The Best and Worst Foods for Your Thyroid

• A diet rich in whole foods can help supply the nutrients required to keep your thyroid healthy.
• Some of the best foods for your thyroid include Brazil nuts, seaweed and eggs.
• People with thyroid diseases should limit foods like soy, caffeine and raw cruciferous vegetables.

Your thyroid is a small butterfly-shaped gland that lies against your windpipe, just below your voice box. This gland produces hormones that affect nearly every organ in your body, from your heartbeat and body temperature to digestion, metabolism, mood, respiration and more. When your thyroid is working properly, it releases a steady stream of thyroid hormones into your bloodstream, primarily triiodothyronine (T3) and thyroxine (T4). When more is needed—like during pregnancy or when you’re feeling cold—it usually has no problem pumping out more. 

But sometimes, your thyroid can begin to make either too much or too little of these hormones. This can be due to several different types of thyroid diseases. In fact, 20 million people in the United States have some type of thyroid disease, and women are up to eight times more likely to have it than men. Common thyroid diseases include (but aren’t limited to):

• Hypothyroidism: Occurs when your thyroid is underactive and produces too little of the hormones needed to function well. Symptoms include intense fatigue, weight gain, brain fog and depression. Hashimoto’s disease, an autoimmune disorder, is the most common cause of hypothyroidism.
• Hyperthyroidism: If your thyroid gland churns out too much hormone, you have an overactive thyroid. Symptoms include weight loss, anxiety, weakness and sleep disturbance.

Since your thyroid affects your body’s function, it’s important to eat nutritious foods that support thyroid health. We reached out to several registered dietitian nutritionists to learn what foods can improve your thyroid health—and which are best to avoid.

Best Foods for Your Thyroid 

1. Brazil Nuts 

These large, dense tree nuts come from the Amazon rainforest and are packed with nutrition. Selenium is an essential mineral with antioxidant properties that’s vital for thyroid health. “I often recommend eating a single Brazil nut each day, which provides more than the daily recommended amount of selenium,” says Josten Fish, RD. However, it’s important to enjoy Brazil nuts in moderation—consuming at most 3 Brazil nuts per day. Since they’re such a potent source of selenium, consuming too many can lead to nutrient toxicity. 

2. Seaweed 

Seaweed—starring in sushi rolls or purchased in snack sheets called nori—is chock-full of iodine, another essential nutrient that allows the thyroid to do its job. That said, there are certain precautions folks who have thyroid disease may need to take. “While iodine is crucial for thyroid function, too much iodine can harm the thyroid gland, especially in individuals with Hashimoto’s,” says Danielle Smith, RDN. Iodine supplements, as well as eating iodine-rich foods, can pose a health risk for this population, so if you have Hashimoto’s, talk to a healthcare provider before incorporating them into your diet.

3. Eggs 

Eggs are a complete protein and a great source of vitamin B12 and choline. When it comes to thyroid health, they’re the complete package, containing selenium, iodine and tyrosine, an essential amino acid that is a building block of thyroid hormones, says Smith. While eggs are a source of dietary cholesterol, keep in mind that this is a needed nutrient that your body uses to make hormones, and the warnings about dietary cholesterol consumption have been removed from the 2020-2025 Dietary Guidelines for Americans.

4. Beef 

Not only is beef a natural source of protein, heme iron and vitamin B12, it’s also a source of zinc. An essential mineral, zinc helps fight off infection, makes DNA and plays an important role in thyroid health, too. Enjoy beef in moderation to support your thyroid with the nutrients it needs to function at its best. 

5. Leafy Greens 

Leafy greens are rich in two categories of nutrients that assist thyroid function: antioxidants and B vitamins. There are eight different B vitamins, and leafy greens (like spinach) contain nearly all of them. “Antioxidants help protect the thyroid from oxidative stress, and B vitamins play a role in energy metabolism and thyroid function,” says Smith.

Worst Foods for Your Thyroid 

1. Soy 

Soy foods like tofu, edamame and soymilk have many health benefits. However, some data suggests soy foods may interfere with common medications used to treat hypothyroidism. However, when researchers reviewed studies focusing on this topic, they found that while some case reports suggested that soy might interfere with the absorption of certain thyroid health-supporting medication, the most reliable study (a randomized cross-over trial) found no significant differences when soy and this medication were taken together. Overall, if soy does interfere with this medication’s absorption, its impact seems to be minimal. However, it’s always a good idea to talk to a healthcare professional, dietitian or pharmacist if you have any questions about the timing of your thyroid medication and the food you eat.

2. Caffeine 

Coffee and other caffeinated beverages, like energy drinks, tea and soda, might need to be limited or avoided if you’re taking medication for a thyroid condition. “High levels of caffeine can exacerbate some symptoms of hyperthyroidism and cause anxiety and rapid heart rate,” says Fish. Research suggests that drinking a moderate amount of caffeine, like what you’d get from 1 to 3 cups of coffee a day, might increase levels of TSH, a hormone that helps regulate your thyroid. This means moderate caffeine consumption could have some effect on how the thyroid works, though it’s not completely clear how or why this happens.

3. Raw Cruciferous Vegetables 

Veggies in this family—broccoli, cauliflower, Brussels sprouts, kale, bok choy and cabbage—have a long list of health benefits. If you’re taking thyroid medication for Hashimoto’s, you may want to be careful about how they’re prepared. “Raw cruciferous vegetables contain goitrogens that can affect thyroid function and should be limited,” says Fish. “Cooking these vegetables helps to reduce the goitrogenic activity and makes them a better option for those with hypothyroidism,” she explains.

However, more recent data suggests that these foods may be a-ok for this population, so always consult with a healthcare provider. Some studies suggest that eating these vegetables as part of a daily diet is safe and doesn’t harm thyroid function, especially if you’re getting enough iodine in your diet.

4. Foods High in Added Sugar 

There’s an emerging connection between diabetes and thyroid disorders. That’s why it’s important to avoid foods that are more likely to cause blood sugar swings, such as those that are ultra-processed and/or contain a lot of added sugar. “Maintaining steady blood sugar levels is important for managing energy levels and overall health,” says Smith.

5. Trans Fats 

While the Food and Drug Administration has banned trans fats, these partially hydrogenated oils can still be found in trace amounts in foods like microwave popcorn, refrigerated doughs, fried foods, margarine and commercially baked snacks. (Your intake can add up if these foods are often included in your diet.) “Trans fats affect the way the brain and thyroid communicate. That is why many people may suffer from brain fog and other cognitive issues,” says Rosa Becerra-Soberon, RDN. More studies need to be done, but some data suggest that there’s a connection between the inflammation linked to trans fat intake and thyroid health concerns.

Our Expert Take 

The health of your thyroid has ripple effects throughout your whole body. Eating a diet rich in whole foods can help supply you with the nutrients required to keep your thyroid healthy. For personalized recommendations about what to eat or avoid to support your thyroid, speak with a healthcare provider or registered dietitian.