What is the best diet for underactive thyroid?

October 20, 2025 •

4 min read

According to the British Thyroid Foundation, there is no single "miracle" diet for thyroid disorders, but a healthy, balanced eating pattern is crucial for managing symptoms. Understanding what is the best diet for underactive thyroid can complement your medical treatment and support overall wellness.

Quick Summary

Focus on a nutrient-dense diet with a balance of essential minerals, moderate intake of goitrogenic foods, and proper medication timing to support thyroid function and overall well-being.

Key Points

Nutrient-Rich Diet: Focus on whole, unprocessed foods rich in selenium (Brazil nuts, seafood), zinc (oysters, beef), and iron (lentils, spinach) to support hormone production.
Balance Iodine Intake: Ensure a balanced intake of iodine from sources like iodized salt and dairy, as both deficiency and excess can be problematic, especially with autoimmune conditions.
Moderate Goitrogenic Foods: Consume cruciferous vegetables like broccoli and kale in cooked, moderate amounts to minimize any potential interference with iodine uptake.
Time Your Medication: Take thyroid medication (e.g., levothyroxine) on an empty stomach and several hours apart from high-fiber foods, coffee, soy, and supplements containing calcium or iron.
Consider Anti-inflammatory Diets: Eating patterns like the Mediterranean diet, rich in fruits, vegetables, and lean protein, can reduce inflammation and benefit overall health for those with hypothyroidism.
Avoid Processed Foods and Sugar: Limit intake of processed foods and added sugars, which can contribute to inflammation and weight gain, common concerns with an underactive thyroid.

The Role of Diet in Managing Hypothyroidism

Hypothyroidism occurs when the thyroid gland doesn't produce enough hormones, leading to a slower metabolism and various symptoms like fatigue and weight gain. While medication is the primary treatment, nutrition plays a significant supporting role by providing the necessary building blocks for hormone production and managing inflammation. The goal is not to find a single "cure-all" food, but rather to adopt a balanced eating pattern that supports your body's needs.

Essential Nutrients for Thyroid Health

Selenium

Selenium is a vital trace mineral that helps activate thyroid hormones and protects the thyroid gland from oxidative stress. A balanced diet should provide sufficient amounts, but supplementation may be considered under medical supervision.

Brazil nuts: One of the richest sources; just a few can meet your daily needs.
Seafood: Tuna, sardines, and shrimp are excellent sources.
Eggs: A convenient source of selenium.
Legumes: Beans and lentils provide this mineral.

Iodine

Iodine is a key component of thyroid hormones. While deficiency is a common cause of hypothyroidism globally, excessive intake can be harmful, especially for those with autoimmune thyroid conditions like Hashimoto's. It's crucial to maintain a balanced intake.

Iodized salt: A common and reliable source of iodine.
Seafood: Cod, oysters, and seaweed (in moderation).
Dairy products: Milk, yogurt, and cheese.

Zinc, Iron, and B Vitamins

Several other micronutrients are essential for optimal thyroid function:

Zinc: Supports hormone production and helps regulate TSH levels. Found in beef, oysters, pumpkin seeds, and lentils.
Iron: Deficiency is common in people with hypothyroidism and can impair thyroid function. Sources include lean red meat, poultry, fish, beans, and spinach.
Vitamin B12: Deficiency is often seen in hypothyroid patients. Found in meat, dairy, eggs, and fortified cereals.
Vitamin D: Low levels are linked to autoimmune thyroid conditions. Oily fish and fortified dairy are good sources.

Foods to Embrace and Foods to Limit

For a thyroid-friendly diet, focus on whole, unprocessed foods and be mindful of certain categories that can interfere with thyroid function or medication absorption.

Foods to Embrace

Whole Grains: Brown rice, quinoa, and oats provide fiber for digestion and sustained energy.
Lean Proteins: Chicken, fish, eggs, and legumes support metabolism and overall health.
Fruits and Vegetables: Berries, leafy greens, and other produce are rich in antioxidants and vitamins.
Healthy Fats: Olive oil, avocado, and nuts contain anti-inflammatory properties.

Foods to Limit or Avoid

Goitrogenic Foods: Raw cruciferous vegetables like broccoli, cabbage, and kale contain goitrogens, which can interfere with iodine uptake. Cooking them reduces this effect, and moderate amounts are generally fine.
Soy Products: Soy may interfere with the absorption of thyroid medication, so it's best to time its consumption several hours away from your medicine.
Processed Foods: High in sugar, sodium, and unhealthy fats, these can worsen inflammation and lead to weight gain.
Excessive Fiber: Very high fiber intake can interfere with medication absorption. Discuss with a doctor if your diet is very high in fiber.
Coffee and Caffeine: Can block medication absorption, so it should be taken at a different time.

