This document discusses 5 foods that can strengthen the immune system: broccoli, garlic, fish like tuna and sardines, beef, and mushrooms. Broccoli, garlic, and fish contain nutrients like vitamins, minerals, and omega-3 fatty acids that reduce inflammation and boost white blood cell production. Beef and mushrooms provide zinc and compounds that increase white blood cell activity and productivity. Maintaining a balanced diet with these foods can help the immune system fight diseases and infections.