The Best and Worst Foods for Your Thyroid, According to Dietitians

This little gland has a big job in your body—here’s how to get the nutrients you need to support its function.

Reviewed by Dietitian Emily Lachtrupp, M.S., RD

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, according to the National Library of Medicine.

When your thyroid is working properly, it releases a steady stream of thyroid hormones into your bloodstream, primarily triiodothyronine (T3) and thyroxine (T4), according to the Endocrine Society. 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. According to the American Thyroid Association, 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) the following:

• 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.

Related: The Best Diet for Hashimoto's Disease

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, according to the National Institutes of 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, owner of Dietitian Meets Mom.

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, a registered dietitian with Top Nutrition Coaching. Iodine supplements, as well as eating iodine-rich foods, can be a risk, says the National Institute of Diabetes and Digestive and Kidney Disease, so if you have Hashimoto’s, talk to your doctor before incorporating them into your diet.

3. Eggs

Eggs are a complete protein and a great source of vitamin B12 and choline. And when it comes to thyroid health, they’re the complete package, packing 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 have been removed from the Dietary Guidelines for Americans.

4. Beef

Not only is beef a fabulous source of protein, heme iron and vitamin B12, it’s also a great way to get a dose of zinc. An essential mineral, zinc helps fight off infection, makes DNA and plays an important role in thyroid health, too, according to 2023 research in Frontiers in Endocrinology.

5. Leafy Greens

Leafy greens are rich in two 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, soy foods may interfere with thyroid medications used to treat hypothyroidism, according to the Mayo Clinic. That’s why it’s recommended to consume soy at least an hour after taking your medication, which gives your body ample time to fully absorb the drug. Of course, talk to your doctor 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. If you take thyroid medication, wait 30 to 60 minutes before drinking coffee, suggests UCLA Health.

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.

4. Foods Rich in Added Sugar

There’s an emerging connection between diabetes and thyroid disorders, an overview published in Diabetes & Metabolism Journal in 2022 says. 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 dangerous 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 women may suffer from brain fog and other cognitive issues,” says Smith. More studies need to be done, but researchers in Frontiers in Endocrinology in 2022 suggest that there’s a connection between the inflammation caused by trans fats and thyroid problems.

The Bottom Line

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 your health care provider.

EatingWell.com, February 2024

Read the original article on Eating Well.