These little freeloaders are bacteria, fungi, and viruses, and they make a home for themselves from our mouth, all the way to our anus. It might seem scary, but it really isn't. This extremely dynamic interaction of single cell life is known as the human gut ecosystem and it is one of the most fascinating, yet fragile environments discovered. These space invaders are constantly kept at bay by the good guys.
Friendly bacteria do much more than just fight potentially harmful organisms.
These beneficial microbes also produce chemicals that stimulate the immune system and ward-off the chances of infection. So it's obvious that friendly bacteria do much more than just hang-on for a free ride. Prevention with Probiotics Unfortunately, friendly bacteria often fall victim to a variety of factors which kill them. When the internal levels of friendly bacteria fall, harmful bacteria and fungi become more dominant. This condition is known as dysbiosis.