Selenium is a trace mineral that is vital to your antioxidant defense system. Without it, several enzymes your body uses to destroy free radicals don’t function properly. The incidence and mortality rates of numerous cancers are higher in those with low levels of selenium. And adequate selenium levels also reduce the risk of heart disease, increase immunity, and dramatically boost male fertility.

But there’s a good chance you’re deficient in this vital mineral. That’s because the amount of selenium in foods is dependent on the amount of it in the soil. And because most of the nutrients in our soils have been depleted, so have the nutrients in most of our vegetables. But there is one highly potent and very convenient source of vital selenium: Brazil nuts.

In fact, one unshelled Brazil nut has an average of 100 mcg of selenium. That’s more than what is in most mineral supplements. Brazil nuts that you buy already shelled are a good source of selenium too, but only have an average of 15 to 20 mcg per nut. So you would need to eat from five to seven of them to get the same amount of selenium you can get in one unshelled nut.