Many are convinced, and I think it's probably true, that bacteria in the gut (GI tract) are very important to health. I'm hearing there are normally something like 500-1000 species there. Antibiotics due horrible damage to them, of course. And who has never taken an antibiotic? The population of the gut with these great bacteria begins with what the infant gets from his/her mother during the process of birth, then we give them an antibiotic for the first ear or sinus infection (which would go away untreated) and wipe them all out. The gut has an enormous number of nerve endings and some believe that the food we eat, combined with the bacteria, communicates with these nerve endings and affects our health. The gut is responsible for most of our immune system, something like 2/3, don't quote me, and produces many of the neurotransmitters. But these bacteria are not patentable and are not making the drug companies any money, so why worry about them, right?
Ron