Is that one year from date of manufacture or one year after openeing since shelf life is often defined as from one of these events? If it is one year after date of manufacture than it is possible to purchase a product that has expired because it is not uncommom for products to sit ih supplier's warehouses for quite a while before making it into a store's inventory and the product might also sit in a retails store's warehouse before making it onto the shelf (not to mention how long it might sit on the shelf before it is sold!)