1. Selenium is an essential antioxidant nutrient that is present in foods in different forms with varying bioavailability and interactions with other compounds. 2. Studies show that increasing selenium levels in broccoli through fertilization decreases the plant's content of beneficial antioxidants like sulforaphane, and that the different forms of selenium from foods like broccoli and meat are incorporated into the body differently. 3. There are complex interactions between selenium, sulforaphane, and other compounds in regulating antioxidant enzymes, with higher induction occurring through combined effects rather than single nutrients alone.