You know, I used to think that was true, but now I'm not so sure (not that I'm any authority on this, either!) But let me tell you about an observation I had. I first took Humaworm in April 2007 for a vicious skin yeast infection that had taken over my body. It really gave the knock out punch to that yeast infection and totally cured me of it. Then, about three days after I went off of Humaworm, I developed a very thin layer of yeast all over my groin area, where my original skin yeast infection had started. The colonies were so young and unestablished, though, that they were easily killed off with a topical antifungal. I thought at the time that the yeast had reappered a few days after going off of Humaworm because Humaworm had killed off all of my good bacteria, which had allowed it to regrow until I could get the good bacteria re-established through probiotics.
Then, I took my second round of Humaworm in October 2007. After I finished my second round, I was watching and waiting to see if the yeast would come back, the same as it had before. In fact, I fully expected it to come back. But surprisingly, after I went off of the second round of Humaworm, it didn't. It was nowhere to be found. It seemed to me at the time that Humaworm must not kill off all good bacteria, because otherwise, the same thing should have happened to me again. While I don't know the answer to your question, I wanted to make this observation.