy, metabolism, and mood, which may be signs of a larger thyroid condition.
If you’re feeling fatigued and are experiencing symptoms like hair loss or unusual changes in your weight, your thyroid may be compromised. Lab work can evaluate your levels of key thyroid hormones. If the thyroid is not functioning at its normal rate and producing optimal amounts of the necessary thyroid hormones, you may develop a thyroid condition, like hypothyroidism, hyperthyroidism, goiters, or even thyroid cancer.
Treating thyroid conditions with diet and lifestyle changes and possibly supplements or medication is important because other conditions can develop if thyroid dysfunction is not properly treated, like liver, muscle, heart, and metabolic conditions. “When you have a thyroid issue, it affects the body’s functions as a whole, which includes functions of the liver, kidney, brain, muscles. It can contribute to high blood pressure, brain fog , and cardiovascular disease, too,” Franceschini says. These are just a few of the most common thyroid health conditions.
Iodine deficiency most commonly causes low function of the thyroid, or hypothyroidism. The most common symptoms of hypothyroidism are unexplained weight gain, fatigue , and hair loss.
Recent research has proven that if you have too much iodine in your system, it might cause hyperthyroidism, the over-functioning of the thyroid and consequently overly rapid metabolism. Symptoms can include racing heart and weight loss.
In some cases, the immune system attacks the thyroid, leading to autoimmune conditions such as Hashimoto’s disease or Grave’s disease. These conditions are likely to cause hypothyroidism or hyperthyroidism, respectively. The symptoms of Hashimoto’s or Grave’s may be similar to other thyroid conditions (fatigue and weight changes) but also may present with other symptoms.
“Goiter means simply that there is an abnormal enlargement of the thyroid gland,” Franceschini says. Being iodine-deficient may cause goiters–the thyroid is enlarged and likely working too slowly, which can then absorb too much iodine, she adds. This may be the right place for iodine supplementation, but make sure you consult your doctor or health coach first to get the right dosage for your iodine levels.
While it’s tricky to find foods with iodine, it’s not impossible. Try these iodine-rich foods for a thyroid boost if you’re deficient. If you eat a vegetarian or vegan diet without seafood, Franceschini recommends asking your doctor or health coach about the right dose for iodine supplements.
Iodine is most bioavailable, and highest in daily value in seaweeds like kelp, nori, kombu, and wakame. Luckily it’s common not just in Asian cuisine, but as a popular snack in its crunchy, dried form. Plus, it’s a vegan source of iodine.
2. Wild Fish
You can also find iodine in large doses in shellfish and wild fish. Specifically, sardines, salmon, and shrimp are especially high in iodine.
Salt in the past was often iodized, which was a major source of iodine for some people. Now, you can actually absorb more iodine in sea salt that is infused with seaweed flakes, Franceschini recommends–you can use the umami flavor to season your food.
Iodine is also available in small doses in certain legumes like navy beans, lima beans, kidney beans, and peas. These are a decent option if you don’t eat seafood or animal protein , but they only contain minimal amounts of iodine. For example, the average adult needs about 150 mcg of iodine per day, according to the National Institute of Health , and lima beans contain around 8 mcg , so it’s best to seek out the seaweed or seaweed salt if you can in addition to these sources.
Iodine is majorly necessary, but there are other micronutrients that also help the thyroid function properly. These micronutrients work together with iodine to help balance levels of thyroid hormones, help the body successfully process those thyroid hormones, and help the brain send out the right signals to produce the necessary thyroid hormones in the first place.
1. Selenium is almost equally important to the thyroid as iodine, as it helps balance levels of T4 hormones. The best source of selenium is Brazil nuts, Franceschini says—you can get all the selenium you need from just a couple of nuts per day. If you don’t eat Brazil nuts, you can also get your fill from spinach, turkey, grass-fed beef, and seafood like yellowfin tuna, halibut, and sardines.
2. Zinc is needed alongside selenium to convert the thyroid hormone T4 to T3, the active form of the hormone, in order for the body to use it successfully. It also helps balance T4 and T3 hormone levels. Mainly, it’s important to consume a well-balanced diet of anti-inflammatory foods, Franceschini says. You can find zinc in a number of plant-based foods, such as pumpkin seeds, chickpeas, lentils, and cashews.
3. B vitamins, especially vitamin B12, are necessary for thyroid health and regulating thyroid hormones. Because B12 is found in high concentrations in meat, fish, eggs, and dairy , you may be deficient if your diet is vegetarian, vegan, or simply low in animal products. In that case, spirulina supplements are a great substitute source of B vitamins, says Franceschini.
4. Vitamin D is essential for brain activity, as the brain and your thyroid connect through the pituitary gland, which helps regulate all thyroid hormones. It may be worth taking a Vitamin D supplement if you don’t eat seafood or dairy—fatty fish like salmon and tuna and milk products are key sources of the vitamin.
5. Iron is similar to B vitamins, in the regulation of the “mass equations” in the body of the thyroid hormones, Franceschini explains. Studies have found that iron deficiency can be linked to hypothyroidism. Iron is found in animal protein sources like grass-fed beef, but also found in high concentrations in green, leafy vegetables—spinach is a great source.
6. Tyrosine, an amino acid, works together with iodine to produce thyroid hormones. Foods that are high in tyrosine include mostly animal products, such as beef, pork, lamb, fish, eggs, and dairy, but it can also be found in nuts, seeds, and whole grains as vegan sources of the amino acid.
Mara is a freelance journalist whose print and digital work has appeared in Shape, Brit+Co, Marie Claire, Prevention, and other wellness outlets.
Most recently, she was a member of the founding team of Bumble Mag, a branded content project for Bumble at Hearst Corporation. She enjoys covering everything from women's health topics and politics to travel. She has a degree in Communications as well as Italian Studies from Fordham University.