Probiotics as medical therapies

Mark Miller's primary criticism of my research letter1 is that the term “underuse” is misleading and indicates a “biased notion that is inappropriate as a starting point for this type of research.” First, the term accurately reflects the fundamental outcome of the research: only 32% of the physicians who responded to the survey recommend probiotics to patients when prescribing antibiotics and only 15% reported that they do so always or often. Second, given the reported benefits of probiotics, the rationale for my study was that probiotics should be coprescribed with antibiotics. My premise that probiotics have potential benefits is the same basic premise Miller uses in describing his research into “the effectiveness of Lactobacillus rhamnosus GG in preventing Clostridium difficile- associated diarrhea.” Finally, Miller's suggestion that my title should have been “Attitudes of family physicians about probiotic use” indicates a lack of understanding. The purpose of the research was to determine the rates at which physicians recommend probiotic use and their rationales for recommending or not recommending the use of probiotics. The attitudinal finding that physicians want more research and information on probiotics was a complementary, but secondary, result.

Miller is correct that pseudomembranous colitis is not caused by antibiotic-related diarrhea. The word “this” in the second sentence of my research letter should have referred to the destruction of intestinal flora, not to antibiotic-related diarrhea.

Miller says my claim that probiotics beneficially affect humans by altering their intestinal microbial balance is unsubstantiated. However, his argument is primarily based on problems related to the use of poor-quality probiotics, not on the effectiveness of high-quality probiotics. I wholeheartedly agree that “each of these agents must be tested and assessed in proper trials.”

I maintain that the benefits of probiotics for the conditions I described are well documented and should not be negated or ignored because we have not yet proven the effectiveness of all probiotics.