There has been a lot of talk lately about the good bacteria in certain foods.  They are called pro biotic, and as the pro prefix indicates, they are, indeed, good for you.  Pro biotic are alive microorganisms that found in food or supplements that promote health.
Trillions of bacteria, many of which protect you from disease, already live in your gut.  When the balancing act between the good and the bad gets thrown off, your health can suffer.  This upset can occur when you take antibiotics, which kill off friendly, along with unfriendly, bacteria.  They may also cause gas, cramping and diarrhea.
An analysis of studies also found that chronic conditions, such as irritable bowel syndrome, ankylosing spondylits and rheumatoid arthritis, may be associated with fewer friendly bacteria in the gut.  Pro biotic foods help replace the good bacteria that have been destroyed by medications or illness.