20 Foods High in Selenium: Best Sources for Thyroid, Immunity, and Antioxidant Support

Selenium is a trace mineral your body cannot make on its own, yet it drives some of your most critical biological functions. Every cell in your body depends on selenium-containing proteins called selenoproteins, which regulate thyroid hormone production, protect cells from oxidative damage, and coordinate immune responses. The National Institutes of Health identifies selenium as essential for reproductive health, DNA synthesis, and protection against oxidative stress and infection. Getting enough selenium through food is the safest and most effective strategy, since both deficiency and excess carry real health risks.

The recommended dietary allowance for adults is 55 micrograms per day, rising to 60 mcg during pregnancy and 70 mcg while breastfeeding. Despite how little you need, selenium deficiency affects an estimated one billion people worldwide due to soil depletion in many regions. Research published in Nutrients confirms that organic selenium from food, particularly in the form of selenomethionine, is absorbed more efficiently than supplements, making dietary sources your best first line of defense.

The 20 foods below are among the richest natural sources of selenium, spanning proteins, seafood, grains, dairy, and plant foods to help you build a selenium-sufficient diet no matter your eating style.

20 Foods With the Highest Selenium Content

1. Brazil Nuts: The Most Concentrated Selenium Food on Earth

Brazil nuts grow in the Amazon basin where selenium-rich soil produces nuts with extraordinary mineral concentrations. A single Brazil nut can contain anywhere from 68 to 91 micrograms of selenium, meaning one to two nuts provides your entire daily requirement. The selenium in Brazil nuts is almost entirely selenomethionine, the organic form your body absorbs most efficiently.

Harvard T.H. Chan School of Public Health notes that Brazil nuts are the most potent dietary source of selenium available, though intake should be limited to one to three per day to avoid selenium toxicity (selenosis), which can occur when intake consistently exceeds 400 mcg daily.

Best eaten: Raw or dry-roasted; one to two nuts per day is sufficient. Avoid eating a large handful daily.

Sodium is naturally negligible; salted varieties will be higher.

2. Yellowfin Tuna: A Lean, High-Selenium Protein

Yellowfin tuna is one of the richest selenium sources in the seafood category, delivering approximately 167 mcg per 3-ounce cooked serving, more than three times the daily requirement. It also provides high-quality complete protein and omega-3 fatty acids, making it a nutritionally dense choice for selenium intake.

The American Heart Association recommends eating fish like tuna at least twice a week for cardiovascular benefits, and selenium from tuna also supports thyroid enzyme activity and antioxidant defenses.

Best eaten: Grilled, seared, or canned in water; pair with vegetables to create a complete meal.

3. Oysters: A Shellfish Loaded With Selenium and Zinc

Oysters are nutritional powerhouses that deliver selenium alongside zinc, iron, and vitamin B12. A 3-ounce serving of cooked oysters provides roughly 56 mcg of selenium, just over the full daily requirement. They are one of the most micronutrient-dense foods per calorie available.

Research in the journal Nutrients highlights selenium’s role in antioxidant enzyme systems, where it works alongside other trace minerals to neutralize free radicals; oysters supply several of these co-factors simultaneously.

Best eaten: Steamed, baked, or broiled; raw oysters carry a risk of foodborne illness, particularly for immunocompromised individuals.

4. Halibut: A Mild White Fish With Impressive Selenium Content

Halibut is a lean, mild-tasting white fish that provides approximately 47 mcg of selenium per 3-ounce cooked serving. It is an excellent option for those who want selenium-rich seafood without the stronger flavor of tuna or salmon. Halibut is also a good source of magnesium, phosphorus, and niacin.

The Mayo Clinic recommends including a variety of fish in your diet for broad micronutrient coverage; halibut fits naturally into a selenium-rich eating pattern while keeping saturated fat low.

Best eaten: Baked, grilled, or poached; season simply to let its delicate flavor come through.

5. Sardines: Small Fish With a Big Selenium Punch

Sardines are one of the most affordable and sustainable selenium-rich foods available. A 3-ounce serving of canned sardines in oil provides around 45 mcg of selenium, along with omega-3 fatty acids, calcium, vitamin D, and vitamin B12. Their small size means they accumulate fewer environmental toxins than larger fish.

