About 99% of the bacteria in your gut are good. In fact, we can't get along without them. But roughly 1% of the bacteria in our GI tracts are pathogenic or "bad." They usually enter our systems by mouth, in the things we eat or drink.
Danger in Numbers
Having some pathogenic bacteria in your system is not unusual, nor particularly harmful, so long as their numbers are kept in check.
In animal studies, the prebiotic fiber MOS (mannan oligosaccharide) that is also found in ProBiotein, has been shown to increase blood lymphocyte levels. This helps support immunity and reduce dangerous bacteria, like salmonella, E. coli and clostridia – all common intestinal pathogens.
There is recent research that suggests our society's use of antibiotic soaps, our eagerness to treat even mild illnesses with antibiotic drugs and our general "over-cleanliness" may in fact be robbing us of some important bacteria in our systems.
So the relationship between human host and bacteria, and the balances of keeping so-called "bad" bacteria in proper proportion without eliminating them altogether, is a complicated riddle whose solution is still unfolding.