The thyroid gland plays a crucial role in regulating metabolism, growth, and development. It is controlled by the pituitary gland, which produces thyroid stimulating hormone (TSH). TSH signals the thyroid to produce thyroid hormones T3 and T4. These hormones regulate vital body functions like heart rate, body temperature, and metabolism.
When the thyroid becomes overactive (hyperthyroidism) or underactive (hypothyroidism), it can lead to various health problems. Although thyroid disorders are often caused by autoimmune diseases, radiation exposure, medications, or other medical conditions, the foods you eat can also impact thyroid function.
Some nutrients and compounds found naturally in certain foods influence thyroid hormone synthesis and release. Eating too much or too little of these foods may aggravate existing thyroid problems or even trigger new ones in some cases.
This article will explore how certain foods and food compounds can influence thyroid function and possibly trigger hyper or hypothyroidism in susceptible individuals.
Foods that may adversely affect thyroid function
Soybean and soy-based foods
Soybeans and soy products like tofu, edamame, soy milk, and tempeh naturally contain compounds called isoflavones. Isoflavones are a type of plant estrogen that can interfere with the body’s ability to use iodine. Iodine is an essential mineral that the thyroid requires to produce thyroid hormones.
Eating soy foods regularly can potentially lead to hypothyroidism or goiter (enlarged thyroid) in individuals with an underlying iodine deficiency. It may also exacerbate autoimmune thyroid problems like Hashimoto’s disease.
However, moderate soy intake doesn’t seem to affect thyroid function in healthy individuals who aren’t iodine deficient. Restricting soy is generally only recommended for people with compromised thyroid function. Around 30mg of soy isoflavones per day, or 1-2 servings of soy foods, is considered safe for most people.
Gluten-containing foods
People with celiac disease or non-celiac gluten sensitivity are more likely to develop autoimmune thyroid diseases like Hashimoto’s and Graves’ disease.
Eating gluten triggers inflammation and autoantibody production, which can spur the immune system to attack the thyroid gland. Going gluten-free can help manage these autoimmune conditions.
Even in people who don’t have gluten intolerance, excess refined gluten from processed foods may promote inflammation and thyroid dysfunction. Sticking to whole food sources of gluten like oats, barley, and sprouted whole wheat may be better for thyroid health.
Cruciferous vegetables
Cruciferous vegetables like broccoli, cauliflower, cabbage, kale, turnips, Brussels sprouts, and bok choy are very nutrient-dense. But they also naturally contain small amounts of compounds called glucosinolates, which may suppress thyroid function.
These compounds can block iodine absorption and interfere with thyroid hormone synthesis in those predisposed to thyroid dysfunction.
However, thyroid problems from cruciferous vegetables only tend to occur with very high intakes of over 5 servings per day. Moderate cruciferous vegetable intake as part of a healthy diet does not negatively impact thyroid function in most people. Light cooking may also help reduce the goitrogenic effects.
Fatty foods
Diets high in saturated fat and cholesterol can lead to hypothyroidism over time. Saturated fats may reduce absorption of iodine, while high cholesterol can lower thyroid hormone levels.
Polyunsaturated omega-6 fats found in vegetable oils may also contribute to inflammation and potentially disrupt thyroid function when consumed in excess.
Replacing trans fats and saturated fats with anti-inflammatory monounsaturated fats from olive oil, avocados, nuts, and fatty fish may help prevent thyroid problems.
Refined carbohydrates
Eating lots of refined grains, added sugars, and starchy foods like white bread, pasta, sodas, and desserts promotes inflammation and insulin resistance. High blood sugar and insulin elevate TRH, which increases TSH. This can lead to thyroid overactivity in susceptible individuals.
Choosing whole, unprocessed carbohydrate sources like whole grains, starchy vegetables, legumes, and fruits may prevent blood sugar spikes that tax the thyroid.
Alcohol
Drinking excessive amounts of alcohol can reduce blood levels of thyroid hormones T3 and T4. It may also contribute to iodine deficiency and autoimmune thyroiditis.
Moderate alcohol intake hasn’t been shown to affect thyroid function in healthy people. But those with hypothyroidism should minimize alcohol consumption, as it may exacerbate hormone deficiencies.
Coffee and tea
Caffeinated beverages like coffee, black tea, and energy drinks can block thyroid hormone absorption and elevate cortisol levels. Over time, excessive caffeine intake may worsen hormonal imbalance.
Limiting caffeinated beverage consumption to 1-2 cups per day should not affect thyroid function in most healthy people. But those with autoimmune thyroid disorders may want to moderate intake further.
Foods and nutrients that support thyroid function
While some foods may hinder thyroid function, others actually help optimize hormone levels. Incorporating more of these foods into your diet can benefit thyroid health.
Iodine-rich foods
Iodine is the main component of thyroid hormones T3 and T4. Deficiency can lead to hypothyroidism and goiters.
Good food sources include seaweed, seafood, eggs, dairy products, prunes, lima beans, and iodized salt. Just 1/4 teaspoon of iodized salt provides a significant portion of the recommended daily iodine intake.
