magnesium (500 mg—125% DV), phosphorus (946 mg—96% DV), copper (2.3 mg—116% DV), and manganese (1.6 mg—81%), [14] and are perhaps the richest dietary source of selenium ; one ounce can contain as much as 10 times the adult USRDA (U.S. Recommended Dietary Allowances ), more even than the Tolerable Upper Intake