Probiotic supplements may greatly lower the threat of an antibiotic-resistant "superbug" that has alarmed hospital leaders, according to Bastyr University research.
Researchers found that patients taking probiotics, or live bacteria, were 64 percent less likely to experience the effects of Clostridium difficile, an infectious bacterium that can cause severe diarrhea and life-threatening inflammation of the colon.
The analysis was published by the Cochrane Collaboration, a database highly regarded for its comprehensiveness. The low-cost, low-risk nature of probiotics, coupled with the unusually strong findings, could create an immediate impact on medical practice. The study (and an earlier version) has already received attention from the BBC, The New York Times, Nature.com and major aggregators of research news.
That's an encouraging sign for researchers led by Joshua Goldenberg, ND ('13), who graduated in June from Bastyr's Doctor of Naturopathic Medicine program.
"Naturopathic doctors have been prescribing probiotics for patients using antibiotics for a long time," says Dr. Goldenberg. "Now we have rigorous evidence behind it. We cut the risk down by two-thirds. There are very few medical interventions, conventional or naturopathic, that improve results by that much."
Restoring Gut Balance
Hospitals have struggled in recent years with the rise of C. difficile-associated diarrhea (CDAD). The strain most commonly affects older adults using antibiotics in hospitals and long-term care facilities. But rates have risen among younger individuals and other populations not typically considered high-risk, according to the Mayo Clinic.
"Each year, more than a half-million people get sick from C. difficile, and in recent years, C. difficile infections have become more frequent, severe and difficult to treat," the Mayo Clinic reports.
Swedish Medical Center in Seattle is reviewing its probiotics policies in response to recent research, including Bastyr's, says Dan Labriola, ND, medical director for naturopathic services at Swedish.
Per Vandvik, MD, a gastroenterologist in Norway, said the study helped convince him to prescribe probiotics along with antibiotics to reduce cases of CDAD. He hopes more care providers will recommend probiotics when they prescribe antibiotics.
"Most patients would want to take this treatment if they were well-informed about the benefits and absence of detectable harms," says Dr. Vandvik, a co-author of the study.
For many, it's old news that probiotics help restore the balance of bacteria in the intestinal tract. Sales of probiotic supplements and foods (such as yogurt, sauerkraut and other fermented foods) have risen sharply in recent years. (Read more on the benefits of probiotic foods.) They provide a balance to antibiotics, which fight disease but disrupt the intestinal balance.
"Using probiotics when taking antibiotics is sort of a quintessential naturopathic treatment," Dr. Goldenberg says. "You use conventional medicine when needed, but you add a naturopathic element to make it safer."
Weeding Out Bias
The Cochrane study analyzed data from 23 clinical trials with 4,213 total participants. It found that 2 percent of participants in the probiotic group experienced CDAD, compared to 5.5 percent in the placebo or no treatment control group.
As a meta-analysis, or study of other studies, the paper uses the Cochrane Collaboration's widely praised approach of searching for every possible examination of the topic. The work took three years, but Dr. Goldenberg believes the process is necessary to root out biases that can distort any single trial.
"We used to think the gold standard of research was the large randomized controlled trial," he says. "But researchers are finding that 50 percent of all studies, and even 25 percent of great studies, turn out to be wrong. They're affected by all sorts of biases. You can't see that unless you zoom out farther and combine a lot of randomized control trials together. Combining 10 or 20 clinical trials in a meta-analysis is really the platinum standard."
One common distortion is publication bias — the tendency that trials with positive results are more likely to be accepted by major journals. Cochrane reviews attempt to neutralize this problem by finding so-called gray literature — studies that have not been published in journals but appear at conferences, in dissertations or elsewhere. Seven of the trials Dr. Goldenberg's team investigated came from gray literature.
"Done properly, systematic reviews weed out those biases," says Jane Saxton, MLIS, Bastyr's director of library services and a co-author on the study.
Focus on Supplements
Surprisingly, the study found that C. difficile was still present in many patients, but diarrhea and other harmful effects were not. From the perspective of patient well-being, that's a positive result, Dr. Vandvik says. Dr. Goldenberg adds that there are rare cases in which probiotics have dangerous effects, such as in very young infants or patients with severe pancreatic illnesses. The study concluded probiotics are safe for "immunocompetent patients."
Dr. Goldenberg has collaborated on a previous Cochrane review and recently published a study of naturopathic attitudes toward evidence-based medicine. This summer he joined Northshore Family Practice in Kenmore, Washington, to focus on clinical practice.
The Cochrane study did not distinguish among types of probiotics — a task for further research. It was also restricted to probiotic supplements, not foods containing live cultures.
As a researcher, Dr. Goldenberg understands the precise focus on supplements. As a naturopathic doctor who ferments his own sauerkraut, kefir and kombucha, he finds it odd to focus on pills.
"Our results are restricted to patients who are prescribed antibiotics by their doctors to take probiotic pills at the same time," he says. "As a naturopathic doctor, it seems ridiculous to take pills when I can ferment kefir in my own kitchen. We evolved eating fermented foods that contain probiotics. We have this incredibly complex, beautiful flora of different organisms in our gut.
“So while I recommend probiotic pills for patients taking antibiotics, for general health I tell patients to eat the foods we evolved to consume — whole foods, some of them fermented."