SAN DIEGO – With consumers buzzing about the advertised benefits of probiotics for a healthy gut, what’s a primary care physician to recommend?

At a meeting on primary care medicine sponsored by the Scripps Clinic, Dr. Walter J. Coyle emphasized that while probiotics may play a role in the treatment and management of certain gastroenterological conditions, "there are not a lot of well-done randomized, placebo-controlled trials of these drugs. Most GI physicians use probiotics regularly, but our understanding of how these products work and interact with our immune systems and gut lining is still in its infancy."

The majority of probiotics are gram-positive lactic acid producers such as Bifidobacterium and Lactobacillus species, "which survive in transit through the stomach and duodenum," said Dr. Coyle, a gastroenterologist who directs the Scripps Clinic Gastroenterology Fellowship Program. Others include nonpathogenic streptococci, enterococci, Escherichia coli Nissle 1917, and Saccharomyces boulardii (yeast).

Dr. Coyle discussed the potential benefits of several probiotics on the market:

– VSL #3. This product contains four lactobacilli organisms (L. plantarum, casei, acidopholus, and delbrueckii), three bifidobacteria organisms (B. infantis, breve, and longum), and one streptococcus organism (Streptococcus salivarius subsp. thermophilus). "It’s fairly expensive and has to be kept refrigerated," Dr. Coyle said. "Randomized placebo-controlled trials have shown it’s very good for pouchitis." A more recent study of its use in ulcerative colitis patients found that it was superior to placebo in mild to moderate activity (Am. J. Gastroenterol. 2010; 105:2218-27). "It’s not one of my first-line therapies for inflammatory bowel disease, but it is out there as an alternative," he said.

– Digestive Advantage for IBS. This product contains Ganeden BC³⁰, a patented bacteria strain of Bacillus coagulans, erythritol, cellulose, and other minor ingredients. One small, randomized, double-blind, placebo-controlled trial found it to be an effective treatment of abdominal pain and bloating in patients with irritable bowel syndrome (Postgrad. Med. 2009;121 [doi: 10.3810/pgm.2009.03.1984]). "I’ll try it if the patients fail to have symptom improvement with other therapies, but there are no really well done randomized, placebo-controlled trials, which is the problem with most probiotics," Dr. Coyle said.

– Align. This product contains a patented strain of Bifidobacterium infantis 35624. In two large trials, it demonstrated decreased symptoms in IBS patients, "mostly in bloating and a little bit on flatulence," he said. This probiotic was also shown in trials to decrease the mucosal levels of IL-6, a known inflammatory cytokine. (See Gastroenterol. 2005;128:541-51 and Am. J. Gastroenterol. 2006;101:1581-90.) "I often try Align for my irritable bowel patients," he said.

– Florastor (Saccharomyces boulardii). This product has been shown to help prevent recurrent Clostridium difficile infections and to decrease diarrhea associated with antibiotic use. The dosing in one randomized, placebo-controlled study (JAMA 1994;271:1913-8) was two tablets twice per day, "which is expensive," Dr. Coyle said. "I typically recommend one tablet twice a day. However, for those patients who have had multiple recurrences of C. difficile, I do use the higher dose of two tablets twice per day."

– Actimel. This yogurt-type drink contains the patented yogurt culture known as Lactobacillus casei Immunitas. In a 2007 randomized, placebo-controlled trial of 135 hospitalized patients on antibiotics, those who received an Actimel-like product were significantly less likely to develop hospital-acquired diarrhea, compared with those who received placebo (12% vs. 34%, respectively). A similar association was seen in the prevention of hospital-acquired C. difficile (BMJ 2007;335:80 [doi: 10.1136/bmj.39231.599815.55]).

In this trial, "you only needed to treat five patients to prevent one case of hospital-acquired diarrhea, and you only needed to treat six patients to prevent one case of hospital-acquired C. difficile," Dr. Coyle said. "Why are we not doing this in the hospital?"

– Activia. This yogurt product contains Bifidus regularis and Bifidobacterium animus, and has been shown in scientific studies to increase transit time in women and in older adults. "If you like the taste of Activia, take it," he commented. "I don’t think I’d take it for making your gut healthier. It may, but we don’t have the data. It does help in patients who are often constipated. I’m fine with that, but I’m not sure I would classify it as a medical food."

– