Selenium in vegetables, milk, and meat is a highly bioavailable source for humans; further, foods that are intentionally Se enriched can significantly enhance the consumption of Se by humans where Se intake would be otherwise suboptimal. Selenium concentration in milk can be easily manipulated by altering Se supply to dairy cows. Transfer in milk of Se from yeast is more efficient than from inorganic sources, such as sodium selenite/selenate. There is a U-shaped risk response to Se intake, wherein supra-nutritional intakes (i.e., intakes greater than those recommended to meet metabolic requirements) can in some instances increase the risk of disease in individuals with adequate Se status. A better understanding of the interacting factors that affect bioavailability and metabolism, including the effects of Se form, con-current nutritional factors, and physiological state, will be important in establishing more refined recommendations for Se intakes.