Selenium-rich foods
Selenium helps convert T4 into active T3 thyroid hormone. It also reduces thyroid antibody levels in Hashimoto’s disease.
Brazil nuts, oysters, organ meats, tuna, sardines, eggs, brown rice, sunflower seeds, mushrooms, and spinach are high in selenium. Just 2 Brazil nuts provide enough selenium for daily needs.
Zinc-rich foods
Zinc enables proper TSH signaling to the thyroid gland. Deficiency may contribute to hypothyroidism.
Good sources include oysters, red meat, poultry, seafood, nuts, seeds, legumes, yogurt, and whole grains.
Vitamin D-rich foods
Vitamin D signals receptor cells that produce thyroid hormones and regulate autoimmune responses. Low levels are linked to increased risk of Hashimoto’s disease and Graves’ disease.
Fatty fish, egg yolks, liver, vitamin D-fortified foods, and 15 minutes of daily sun exposure can maintain optimal vitamin D status. Supplements may be appropriate for those with deficiency.
Tyrosine-rich foods
Tyrosine is required for production of thyroid hormones T3 and T4. L-tyrosine supplements and tyrosine-rich foods may help address hormone deficits in hypothyroidism.
Pumpkin seeds, almonds, avocados, lima beans, cheese, soy products, meat, fish, eggs, spirulina, and bananas supply tyrosine.
Anti-inflammatory foods
Chronic inflammation appears to suppress thyroid function. An anti-inflammatory diet centered around vegetables, fruits, omega-3 fats, nuts, olive oil, and antioxidant spices like turmeric helps reduce inflammation and support thyroid health.
Probiotic foods
Probiotic foods like yogurt, kefir, sauerkraut, kimchi, and other fermented foods replenish beneficial gut bacteria. They help reduce inflammation and autoimmune reactions that may otherwise trigger thyroid problems.
Balanced meals with protein, fat, and fiber
Eating balanced meals with protein, healthy fats, and fiber stabilizes blood sugar, insulin, and appetite-regulating hormones. This provides a favorable metabolic environment for proper thyroid function.
Foods to eat and avoid for optimal thyroid health
Here is a concise list summarizing optimal food choices for thyroid health:
Foods to eat:
– Iodine: Seafood, eggs, dairy, iodized salt
– Selenium: Brazil nuts, seafood, meats, eggs
– Zinc: Oysters, meat, seafood, nuts, seeds
– Vitamin D: Fatty fish, egg yolks, fortified foods
– Tyrosine: Nuts, avocados, cheese, soy, meat, fish, eggs
– Anti-inflammatory foods: Fruits, vegetables, omega-3 fats
– Probiotics: Yogurt, kefir, fermented foods
– Balanced meals with protein, healthy fats and fiber
Foods to avoid or limit:
– Soy: Moderate soy intake under 30mg isoflavones daily
– Gluten: Avoid with thyroid autoimmunity or sensitivity
– Cruciferous vegetables: Limit to 1-2 servings daily when cooked
– Saturated fats: Limit intake from fatty meats, butter, cheese
– Refined carbs: Reduce processed grains, sugars, starch
– Caffeine: Limit to 1-2 cups coffee or tea per day
– Alcohol: Avoid excess intake, especially with hypothyroidism
Tips for improving thyroid health through diet
Here are some tips to support your thyroid through dietary and lifestyle habits:
– Ensure adequate iodine intake by using iodized salt and eating seafood 1-2 times per week. Too much or too little iodine can affect thyroid function.
– Incorporate selenium-rich Brazil nuts as a snack a few times a week. Just 1-2 nuts daily provides enough.
– Choose polyunsaturated and monounsaturated fats like olive oil over saturated animal fats.
– Reduce excess refined carbs and added sugars that may spike blood glucose.
– Stay well hydrated and minimize caffeinated beverages like coffee, tea, and energy drinks.
– Avoid gluten, soy, and cruciferous vegetables if you have autoimmune thyroid disease or are sensitive.
– Supplement with antioxidants like vitamin C, vitamin E, zinc, and selenium to reduce inflammation.
– Treat any vitamin D deficiency to bring levels up to the optimal range of 60-80 ng/mL.
– Discuss tyrosine or iodine supplements with your doctor if deficient.
– Eat more anti-inflammatory probiotic foods to improve gut health and immunity.
– Manage stress through relaxing activities to lower cortisol and support thyroid function.
Conclusion
The foods you eat can have significant effects on thyroid health, especially if you have an underlying thyroid disorder. While no specific food will cure hypothyroidism or hyperthyroidism, choosing the right nutrients and avoiding potential triggers can help keep your thyroid functioning at its best.
Work with your healthcare provider to identify any nutritional deficiencies, food sensitivities, or supplement needs. An overall balanced diet low in processed foods and rich in whole foods containing iodine, selenium, zinc, vitamin D, tyrosine, and probiotics will provide optimal nutritional support for your thyroid.
