Foods that contain selenium include Brazil nuts, brewer’s yeast, wheat germ, garlic, grains, sunflower seeds, walnuts, raisins, and seafood. Seafood like tuna and halibut are sources of selenium, but can also contain heavy metals like mercury. Also, note that while fruits and vegetables can contain selenium, they only absorb it, but don’t produce it. This means that the actual amount of selenium in any particular fruit or vegetable depends on the selenium content of the soil in which it is grown. If the selenium content in the soil is low, it will be in the food as well. Since you’re unlikely to know the selenium content of where your food is grown, that’s another reason to take a supplement.