They always said here (I hope it did not change) get L-Selenomethionine. I have the NOW brand and it says.
Selenium is an essential trace mineral that is found naturally in Brazil nuts, organ meats, seafood and wheat germ.
Selenium may reduce the risk of certain cancers. Some scientific evidence suggests that consumption of selenium may reduce the risk of certain forms of cancer. However, FDA has determined that this evidence is limited and not conclusive.
As a dietary supplement, take one Vcap daily, preferably with meals.
Rice flour, cellulose (capsule) and magnesium stearate (vegetable source).
Contains no sugar, salt, starch, yeast, wheat, gluten, corn, soy, milk or preservatives
Caution: Persons living in areas of high soil selenium, such as the Dakotas, should consult a physician prior to use.