Hypothyroidism Diet: How Nutrition Affects the Thyroid, and Foods to Avoid

If you have hypothyroidism (an underactive thyroid), you know that key ways to feel your best include taking thyroid medication (like levothyroxine) and having regular lab work. Thyroid hormones play a key role in metabolism, the body’s process of turning food into energy. These hormones support the health of your heart, brain, muscles, and lungs. They also support your growth. 

But does what you eat also affect your thyroid hormone levels? In addition to taking medication, paying attention to your diet can help you feel better, improve your long-term health, and may even improve your thyroid function. Here’s how. 

What vitamins and minerals can affect the thyroid?

You may wonder about the role of specific nutrients, like vitamins and minerals. Let’s dive into what the science shows and what experts say about the role of nutrition in hypothyroidism.

Iodine

Iodine helps regulate how much thyroid hormone the body makes. Iodine deficiency is one of the most common and preventable causes of hypothyroidism throughout the world. But, thanks to a good amount of iodine in our salt, it’s rare in the U.S. 

Keep in mind that unnecessary supplementation or too much iodine can also lead to thyroid problems. That said, pregnant women everywhere should take iodine to make sure they get enough thyroid hormone to help the baby’s brain development. The American Thyroid Association recommends that all U.S. women who are planning for pregnancy, pregnant, or breastfeeding should supplement with 150 mcg of iodine daily.

Selenium

Selenium plays an essential role in making thyroid hormone. Selenium deficiency can lead to low thyroid levels, and it’s linked to a type of hypothyroidism called autoimmune thyroiditis (also called autoimmune hypothyroidism or Hashimoto’s disease). Taking selenium supplements can be helpful if you’re deficient. But, like iodine deficiency, selenium deficiency is rare in the U.S.

Some research shows that when people with autoimmune thyroiditis take selenium supplements, it can lower the level of some blood markers of the condition. But there’s no evidence that it changes how mild or severe the condition is, how much medicine you need, or how you feel overall. So, experts don’t recommend selenium supplementation to prevent or treat hypothyroidism. 

Zinc

Some evidence links low zinc levels to low thyroid hormone levels. But the science isn’t strong enough to recommend routine zinc supplements for people with hypothyroidism. And most Americans get enough zinc through a regular diet.

Iron

The relationship between iron and the thyroid is complex. Iron deficiency makes it harder for the thyroid gland to make thyroid hormone. And low thyroid levels can lead to low iron levels by reducing iron absorption in the gut. To muddy the waters even more, some of the symptoms of low iron and hypothyroidism are the same, including hair loss, feeling cold, and fatigue. 

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For people with hypothyroidism and low iron, taking iron supplements can help thyroid function. But iron supplements can make it harder for the body to absorb thyroid medication. So, iron supplements and thyroid medication shouldn’t be taken at the same time. 

Vitamin D

There’s evidence that vitamin D deficiency may be linked to autoimmune hypothyroidism, but one doesn’t cause the other. The evidence isn’t clear enough to recommend vitamin D treatment for people with an underactive thyroid. 

What foods should you eat or avoid with hypothyroidism?

If you eat a well-balanced diet, you’re unlikely to have nutrient deficiencies, like those mentioned above. For someone without nutritional deficiencies, there isn’t good evidence that eating or avoiding certain foods will help your thyroid function.

But some foods can still play a role in supporting thyroid health. We’ll review what the science says about foods good for low thyroid, and potential foods to avoid with hypothyroidism.

Foods to prioritize

The best foods to eat if you have hypothyroidism are those that give you a variety of nutrients and vitamins. Dr. Sonal Chaudhry, assistant professor of endocrinology, recommends aiming for a well-balanced diet that lowers inflammation and supports general health. This can help prevent heart and metabolic complications of hypothyroidism down the line. This means prioritizing:

• Plenty fruits and vegetables (especially leafy green vegetables)

• Legumes and nuts 

• Whole grains

• Dairy foods

• Eggs

• Lean protein (especially fish and seafood)

• Healthy fats (from olive oil and fatty fish)

Foods to limit

Wondering about which foods to avoid with hypothyroidism? “You don’t need to avoid specific foods just because you have hypothyroidism,” Chaudhry says. But the foods you eat can potentially impact your thyroid hormone levels. Here’s what you need to know.

