Well I havent read any of the big well written Colloidal Silver books which have alot more info than can be found normally. I have read that theres NO evidence of this happening from all the Net research I've done and thats quite a bit. It takes alot for the Colloidal Silver to enter the Flora area and you would need around 200ml and force it down with 500ml of water. This incidentally is the correct way to take Acidophilus or Probiotics. If you are worried about this then just take a nice supplement of one or the other of what I just mentioned. I know people who've take silver in nice small dosages and never having any supplement and have a weak diet also. Go for it you wont look back!