Most packages of food include a sell-by or use-by date that helps stores and consumers know how long each item is safe for consumption. Eating foods that have expired might increase your risk for certain illnesses or conditions. If you are unsure whether you should eat something that has expired, err on the side of caution and toss it. Foods that have an offending odor, flavor or appearance should not be eaten, the USDA Food Safety and Inspection Service says.
Foods eaten as soon as possible after purchase often taste better than older foods, and they might also be more nutritious as well. Sari Edelstein notes in her book, "Nutrition in Public Health: A Handbook for Developing Programs and Services," that eating food past its prime is often less nutritious than eating food when it is fresh. If you regularly eat food that has expired, you might be missing out on key nutrients. Even if the nutrition label indicates that a food is nutritious, it might not contain as much of each nutrient as the label suggests.
Uncooked meats and eggs are the usual suspects when it comes to food poisoning, but any food that has expired might lead to a growth of the bacteria that can lead to food-borne illness. Food poisoning occurs when you consume dangerous bacteria that are able to grow more easily on expired foods. This is most likely to occur with perishable foods such as beef, chicken, eggs and prepared foods such as macaroni salad or potato salad. If your food has expired, it might be healthier and safer to just throw it away.
Eating food that has expired might not cause a serious illness such as food poisoning, but it might cause physical discomfort, such as an upset stomach that might or might not be accompanied by vomiting. Gas and bloating are additional symptoms that can occur if you eat expired food. The USDA Food Safety and Inspection Service reports that moldy foods can cause allergies or respiratory distress, but some moldy foods can lead to illness. It is always safer to throw the food away rather than cutting off the mold and eating it anyway.
Even if the expired food you eat is safe for consumption, it might not taste as good as if you ate it sooner. As time passes, the quality of the food declines, which decreases the taste. The USDA Food Safety and Inspection Service notes that many expired foods can be safe to eat, but they might not be as flavorful as if you ate them before the expiration date.