Seleni-what? You’ve probably never heard of this essential trace mineral, which your body only needs in small amounts (just a "trace"). Here’s the catch: the amount of selenium in any food depends on how much is in the soil where that food was grown or raised, so it varies. If you eat a diet that includes Brazil nuts, (selenium superstars), fish and shellfish, pork, beef, turkey, eggs, sunflower seeds, brown rice, and spinach, you probably get plenty of selenium. There are some cases, though, where supplements of this trace mineral are very helpful. Low selenium can also be a factor in chronic diseases, including metabolic syndrome, and you definitely want to correct a deficiency or insufficiency if you have one.