Bottom of the box. The production date of Kevin Leffron Gold Whey Protein Powder can be seen at the bottom of the product packaging box. Kevin Lefron Gold Whey Protein Powder is the most important nutrient to ensure the health of the body. It is necessary to maintain and repair the body and the growth of cells. It not only affects the growth of body tissues such as muscles, but also participates in the production of hormones, the maintenance of immune function, the transport of other nutrients and oxygen, the production of hemoglobin and blood coagulation.