A study published in PMC/Nutrients found that higher dietary selenium intake is associated with reduced body fat, and sardines offer selenium alongside healthy fats that support metabolic function.

Best eaten: Straight from the can over salads, on whole-grain crackers, or mashed with lemon and herbs as a spread.

Sodium is higher in canned varieties; choose low-sodium options when available.

6. Pork Tenderloin: A Lean Red Meat With Solid Selenium Levels

Pork tenderloin is one of the leanest cuts of pork and a reliable selenium source, providing approximately 42 mcg per 3-ounce cooked serving. It is also rich in B vitamins, particularly thiamine and B6, which work alongside selenium in cellular energy metabolism.

The NIH Office of Dietary Supplements notes that meat and poultry are among the top contributors to selenium intake in the American diet, largely because the selenium content of animal feed is regulated in many countries.

Best eaten: Roasted or grilled; trim visible fat and avoid high-sodium marinades to keep it a clean protein source.

7. Turkey Breast: A Poultry Staple High in Selenium

Turkey breast delivers approximately 40 mcg of selenium per 3-ounce cooked serving, making it one of the best poultry sources of the mineral. It is also exceptionally lean and high in protein, with less than 2 grams of fat per serving.

Selenium in turkey supports glutathione peroxidase activity, the primary antioxidant enzyme system that protects cell membranes from lipid peroxidation. Research in Molecules (2025) confirms that selenoproteins like glutathione peroxidase are critical for maintaining cellular integrity under oxidative stress.

Best eaten: Roasted, sliced thin for sandwiches, or cubed into grain bowls; avoid processed deli turkey that is high in sodium and nitrates.

8. Beef (Lean Ground or Sirloin): Selenium From Animal Protein

Lean beef provides roughly 33 to 36 mcg of selenium per 3-ounce cooked serving, depending on the cut. Sirloin and extra-lean ground beef are among the better options for maximizing selenium while managing saturated fat intake. Beef also contributes iron, zinc, and B12.

The American Diabetes Association acknowledges lean beef as an appropriate protein source within a balanced diet, noting that pairing it with vegetables supports overall nutrient adequacy.

Best eaten: Grilled or pan-seared; choose 90% or leaner ground beef and trim visible fat from steaks.

9. Chicken Breast: The Everyday Selenium Source

Chicken breast is one of the most commonly consumed proteins in the world and a dependable selenium source, providing approximately 27 to 32 mcg per 3-ounce cooked serving. Its widespread availability makes it one of the most practical ways to meet daily selenium needs.

Selenium in chicken supports immune cell production and thyroid hormone conversion. Harvard Health Publishing explains that trace minerals including selenium are central to the body’s antioxidant and immune defense networks, with dietary sources consistently outperforming supplements for bioavailability.

Best eaten: Baked, grilled, or poached; skinless breast keeps saturated fat minimal.

10. Eggs: A Whole-Food Selenium Source With Added Nutrients

One large egg provides approximately 15 mcg of selenium, most of which is concentrated in the yolk. Eggs are also one of the few food sources of choline, and they provide vitamin D, B12, and complete protein. Two eggs at breakfast deliver roughly 30 mcg, more than half your daily selenium requirement.

The American Journal of Clinical Nutrition has published research supporting eggs as a highly bioavailable source of multiple nutrients, including selenium in its organic selenomethionine form, which is readily utilized by the body.

Best eaten: Scrambled, poached, or hard-boiled; whole eggs including the yolk maximize selenium content.

Per one large egg.

11. Cottage Cheese: A Dairy Source of Selenium and Protein

One cup of low-fat cottage cheese provides approximately 20 mcg of selenium along with 25 grams of protein, making it a high-value food for selenium intake. Dairy products in general contribute meaningfully to selenium intake because selenium content in milk reflects the selenium status of the cattle’s feed.

The Mayo Clinic recognizes cottage cheese as a nutrient-dense food that supports satiety and muscle maintenance; its selenium content adds an additional micronutrient benefit often overlooked.

Best eaten: As a snack with fruit, stirred into smoothies, or used as a high-protein base for savory bowls.

Per 1 cup (low-fat); choose low-sodium varieties if sodium is a concern.

