OPTIMUM NUTRITION CASEIN 4LBCasein, a slower digesting and absorbing protein can be used after exercise, between meals or before bed to help support satiety and muscle recovery. GOLD STANDARD 100% CASEIN™ delivers BCAAs to recovering muscles for several hours. By using only premium micellar casein as a protein source, we’ve created a protein powder that sets the GOLD STANDARD® for slow digesting protein support.