Often described as good bacteria, probiotics are live microorganisms that, when consumed, benefit the host. They are naturally occurring in dairy products in the United States and are common in OTC dietary supplements. Against a backdrop of widely reported rising antibiotic resistance, not to mention ballooning pharmaceutical prices, it is hard to argue against the case for these cost-effective agents as an alternative weapon against infectious diseases.
But how effective are probiotics, and do they stand up to the scientific rigors placed before other, more traditional pharmaceuticals so that pharmacists can confidently tout them?
The sweet spot for probiotics’ demonstrable efficacy, at least initially, might be in treating gastrointestinal (GI) diseases. According to Jessica L. Johnson, PharmD, BCPS, et al in this issue’s cover story, probiotics show potential value in smaller research studies in treating and preventing ulcerative colitis, irritable bowel syndrome (IBS), antibiotic-associated diarrhea, hepatic encephalopathy, and portal hypertension.
It makes sense that GI diseases are strong candidates for probiotic therapy, because it is there where probiotics originate and thrive. “Through the consolidation of selected scientific evidence,” Johnson et al conclude, “healthcare professionals can assist with selecting specific regimens for patients seeking to use probiotics as adjunct therapy for gastrointestinal diseases.”
Johnson et al concede the challenge facing pharmacists, however, looking to counsel patients attracted to these readily available, comparitively low-cost agents. Robust studies are needed, the authors say, to evaluate efficacy and safety in special populations or compare probiotic strains head-to-head. “Although probiotics are not currently FDA-approved as pharmacologic treatment,” the authors write, “scientific evidence thus far indicates probiotics play an integral role in improving patient outcomes in many GI diseases.”
Authors of an earlier article in U.S. Pharmacist concur. As reported in an April feature by Erin Dorval, PharmD, the limited and oftentimes inconclusive evidence of probiotics’ effectiveness in treating antibiotic-associated diarrhea, vulvovaginal candidiasis, and the common cold ties the hands of pharmacists making recommendations.
Doral concludes that sufficient data are lacking to warrant promoting probiotics therapy in all patients. At the same time, Doral acknowledges studies of some promising bacterial strains, calling for more standardized clinical research.
A Moving Target
Other researchers agree that proving probiotics’ efficacy is something of a moving target, particularly in treating IBS. In January, Rajilic-Stojanovic et al reported in the American Journal of Gastroenterology that establishing the links between IBS, microbiota, and diet is challenging because patients with this condition fall into a heterogeneous group with varying symptoms and foodstuffs that they might respond to. They also point out that the intestinal bacteria environment present in individual patients is highly complex, concluding, “It is clear that defining the correlations between IBS, microbiota, and diet is not an easy task.”
The value of probiotics might well extend beyond GI efficacies. In May, the journal International Forum of Allergy & Rhinology reported the microorganisms might help alleviate allergic rhinitis symptoms, based on results of a Vanderbilt University study examining 23 earlier clinical trials.
There, too, the researchers are careful to avoid hyperbole. Lead study author, Justin Turner, MD, PhD, concluded that there was a statistically significant improvement in both rhinitis- and nasal-specific quality of life in patients taking probiotics, but added, “The jury is still out,” also calling for more research.
Clearly, more rigorous work in gathering and synthesizing data is needed to substantiate probiotics’ promise. Given their many advantages, including easy access, it is probably well worth it.
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