What Nuts Are Not Good for the Thyroid?

December 18, 2025 •

4 min read

While nuts are celebrated for their health benefits, certain types contain compounds that can negatively affect thyroid function or medication absorption. For individuals with thyroid concerns, being mindful of these particular nuts can be an important step towards managing their health effectively. This guide sheds light on the nuts you might want to approach with caution.

Quick Summary

This article discusses nuts to consume cautiously with thyroid conditions, such as walnuts, peanuts, and pine nuts, due to their goitrogenic content or interference with medication absorption.

Key Points

Walnuts and Medication: Walnuts can interfere with the absorption of thyroid medication, so consume them at least four hours away from taking your dose.
Goitrogens in Peanuts and Pine Nuts: Peanuts and pine nuts contain goitrogens, compounds that can inhibit thyroid function, especially with excessive intake or iodine deficiency.
Moderation is Key: Most nuts are safe in moderation; the risks from goitrogens and fiber are mainly linked to high, frequent consumption.
Brazil Nuts Boost Thyroid: Brazil nuts are rich in selenium, a vital mineral for thyroid health, but limit intake to a few per day to avoid toxicity.
Soy Nuts as an Alternative: Soy nuts (technically a legume) contain goitrogenic isoflavones and should be consumed in moderation, particularly if you have an iodine deficiency.
Consult a Professional: Always talk to your doctor or a dietitian about your diet, especially if you have a thyroid condition or take medication.

Understanding the Thyroid and Nuts

The thyroid is a small gland at the base of your neck that produces hormones crucial for regulating metabolism, growth, and energy. When its function is compromised, as with conditions like hypothyroidism or hyperthyroidism, managing your diet becomes a key part of your treatment plan. Some foods, including certain nuts, contain compounds that can influence thyroid hormone production or interfere with the effectiveness of thyroid medication.

The Problem with Goitrogenic Nuts

Goitrogens are natural substances found in some foods that can interfere with the thyroid gland's ability to use iodine properly. Iodine is an essential building block for thyroid hormones, so foods high in goitrogens can disrupt this process. For people with existing thyroid issues, particularly those with iodine deficiency, consuming large amounts of raw goitrogenic foods can exacerbate their condition.

Peanuts

Peanuts are one of the most commonly cited nuts (technically a legume) that contain goitrogenic compounds. While you don't have to eliminate them entirely, excessive or frequent consumption is discouraged, especially for those with hypothyroidism. Many experts suggest that moderation is key and that roasting or cooking peanuts can reduce the goitrogenic effect. Peanut butter, unless it's a small serving, should also be consumed with caution for the same reasons.

Pine Nuts

Similar to peanuts, pine nuts are also mentioned as containing potential goitrogenic compounds. People with hypothyroidism are often advised to limit their intake of pine nuts. Again, moderation is the general consensus, and including a variety of other nuts in your diet is recommended.

Nuts That Interfere with Medication

For many people with hypothyroidism, daily medication is a lifelong necessity. The timing of when you eat can significantly impact how well your body absorbs this medication. Some nuts contain high levels of dietary fiber that can interfere with the absorption of synthetic thyroid hormones like levothyroxine.

Walnuts

Walnuts are particularly known for interfering with the absorption of thyroid hormone medication. The manufacturer of Synthroid, a leading levothyroxine brand, specifically warns about this interaction. To prevent this, it is recommended to take your thyroid medication on an empty stomach and wait at least four hours before eating walnuts or other high-fiber foods. This practice ensures your body can properly absorb the medication before dietary components interfere.

High-Fiber Nuts

Beyond walnuts, other nuts high in dietary fiber could potentially have a similar, though perhaps less pronounced, effect on medication absorption. While fiber is an important part of a healthy diet, it can bind to medications and prevent them from being fully absorbed. The strategy of spacing out medication and food consumption is a safe bet for many nuts.

Comparison Table: Nuts and Thyroid Health


Nut Type	Potential Thyroid Issue	Recommended Approach
Peanuts	Goitrogenic effect (especially raw)	Consume in moderation; cooking may reduce effect.
Pine Nuts	Goitrogenic effect	Consume in moderation; limit with hypothyroidism.
Walnuts	Interferes with medication absorption	Avoid eating within 4 hours of taking thyroid medication.
Brazil Nuts	Contains high selenium (beneficial)	Excellent for thyroid health, but limit to 1-3 daily to avoid selenium toxicity.
Macadamia Nuts	High in selenium (beneficial)	Safe and beneficial in moderation.
Almonds & Cashews	Good source of minerals	Safe and beneficial for most individuals.

Nuts That Are Good for the Thyroid

Not all nuts are cautionary for the thyroid; some are highly beneficial. Brazil nuts are a standout, containing exceptionally high levels of selenium, a mineral vital for thyroid hormone production and antioxidant protection. Just one to two Brazil nuts per day can provide the necessary selenium without causing toxicity. Macadamia nuts and hazelnuts are also good sources of selenium and can be enjoyed as part of a balanced diet.

Important Considerations

For most people with healthy thyroid function, consuming any of these nuts in moderation will not cause issues. The primary concerns apply to individuals with pre-existing thyroid conditions, especially hypothyroidism, or those on thyroid replacement medication. Always consult your doctor or a registered dietitian before making significant changes to your diet. They can help you create a meal plan that supports your thyroid health without unnecessary restrictions.

Conclusion

While nuts offer a wealth of nutrients, it's wise for individuals with thyroid issues to be aware of the potential effects of certain types. Limiting high-goitrogen nuts like peanuts and pine nuts, and timing your medication intake to avoid interaction with walnuts, are simple yet effective strategies. Incorporating selenium-rich nuts like Brazil nuts in small quantities can also provide a boost to thyroid health. By making informed choices, you can continue to enjoy the benefits of nuts while actively supporting your thyroid function.

Disclaimer: This information is for educational purposes only and should not be considered medical advice. Always consult with a qualified healthcare professional before making dietary changes, especially if you have a thyroid condition. For more information on goitrogens and thyroid health, see Kresser Institute on Goitrogenic Foods.

Frequently Asked Questions

Yes, but in moderation. Peanuts contain goitrogens, which can affect thyroid function when consumed in large, raw quantities, particularly if you have an iodine deficiency. Cooking peanuts may reduce the goitrogenic effect.

Walnuts, along with other high-fiber foods, can interfere with the body's absorption of synthetic thyroid hormone medication (like levothyroxine). To prevent this, it is best to separate your walnut consumption by at least four hours from when you take your medication.

Pine nuts, like peanuts, contain goitrogenic compounds. While small amounts are likely fine for most people, those with hypothyroidism should consider limiting their intake.

The fiber itself is not 'bad,' but high fiber content can interfere with medication absorption. The issue lies with the timing of consumption relative to your medication, not the nut itself. Most nuts are safe when consumed away from your dose.

Almonds and cashews are generally considered safe and beneficial for thyroid health. They are good sources of healthy fats, protein, and minerals like zinc, which support overall thyroid function.

Yes, cooking can help reduce the goitrogenic properties of some foods, including certain nuts. For instance, roasting peanuts is thought to decrease their goitrogenic compounds compared to eating them raw.

Yes, Brazil nuts are highly beneficial due to their high selenium content, a mineral crucial for thyroid function. However, limit intake to one to three nuts daily to prevent selenium toxicity.