What fish helps the thyroid? A guide to nutrient-rich seafood

December 24, 2025 •

4 min read

The thyroid gland relies on specific nutrients to function correctly, with studies showing that consuming nutrient-dense foods can support its health. Understanding what fish helps the thyroid by providing crucial elements like iodine, selenium, and omega-3 fatty acids is an effective dietary strategy.

Quick Summary

Several fish varieties, particularly fatty fish like salmon and leaner options such as cod, offer key nutrients like iodine and selenium that are vital for proper thyroid function.

Key Points

Fatty Fish Are Key: Salmon, mackerel, and sardines are rich in anti-inflammatory omega-3 fatty acids, which benefit autoimmune thyroid conditions like Hashimoto's.
Lean Fish for Iodine: Cod is a prime source of iodine, a crucial mineral for producing thyroid hormones, with a single serving providing a significant portion of the daily requirement.
Selenium Supports Conversion: Fish like tuna and sardines are excellent sources of selenium, which helps convert inactive thyroid hormone (T4) into its active form (T3).
Watch Mercury Levels: Smaller, oily fish like sardines and wild salmon have low mercury levels, while larger predatory fish like swordfish should be consumed in moderation.
Cook Smart: Baking, grilling, or steaming fish helps retain maximum nutrients compared to frying, ensuring you get the full benefits for your thyroid.
Dietary Balance: Including a variety of fish in your diet ensures a balanced intake of the different nutrients—iodine, selenium, and omega-3s—needed for optimal thyroid health.

The Importance of Fish for Thyroid Function

The thyroid is a butterfly-shaped gland located in the neck that produces hormones essential for regulating metabolism, energy levels, and growth. For the thyroid to produce hormones effectively, it requires a steady supply of specific nutrients. Two of the most critical are iodine and selenium. Fish and other seafood are among the best dietary sources for both of these minerals, as well as providing anti-inflammatory omega-3 fatty acids that benefit autoimmune thyroid conditions like Hashimoto's thyroiditis.

Iodine: Fuel for Hormone Production

Iodine is a building block for thyroid hormones, and a deficiency can lead to hypothyroidism and goiter. Many fish naturally absorb iodine from the seawater they live in, making them excellent sources.

Cod: This lean, white fish is a standout source of iodine. Just three ounces of cod can provide over half of the daily recommended intake. It is also low in fat and calories, making it a healthy option for regular consumption.
Shrimp and Shellfish: As they absorb minerals from their marine environment, shrimp and other shellfish are also reliable sources of iodine, along with other nutrients like vitamin B12 and phosphorus.

Selenium: The Thyroid's Antioxidant Guardian

Selenium is a powerful antioxidant that helps protect the thyroid from oxidative damage and plays a crucial role in converting the inactive T4 thyroid hormone into its active form, T3. A deficiency in selenium has been linked to thyroid dysfunction.

Tuna: Both fresh and canned tuna are great sources of selenium. A three-ounce serving of tuna can provide a significant portion of your daily selenium needs. However, as tuna is a larger, predatory fish, it may contain higher levels of mercury, so moderation is key.
Sardines: These small, oily fish are packed with both selenium and calcium (if consumed with bones). Sardines also offer omega-3s, making them a very efficient nutritional choice.

Omega-3s: Fighting Inflammation

For individuals with autoimmune thyroid conditions, such as Hashimoto's, inflammation is a major concern. Omega-3 fatty acids, found in fatty fish, have potent anti-inflammatory properties that may help manage symptoms and reduce inflammation in the thyroid gland.

Salmon: A true champion for thyroid health, salmon is rich in omega-3s (EPA and DHA), selenium, and iodine. It helps reduce inflammation and is a high-quality protein source essential for hormone synthesis. Wild-caught salmon generally has higher omega-3 levels and lower contaminants than farmed salmon.
Mackerel: Like salmon, mackerel is a fatty fish that is an excellent source of omega-3s, selenium, and iodine. It provides a valuable protein source and is also rich in vitamin D, another nutrient linked to thyroid health.

