According to Dr. James Jay, a food biologist at the University of Nevada, Las Vegas, most foods can be safely eaten beyond the expiration date without making a person sick. The exceptions to this are meats, poultry, fresh foods that are perishable and infant formula, which is regulated by the government.
Dr. Jay claims that the general public misunderstands expiration dates. Food expiration dates are not about health safety. Instead, these dates help food manufacturers provide consumers with the best quality products.
Food producers and manufacturers are highly concerned over the quality of their product, but this has more to do with appearance and flavor than safety. According to Dan Charles of NPR, the use-by date indicates the level of deterioration of the food item as it pertains to taste and coloring, and the sell-by date exists to alert grocery stores when to clear a product off the shelves to prevent consumers from purchasing food that has lost some quality. Companies figure that consumers are less likely to buy products when they are not at their very best.
According to the Huffington Post, food becomes a health risk when dangerous bacteria contaminates it at some point during processing. This is why food that has not expired can still cause people to get sick. It is the bacteria that is the real culprit, which has nothing to do with expiration dates.