Selenium helps build up white blood cells, boosting your body's ability to fight illness and infection. Selenium also helps with the following. Much of your selenium comes from dietary sources. Brewer's yeast and wheat germ, liver, butter, fish and shellfish, garlic, grains, sunflower seeds, and Brazil nuts are all good sources of selenium. It's also found in alfalfa, burdock root, catnip, fennel seed, ginseng, raspberry leaf, and yarrow.
Selenium is destroyed when foods are refined or processed.
You should try eating a wide variety of whole, unprocessed foods. This means eating foods in their original state, not canned, frozen, or commercially prepared. Your health care provider may recommend that you add selenium to your diet. You can do this by taking a vitamin-mineral supplement, a nutritional antioxidant formula, or a separate supplement. Selenium is also available in nutritional yeast.