from my own experience, i can say that the nsd reduces bacterial concentrations in the gut across the board. right when i started the nsd, i tested positive for very high levels of the probiotic ("good") bacteria in my bowels. after several months on the strict nsd, a retest revealed that the probiotic bacteria levels dropped significantly, to almost zero. i was not experiementing with anything else that could reduce bacteria at the time (ie drugs etc) with the exception of the diet.
