Dr. Tobias GutMeister Ultimate Prebiotics includes PreforPro, a cocktail of prebiotic type called bacteriophages. Each bacteriophage is specific to a certain (unhealthy) strain of bacteria from which it is also harvested. Once introduced into the body the bacteriophage targets the same strain. Specifically, the unhealthy e.coli strains.
As the unhealthy bacteria is destroyed by a bacteriophage it creates a food source for healthy bacteria, which is how the term "prebiotic" is justified.
A typical prebiotic feeds both good and bad bacteria. This would be one of the aspects to make PreforPro such a beneficial and unique approach. No side effects are known for PreforPro.
It is important to take the product daily so as to keep the PreforPro active in the intestinal tract.
The PreforPro material does not exist for any long period of time in the body which is the reason to keep taking it if desired.
Once the product is discontinued it may be possible for unhealthy strains to increase again depending on the individual.