Medication Timing and Diet

It is critical to separate your thyroid medication (levothyroxine) from certain foods and supplements to ensure optimal absorption.

Take on an empty stomach: Take your medication with only water, typically 30-60 minutes before breakfast.
Avoid calcium and iron: Wait at least four hours after taking your medication before consuming calcium or iron supplements, or foods rich in these minerals.
Mind the fiber: High-fiber meals can interfere with absorption; consult your doctor if you change to a very high-fiber diet.

Comparison of Thyroid-Friendly Eating Patterns


Eating Pattern	Focus & Key Principles	Potential Benefits	Considerations
Mediterranean Diet	Emphasizes fruits, vegetables, whole grains, lean protein (fish), and healthy fats.	Anti-inflammatory properties, protects against cellular damage.	Generally aligns well with thyroid-supporting nutrients; flexible and sustainable.
Anti-Inflammatory Diet	Reduces inflammatory foods (processed items, sugar) and increases anti-inflammatory foods (omega-3s, antioxidants).	Decreases systemic inflammation, which is beneficial for Hashimoto's.	May require more restrictive food choices, especially concerning processed and sugary foods.
Gluten-Free Diet	Eliminates gluten (wheat, barley, rye).	May benefit those with Hashimoto's and coexisting Celiac disease or gluten sensitivity.	Unnecessary for all hypothyroidism patients; requires careful planning to ensure adequate nutrients.

Conclusion

While no single food can cure an underactive thyroid, adopting a balanced, nutrient-rich diet is a powerful tool for managing symptoms and supporting overall health alongside medical treatment. By focusing on essential minerals like selenium, zinc, and a balanced intake of iodine, while being mindful of foods that can interfere with medication, you can positively influence your well-being. Always consult with a healthcare provider or a registered dietitian before making significant dietary changes, especially concerning supplements. For more detailed information on thyroid disorders, consult reliable sources like the National Institutes of Health.

A Sample Daily Meal Plan

Here is an example of a day's meals that incorporate thyroid-friendly foods:

Breakfast: Egg and spinach omelet, served with half an avocado and a handful of berries.
Lunch: Large salad with grilled salmon, chickpeas, and pumpkin seeds.
Snack: A few Brazil nuts and an orange.
Dinner: Stir-fried shrimp and vegetables served with brown rice.

Key Lifestyle Recommendations

Beyond diet, other lifestyle factors are crucial for managing hypothyroidism symptoms:

Exercise Regularly: Helps boost metabolism, improves mood, and supports weight management.
Get Quality Sleep: Inadequate sleep can worsen fatigue and impact metabolism.
Manage Stress: Practices like yoga and meditation can help reduce stress, which can affect thyroid function.
Stay Hydrated: Drinking plenty of water supports overall health and helps combat constipation.

By combining these lifestyle habits with a thoughtful approach to nutrition, you can effectively support your health and better manage your underactive thyroid.

Frequently Asked Questions

There are very few foods you must entirely avoid, but it's recommended to limit or moderate certain categories. High-fat, processed, and sugary foods are generally discouraged, and soy should be timed carefully around medication.

Yes. High-fiber foods, soy products, coffee, and supplements containing calcium or iron can all interfere with the absorption of levothyroxine. It's crucial to take your medication on an empty stomach and separate it from these items by at least four hours.

A gluten-free diet is not necessary for everyone with hypothyroidism, but it can be beneficial for those with coexisting Celiac disease or gluten sensitivity. Always consult your doctor before eliminating gluten completely.

Selenium is crucial as it helps activate thyroid hormones and protects the thyroid from oxidative damage. Good food sources include Brazil nuts, seafood, and eggs, which are generally preferable to supplements unless a deficiency is confirmed.

Yes, but in moderation, and preferably cooked. Cooking reduces the goitrogenic compounds in cruciferous vegetables that can interfere with iodine absorption. For most people with adequate iodine, moderate intake is not a concern.

Weight management for hypothyroidism involves a combination of a healthy diet rich in whole foods, regular exercise (both cardio and resistance training), adequate sleep, and stress management. Avoiding processed and sugary foods is also key due to a slower metabolism.

Only if advised by a healthcare professional. While iodine is essential, excessive intake can be harmful and potentially worsen thyroid conditions like Hashimoto's. A balanced diet often provides sufficient iodine.