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- In Defense of Probiotics
Regarding the letter ``Probiotic Lactobacilli Implicated in Liver Abscess'' published in ASM News, February 2000, p. 59, Michael Teuber's negative comments should be taken into context. Respectable scientists and clinicians working in the field of probiotics are very cognizant of the potential for any bacteria to cause infection if they are allowed to enter the bloodstream of patients, such as those who are immunosuppressed or have a complicated illness such as diabetes. I have referenced that this rare event can indeed happen (Clin. Microbiol. Rev. 3:335-344, 1990). Gerald Tannock, a well-known researcher on probiotics and the intestinal flora, covered this very topic in a recent article which featured probiotics, including our own work (Lancet 354:1884, 1999). However, Dr. Teuber needs to be reminded of the bigger picture, and he should place the isolated case reports in perspective.
Lactic acid bacteria are generally regarded as safe (GRAS) and therefore are denoted as such by international agencies. In a recent review, it was found that oral administration of lactic acid bacteria to 7,526 subjects studied between 1961 and 1998 did not result in any side effects (Naidu et al., Crit. Rev. Food Sci. Nutr. 39:13-126, 1999). This is remarkable compared to antibiotic therapy, whose side effects are well known and can include death. Ironically, many of the problems being addressed by probiotics (e.g., certain diarrheas and urogenital infections) are caused by antibiotic use.
I would be the first to admit that too many unreliable so-called probiotic products are on the market, and Hamilton-Miller's recent paper (Pub. Health Nutr. 2:223-229, 1999) confirms what I and Dr. Sharon Hillier have stated previously. Indeed, this was one reason why I wrote a review (Appl. Environ. Microbiol. 65:3763-3766, 1999) to urge people to use a scientific basis to develop future products.
We don't need to beat the bushes to find people willing to criticize probiotic concepts. It has taken many years and many excellent studies to finally convince some scientists and clinicians that probiotics and other remedies which alter the host's microbial flora, can and should have a place in health maintenance and restoration and in disease control. The strain L. rhamnosus GG, cited by Teuber, has helped improve the well-being of many people, as shown in a number of well-designed trials.
The need to fund this type of research is critical and agencies on this continent have been very slow to do so, thus making it difficult to produce the volume of data accumulated on antibiotics or other pharmaceutical products. ``Deleterious observations'' are extremely rare, and while they should be noted, negative comments should not deflect from the critical issue. We need to find alternatives to current antibiotics, find ways to restore and maintain gastrointestinal, urogenital, and nasopharyngeal health, and explore natural rather than chemical means to provide some benefits to human and animal hosts. Probiotics will be an important part of this solution, and careful attention to their selection and administration will, I believe, provide far more benefits than harm.
Gregor Reid
The University of Western Ontario
The Lawson Research Institute
London, Ontario, Canada
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