Probiotic strains are a type of live microorganism that helps to improve the health and well-being of your intestinal tract. Yogurt, kefir, kombucha, sauerkraut, and miso soup are just some of the food items and supplements that contain probiotic strains. These organisms help in maintaining the balance of good bacteria in your intestines and help to protect against harmful pathogens such as Escherichia coli. They also aid in digestion by separating out individual nutrients in food for the body to use.