Probiotic use may reduce diarrhea risk

Giving patients live bacteria may be as therapeutic as prescribing drugs to kill such organisms, according to several papers published last month.

"It's not true anymore that the only good bacteria are dead bacteria," said Patricia Raymond, MD, a gastroenterologist and associate professor at Eastern Virginia Medical School in Norfolk.

A literature review in the July issue of Chest found that probiotics could prevent episodes of antibiotic-associated diarrhea in the hospital setting, and data from a randomized clinical trial published in the July 14 British Medical Journal reached a similar conclusion.

The BMJ project randomized 135 hospitalized elderly patients taking antibiotics to receive either DanActive -- a yogurt drink containing Lactobacillus casei, Lactobacillus bulgaricus and Streptococcus thermophilus -- or a sterile milkshake twice a day and for one week after discontinuing these drugs. Those who received the probiotics reduced their risk of diarrhea related to these medications by 21.6% and diarrhea caused by Clostridium difficile by 17%.

"We suggest that older patients who are taking antibiotics will reduce their risk of getting diarrhea if they take this probiotic drink," said Dr. Mary Hickson, a research dietician at Hammersmith Hospital in London, England.

These papers are part of an increasing body of literature supporting the use of probiotics in the health care setting, something that is increasingly common in Europe. On this side of the pond, probiotics are starting to be used as part of the treatment regimens for a wide array of gastrointestinal ills. Those researching this issue say this approach is a low-risk, low-cost intervention.

"Most people tolerate probiotics quite well, and they're not that expensive," said Lynne M. McFarland, PhD, who wrote an editorial accompanying the BMJ paper and is a research health specialist at VA Puget Sound Health Care System in Seattle. "And antibiotic-related diarrhea means longer hospitalizations and more illnesses. If you get C. diff., the risk of mortality is higher. It's not something you want to get." Dr. McFarland is also the co-author of the book The Power of Probiotics.

More study needed

But while these publications are promising, researchers and other experts expressed caution, because other studies have had mixed results. Most consider the British study to be too small to be definitive, with limited application outside the hospital setting or to those who are healthier and younger.

Patient characteristics, such as reasons for hospitalization and the particular antibiotics prescribed, were not included. In addition, probiotics are not completely risk-free, particularly for those with immune-system issues or some heart conditions who were excluded from the trial for this reason.

"One would love to get a simple, safe, preventive measure for antibiotic-related diarrhea. But although this is an interesting study, questions remain," said William Schaffner, MD, chair of the Dept. of Preventive Medicine at Vanderbilt University School of Medicine in Nashville, Tenn. "I'm left more curious than convinced, but I'm glad people are looking at this."

It's also become increasingly clear that not all of the beneficial bacterial strains have the same effect and that, much like antibiotics, different strains most likely will suit varying purposes.

"We just don't know if we are giving the right species," said Dr. Warren Isakow, lead author on the review in Chest and assistant professor in pulmonary and critical care at Washington University School of Medicine in St. Louis. "Maybe different species prefer to live in different environments in the body."

There also are questions about the quality of the increasing number of probiotic preparations available on the market. Most of these products are regulated as supplements and are not tested routinely by the Food and Drug Administration.

A report issued in December 2006 by ConsumerLab.com, an independent laboratory that tests nutritional products, found that only eight of 13 of the probiotic products tested met the minimum requirements of at least 1 billion microorganisms per dose and matched what their labels claimed.

"It's been really challenging for me to know what to recommend for my patients," said Charlene Prather, MD, MPH, associate professor of internal medicine at Saint Louis University School of Medicine, who has been incorporating probiotics into her practice. "There are lots of different types, and you don't ever really know what you're getting, with a few exceptions."

More studies are being planned, and many experts view them as desperately needed.

The review in Chest called for the National Institutes of Health to sponsor multicenter trials, but many experts say the fact that these are usually considered supplements most likely will interfere with getting the larger studies funded and completed. They are not required by regulatory agencies, and probiotics are far less expensive than many prescription drugs, meaning that this kind of research may not be financially viable.

"We need large, multicenter, randomized clinical trials looking at specific questions," Dr. Isakow said. "But these studies are probably never going to get done."