Flora are healthy microbes and bacteria that live in the gut and other passageways in the body. They are essential to maintaining a strong immune system to fight colds, flu, and ear infections. In fact, 75% of the human immune system resides in the gut. This flora also protects the lining of the gut (intestine), allowing for the proper absorption of nutrients. Perhaps even more important, a healthy flora prevents absorption of large, foreign molecules through the lining of the intestines into the bloodstream. These are not meant to be absorbed, and can cause an allergic reaction through Leaky Gut Syndrome.