It’s important to limit foods that are more likely to lead to chronic conditions, like diabetes and heart disease.

Foods to limit include: 

• Red meat

• Processed meats

• Ultra-processed foods

• Added sugars

• Sodium

• Alcohol

• Unhealthy fats (saturated and trans fats)

Can goitrogens affect your thyroid?

Goitrogens are substances that make it harder for your body to produce thyroid hormone. Eating very large amounts of these foods in raw form can make it harder for your thyroid gland to work. They’re called goitrogens because this could lead to a goiter (an enlarged thyroid).

Food goitrogens include:

• Cassava

• Lima beans

• Linseed

• Sorghum

• Sweet potatoes

• Cruciferous vegetables (like cabbage, kale, cauliflower, broccoli, and turnips)

• Flavonoids (like soy or millet)

But goitrogens are central to a healthy diet. And you can eat several servings a day without them having any effect on your thyroid health. Also, cooking these foods makes them even less likely to have an effect on your thyroid gland. 

So, don’t cut back on these essential foods. The only exception is if you have an iodine deficiency. If you have low iodine, goitrogens are more likely to interfere with thyroid function. So, you should minimize the above foods until your iodine level is normal. But, remember, iodine deficiency is highly unlikely in the U.S.

Does a gluten-free diet improve thyroid health?

Many people with hypothyroidism also have celiac disease. That’s because both autoimmune hypothyroidism and celiac disease are autoimmune conditions. So, having celiac disease increases the risk of hypothyroidism by up to four times. 

But does following a gluten-free diet help if you have an underactive thyroid? In short, no. Although some research suggests that a gluten-free diet might have a small effect on thyroid function, there isn’t evidence that a gluten-free diet improves outcomes in people with an underactive thyroid. 

Is being vegan bad for your thyroid?

No, being vegan isn’t necessarily bad for your thyroid. “But, if you’re vegan,” Chaudhry says, “you should make sure that you have enough iodine in your diet to support thyroid function, since seafood and dairy products contain iodine.” Consuming iodized salt is an easy way to make sure you have sufficient iodine levels, if you’re not eating seafood and dairy products in your diet.

Another thing to consider is that vegan diets are often rich in soy products. Chaudhry cautions against consuming excessive amounts of soy products. These can interfere with how your body absorbs thyroid medication (more on this below). 

Can foods affect how you absorb hypothyroidism medication?

Some foods and nutrients interfere with how much thyroid hormone medication your body absorbs. This can make medication less effective. Your body may have a harder time absorbing thyroid medicine if you take it around the same time as: 

• Coffee

• Dairy products

• Calcium-containing supplements

• Iron

• Fiber

• Soy 

• Aluminum supplements

• Chromium supplements

Here’s a good general rule: Take thyroid medication on an empty stomach (about 30 to 60 minutes before meals) and about 4 hours apart from vitamins or supplements that contain iron, aluminum, calcium, or chromium. Otherwise, your body might not absorb enough of the thyroid medication.

Some data shows that vitamin C might help your body absorb levothyroxine. Talk to a healthcare professional about possibly taking your levothyroxine with vitamin C. 

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Written by:

Melody B. Jones, NP

Melody Jones, NP, has over a decade of experience as a nurse practitioner. She works in a multi-specialty practice in Atlanta, Georgia, and is a part of the American Academy of Nurse Practitioners.

Edited by:

Katie E. Golden, MD

Katie E. Golden, MD, is a board-certified emergency medicine physician and a medical editor at GoodRx.

Reviewed by:

Karen Hovav, MD, FAAP

Karen Hovav, MD, FAAP, has more than 15 years of experience as an attending pediatrician in a variety of clinical settings. She has worked in a large academic center in an urban city, a small community hospital, a private practice, and an urgent care clinic.

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