12. Brown Rice: A Plant-Based Selenium Source

Brown rice provides approximately 19 mcg of selenium per cooked cup, making it one of the better plant-based selenium sources available. Its selenium content reflects the soil in which the rice was grown; rice from selenium-rich regions can be significantly higher in content.

Research from the NIH confirms that whole grains including brown rice contribute meaningfully to selenium intake in populations that do not eat large amounts of meat or seafood, serving as a staple selenium source in many Asian countries.

Best eaten: As a base for grain bowls, stir-fries, or alongside lean proteins; cooking in low-sodium broth adds flavor without processed additives.

Per 1 cup cooked.

13. Sunflower Seeds: A Selenium-Rich Snack

One ounce of dry-roasted sunflower seeds delivers approximately 23 mcg of selenium, along with vitamin E, magnesium, and healthy fats. Sunflower seeds are a practical snack for plant-forward eaters looking to boost selenium intake without relying on animal products.

Selenium and vitamin E work synergistically as antioxidants: selenium activates glutathione peroxidase while vitamin E quenches lipid radicals in cell membranes. This antioxidant partnership is documented in Antioxidants (2022), which highlights how co-occurring nutrients in whole foods enhance selenium’s protective effects.

Best eaten: As a snack, sprinkled on salads or oatmeal, or blended into sunflower seed butter.

Per 1 oz dry-roasted, unsalted.

14. Whole Wheat Bread: An Everyday Selenium Contributor

Two slices of whole wheat bread provide approximately 16 mcg of selenium, a meaningful contribution for people who eat bread regularly. Like brown rice, the selenium content of wheat depends heavily on soil conditions, but commercially produced whole wheat in North America tends to be a reliable source.

Whole grains also provide fiber, B vitamins, and magnesium that support the metabolic pathways in which selenium-dependent enzymes operate. Eating selenium-containing foods alongside other micronutrients enhances the functional impact of the mineral.

Best eaten: As toast, sandwiches, or alongside soups; choose 100% whole wheat with minimal added sugar and sodium.

Per 2 slices; sodium varies by brand.

15. Shrimp: A Low-Calorie Seafood High in Selenium

Shrimp provides approximately 40 mcg of selenium per 3-ounce cooked serving despite being extremely low in calories and fat. It is one of the most selenium-efficient foods by calorie, meaning you get substantial micronutrient value without a significant caloric investment.

The American Heart Association includes shrimp as a recommended seafood option when prepared without heavy sauces or frying; it fits well into weight-conscious eating plans that also require strong micronutrient coverage.

Best eaten: Steamed, sautéed with garlic and olive oil, or added to pasta, rice bowls, and salads.

16. Mushrooms (Cremini or Portobello): The Plant Kingdom’s Selenium Champion

Cremini and portobello mushrooms are among the richest plant-based selenium sources, providing approximately 18 to 26 mcg per cup cooked, depending on the variety and growing conditions. They are also one of the few plant foods that naturally contain vitamin D when exposed to UV light.

Mushrooms accumulate selenium from the substrate they grow in; commercially grown varieties are often cultivated on selenium-enriched growing media. Research cited by The NIH identifies mushrooms as one of the top plant sources of selenium for vegetarian and vegan eaters.

Best eaten: Sautéed, roasted, grilled, or added to soups, grain bowls, and pasta dishes.

Per 1 cup cooked cremini mushrooms.

17. Canned Tuna (Light): An Affordable, Accessible Selenium Source

Canned light tuna is one of the most budget-friendly ways to meet your daily selenium needs. A 3-ounce serving provides approximately 68 mcg of selenium, well over the daily requirement, at a fraction of the cost of fresh fish. Light tuna (typically skipjack) is lower in mercury than albacore and considered safer for more frequent consumption.

The Food and Drug Administration advises that adults can safely eat 2 to 3 servings of light canned tuna per week, making it a practical selenium strategy for those on a budget.

Best eaten: Mixed with avocado or Greek yogurt instead of mayonnaise, over salad greens, or in whole wheat wraps.

Sodium varies by brand; choose low-sodium or no-salt-added varieties.

