They say big things come in small packages, and the same is true for selenium. Known as a trace mineral because it’s needed in only scant amounts, selenium is found primarily in plants, particularly from soil that’s rich in the element, and in some meats and nuts. While it may seem minor to be deficient in a trace mineral, it can have major consequences.

Selenium is a powerful antioxidant that combats the damage that free radicals cause in the body, and it can improve cardiovascular health and fight cancer as well. It also plays a role in thyroid health, assisting with the metabolism of iodine and the production of critical thyroid hormones.

Since the thyroid controls the body’s metabolism, keeping it in good working order is essential to maintaining a lean physique. But selenium can also impact that lean physique by increasing muscle strength. In a study published in The American Journal of Clinical Nutrition, researchers measured hip flexion, leg extension and grip strength in 891 subjects, and found that those who had high selenium levels were more likely to be stronger than those with lower selenium levels.

While taking supplemental selenium is the best way to ensure you get adequate amounts, it’s not entirely necessary to add another pill to your supplement regimen. Brazil nuts are known to include as much as 95 mcg of selenium per nut. Given that the RDA for selenium is 55 mcg and we recommend getting 200 mcg daily, just a couple of Brazil nuts could have you set.

Since megadoses of selenium can negatively impact your health, take no more than 400 mcg per day, the upper limit set by the National Academy of Sciences Institute of Medicine (Washington, D.C.). In another nod to Brazil nuts, New Zealand researchers found that eating them was just as effective at raising selenium levels as taking a supplement. The scientists gave subjects either 100 mcg of selenium from a supp, 100 mcg of selenium through Brazil nuts or a placebo. After 12 weeks, the subjects taking the supplement or eating the nuts had blood levels of the mineral that were 60% higher. Both groups also showed increased blood levels of glutathione peroxidase, a critical antioxidant enzyme that depends on selenium to function properly.

Brazil nuts aren’t the only source of selenium, just one of the best. Wherever you get your selenium, make sure you’re getting enough.

Seeking Selenium? The best sources of the mighty mineral:

Food Amount Selenium, Content (mcg)

  • Brazil nuts, dried, unblanched 1 oz. (about 6) 544
  • Tuna, light, canned in oil 3 oz. 63
  • Beef, cooked 3.5 oz. 35
  • Cod, cooked 3.5 oz. 32
  • Turkey, light meat, roasted 3.5 oz. 32
  • Beef, chuck roast, roasted 3.5 oz. 23
  • Chicken breast, roasted 3.5 oz. 20
  • Macaroni, boiled 1⁄2 cup 15
  • Egg 1 medium 14
  • Low-fat (2%) cottage cheese 1⁄2 cup 12
  • Instant oatmeal, cooked 1 cup 12
  • Brown rice, cooked 1⁄2 cup 10
  • Whole-wheat bread 1 slice 10
  • Cheddar cheese 1 oz. 4

* adapted from the National Institutes of Health Office of Dietary Supplements