Fish for Thyroid Health: A Comparison


Feature	Cod	Salmon	Tuna	Sardines	Mackerel
Primary Benefit	High Iodine	Omega-3s, Selenium	High Selenium	Selenium, Calcium	Omega-3s, Selenium
Iodine Content	Very High	Good	Good	Present	High
Selenium Content	Good	Excellent	Excellent	Excellent	Excellent
Omega-3s	Low	Very High	Good	Very High	Very High
Mercury Risk	Low	Low (Wild)	Moderate/High	Very Low	Low

Balancing Benefits and Risks: The Mercury Factor

While fish is generally excellent for thyroid health, some varieties contain higher levels of mercury, a heavy metal that can negatively impact the thyroid and nervous system. Larger, predatory fish like swordfish and large tuna tend to accumulate more mercury than smaller, fatty fish. The key is to make smart choices and consume a variety of fish in moderation.

Smart choices: Favor smaller fish like sardines, mackerel, and wild-caught salmon. These offer high nutritional value with a lower risk of mercury contamination.
Moderate intake: For larger fish like tuna, limiting intake to a few times per week is a good strategy, especially for pregnant women and children.

How to Incorporate Thyroid-Friendly Fish into Your Diet

Including these fish in your weekly meals is simple and delicious. Here are a few suggestions:

Breakfast: Add canned sardines or salmon to an omelet for a protein and nutrient boost.
Lunch: Make a tuna or salmon salad sandwich or top a green salad with grilled cod.
Dinner: Bake or grill salmon or mackerel with a squeeze of lemon and some dill. Cod can be baked, pan-seared, or used in fish tacos.
Snacks: Canned sardines or salmon straight from the can are a convenient, nutrient-dense snack.

Cooking Methods for Maximum Benefit

How you prepare your fish can also impact its health benefits. Frying can reduce the omega-3 content, while baking, grilling, and steaming are generally healthier options that preserve more nutrients.

Conclusion: Making Informed Choices for Your Thyroid

Incorporating specific fish into your diet is a highly effective way to support your thyroid's function by providing essential nutrients like iodine, selenium, and omega-3 fatty acids. Fatty fish such as salmon and mackerel offer powerful anti-inflammatory benefits, while lean fish like cod are an excellent source of iodine. By prioritizing smaller, fatty fish and consuming larger predatory fish in moderation, you can leverage the significant health advantages that seafood provides for your thyroid and overall well-being. Always consult a healthcare provider for personalized advice, especially if you have a pre-existing thyroid condition. For more detailed information on omega-3 fatty acids and thyroid health, an article from the National Institutes of Health provides further insights.

Frequently Asked Questions

For Hashimoto's, fatty fish like salmon, sardines, and mackerel are particularly beneficial due to their high omega-3 fatty acid content, which helps reduce inflammation often associated with this autoimmune condition.

Yes, canned tuna is a good source of selenium, a vital mineral for thyroid hormone conversion. However, because tuna can have higher mercury levels than smaller fish, it should be eaten in moderation.

Fish oil supplements can provide a concentrated dose of omega-3s, but whole fish offer a wider range of essential nutrients, including iodine and selenium, as well as high-quality protein. It's often better to get nutrients from whole food sources when possible, but supplements can be a useful addition after consulting a doctor.

There is no single recommendation for all individuals, but many health guidelines suggest consuming fatty fish two to three times per week. A variety of fish is generally recommended to ensure a broad spectrum of nutrients.

Most saltwater fish and seafood contain some level of iodine, as they absorb it from the ocean. Leaner fish like cod tend to have higher concentrations than fattier fish, though the amount can vary.

For those concerned about mercury, it's wise to limit consumption of large, predatory fish such as swordfish and king mackerel. Otherwise, most fish offer benefits, but consulting a doctor is recommended if you have a specific thyroid condition.

Excessive intake of certain types of fish, particularly those high in mercury, can potentially harm thyroid function over time. As with any food, moderation and variety are key to balancing benefits and risks.