18. Lentils: A Legume With Modest but Meaningful Selenium

One cooked cup of lentils provides approximately 6 mcg of selenium, a modest but meaningful amount for plant-based eaters who eat them regularly. Lentils also deliver folate, iron, potassium, and 18 grams of protein per cup, making them one of the most nutritionally complete legumes available.

While lentils are not a high-selenium food in isolation, they contribute to overall selenium intake when eaten frequently as part of a varied plant-forward diet. Combining lentils with other plant selenium sources like mushrooms, sunflower seeds, and whole grains helps vegetarians reach adequate daily intake.

Best eaten: In soups, stews, curries, or as a base for grain bowls; red lentils cook faster and work well in pureed soups.

Per 1 cup cooked.

19. Low-Fat Milk: A Daily Selenium Contributor

One cup of low-fat milk provides approximately 8 mcg of selenium, a quiet but consistent contribution for people who consume dairy daily. Across the course of a week, regular milk consumption adds up to a meaningful selenium contribution alongside calcium, vitamin D, potassium, and riboflavin.

The NIH Office of Dietary Supplements identifies dairy products as one of the primary everyday selenium sources for adults in the United States and other countries with selenium-replete livestock practices.

Best eaten: In coffee, smoothies, oatmeal, or as a standalone drink; plain low-fat or fat-free milk maximizes the selenium-to-calorie ratio.

Per 1 cup (8 oz) low-fat milk.

20. Spinach: A Dark Leafy Green With Trace Selenium

Cooked spinach provides approximately 3 to 4 mcg of selenium per cup, a small but additive contribution for people who eat leafy greens daily. Spinach is primarily valued for folate, iron, vitamin K, and lutein, but its selenium content makes it part of a well-rounded plant-based selenium strategy.

Like all plant foods, spinach selenium content is tied directly to soil quality. Organic and locally grown spinach from selenium-rich regions may contain higher amounts. Eating spinach alongside selenium-richer foods reinforces the body’s antioxidant defenses through complementary nutrient pathways.

Best eaten: Sautéed with garlic and olive oil, wilted into soups, or added raw to smoothies for a nutrient boost without a strong flavor impact.

Per 1 cup cooked.

Summary: Top 20 Selenium Foods at a Glance

Tips for Getting the Most Selenium From Food

Vary your protein sources. Rotating between seafood, poultry, eggs, and legumes ensures you hit your selenium target while also diversifying your intake of omega-3s, iron, zinc, and other micronutrients that work alongside selenium.

Don’t overdo Brazil nuts. One to two Brazil nuts per day is all you need to meet your daily requirement. Eating a full handful regularly risks selenium toxicity, which can cause hair loss, brittle nails, nausea, and neurological symptoms.

Choose whole grains over refined. Brown rice and whole wheat bread deliver significantly more selenium than their white counterparts because selenium is concentrated in the bran and germ layers removed during refining.

Combine plant sources strategically. No single plant food meets the daily selenium requirement alone. If you eat plant-forward, pairing mushrooms, sunflower seeds, whole grains, and legumes across the day adds up to adequate intake.

Cooking method matters less than you think. Selenium is relatively stable during cooking, though some water-soluble selenium can leach into boiling water. Steaming, roasting, and grilling preserve selenium content better than boiling.

Consider soil variability. Selenium in plant foods depends entirely on soil content. If you live in a low-selenium region (parts of Europe, China, and New Zealand), emphasizing animal proteins and seafood helps compensate for plant food variability.

The Bottom Line

Selenium is a small mineral with an outsized role in your health, driving thyroid function, antioxidant enzyme activity, immune defense, and reproductive health. Meeting the 55 mcg daily requirement is achievable through a varied diet that includes seafood, lean meats, eggs, dairy, whole grains, mushrooms, and nuts. Brazil nuts stand apart as the single most concentrated source, though moderation is essential. For most people, eating two to three servings of selenium-rich foods daily, with an emphasis on seafood and lean proteins, is enough to maintain optimal selenium status without the risk that high-dose supplementation carries.

Nutrition data sourced from the USDA FoodData Central database. Individual values may vary based on food preparation, origin, and growing conditions. This article is for informational purposes only and does not constitute medical advice. Consult a qualified healthcare provider before making significant dietary changes, particularly if you have a thyroid condition, are pregnant, or are considering selenium supplementation.