If your metabolism is sluggish or you are overly tired or feel cold all the time, you may not be getting enough iodine in your diet. If you're eating plant-based you’ve likely heard about the importance of getting B12, iron, and vitamin D but what about iodine? Iodine is a vital nutrient for thyroid health that has a major impact on your body's metabolism, energy levels, and temperature regulation. Iodine deficiency can lead to thyroid disorders including hypothyroidism, where your thyroid doesn't produce enough hormone, so it’s essential to eat foods that are rich in iodine. Fortunately, it is easy to do once you know what to look for.

Why iodine is crucial to thyroid health

“Your thyroid gland needs iodine to make hormones that are crucial for regulating your body's different functions,” says Dr. Amelia Brown, MD, of Oregon Health and Science University Hospital in Portland, OR. Thyroid hormones are found throughout the bloodstream, so imbalances in them affect the entire body. Thyroid health is critical for many vital functions.

Dr. Elliana Rose, MD, elaborates “Iodine is required for the thyroid gland to produce two specific thyroid hormones, T3 and T4 (triiodothyronine and thyroxine). They control every cell and organ in our bodies, she explains. "They play the role of regulating metabolism.” A recent study compared the nutritional status between ‘health conscious’ vegans and non-vegans. Iodine was the only nutrient in which vegans didn’t outperform non-vegans. It’s clear plant-based eaters should focus more on getting their daily dose of iodine.

What is iodine?

Iodine is a trace mineral found in saltwater and soil in varying amounts. The most common dietary sources include iodized salt, fish, and dairy. The iodine in dairy comes from supplementation of cattle feed and the disinfectants used in milking. Not exactly whole food sources. Fish are high in iodine because they eat plenty of macroalgae which is high in iodine (and also where much of the iodine in supplements comes from).

Should you supplement iodine? Dr. Andrea Paul, MD, Co-Founder of Health Media Experts and Medical Advisor at Illuminate Labs, says, “An average healthy person has no need for supplemental iodine. Iodized salt is the most cost-effective way to increase iodine intake, but there are also food sources like seaweed that are rich in the mineral.” Iodized salt will prevent deficiency, but anyone with high blood pressure needs to be aware of the health risks associated with high sodium intakes, such as hypertension and increased risk of stroke.

Too much iodine can lead to iodine toxicity. According to Marie Salbuvik, RD, cautions, “It's important not to exceed the Recommended Daily Allowance (RDA) of iodine as you could experience adverse health effects such as changes in how your thyroid gland works.”

Adequate daily intake for adults is 150 micrograms. Pregnant women need 220 micrograms, breastfeeding women require 290 micrograms, and children under 13 need 120 micrograms.  “The reason it varies from person to person is our needs are dependent on different factors such as age, menstruation status, pregnancy status, and current supplementation,” explains Jamie Hickey, Registered Dietician and founder of Truism Fitness.

How iodine impacts thyroid health

The thyroid is a small, butterfly-shaped gland located in the middle of your neck above the collar bone that regulates your metabolism by producing hormones that control how cells use energy. Your metabolism regulates many important functions, but most people know of it because of its impact on metabolism.

Hormone imbalances can lead to hypothyroidism and hyperthyroidism. Hypothyroidism is a decrease in thyroid hormone production. Hyperthyroidism is an increase in thyroid hormone production. Certain nutrients significantly impact thyroid health, like iodine, selenium, and zinc. If you’re unsure how to include these in your diet, add the following foods that support thyroid health to your diet.

Jamie Hickey, RD, explains, “Without enough iodine, the production of important hormones can be disrupted and lead to an underactive or overactive thyroid.” Without iodine, your key thyroid becomes inflamed and metabolic processes slow down. Conversely, too much iodine can cause hormone overproduction.

How to know if you are deficient in iodine

Your body will eventually present symptoms of hypothyroidism if you’re not getting enough iodine. The most common are slowed metabolism, fatigue, cold sensitivity, weight gain, and goiters (thyroid gland enlargement). Too much iodine may cause hyperthyroidism. Symptoms include high metabolic rate, rapid heartbeat, increased blood pressure, weight loss, and mood swings. “You know you’re deficient in iodine by assessing how you feel,” Dr. Lizz Kinyua, MD,- Founder and Director of Mentor Medics, tells The Beet.

Here’s a list of seven iodine-rich foods to optimize thyroid health. It’s important to note the amount of iodine present in foods is highly variable depending on the soil’s iodine content.

7 plant-based foods rich in iodine

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Seaweed

Dried seaweed or sea vegetables like nori, dulse, kombu, and kelp top the list as your best plant-based sources of iodine. Be sure to eat a variety of them as they contain varying amounts of iodine. Kelp is particularly rich containing up to 2,000 micrograms per tablespoon. Snack on sheets of nori, sprinkle dulse flakes on a salad, or add kombu to soup.

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Cranberries

Cranberries may not top your favorite food list, but one ounce of the tiny red power food contains 100 micrograms of iodine. That’s 67 percent of your daily value! They also contain antioxidants and lower blood pressure. They're a nice addition to desserts and salads, like this delicious Walnut and Cranberry Salad

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Potatoes

One medium-sized baked potato packs 40 percent of your RDA with 60 micrograms of iodine. There’s no shortage of ways to enjoy potatoes. Make homemade french fries, bake them, mash them - just be sure to leave the skin on as that’s where the majority of iodine and other nutrients are stored.

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Prunes

Prunes are the highest dried fruit source of iodine. Five dried prunes provide 13 micrograms of iodine (9 percent of your RDA). They're also an excellent source of fiber, potassium, and iron. Eat them on their own or add to trail mixes. Pro Tip: Store prunes in the freezer to make them a delicious frozen treat.

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Strawberries

Who doesn’t love strawberries? Besides being nature’s candy, strawberries contain vitamin C, potassium and 13 micrograms of iodine per cup. Be sure to buy organic as their porous skin absorbs more pesticides than other fruits. If you’re not a fan of strawberries try buying them frozen and adding to smoothies.

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Lima Beans

One cup of cooked lima beans provides 10 percent of your daily value with 16 micrograms of iodine. Lima beans are high in fiber, magnesium, and plant protein. They’re a great addition to any salad or bowl. Try making roasted lima beans for a healthy crunchy snack.

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Iodized Salt

Iodized salt is last on the list but it’s the most common source of iodine. Only a quarter teaspoon (1.5 grams) is required to reach your daily value. The drawbacks are the negative health outcomes associated with high sodium intake and the risk of getting too much iodine.

The Food and Drug Administration (FDA) and American Heart Association (AHA) recommend a maximum sodium intake of 2,300 milligrams per day (approximately 1 teaspoon of salt). The AHA advises to not exceed 1,500 milligrams a day for heart health, especially if you have high blood pressure. Reducing sodium intake by 1,000 milligrams a day can significantly lower blood pressure. The amount of sodium in salt varies depending on the type of salt, but typically a quarter teaspoon contains 550-600 milligrams of sodium. With that said, using iodized salt in moderation won’t hurt and can be a reliable way to meet your iodine needs.

Bottom line: Iodine is critical for thyroid health and is required in a healthy diet.

It's possible to get enough iodine on a plant-based diet, and not load up on the salt. Consult your doctor or nutritionist to determine if you’re deficient in iodine and if supplementation is required.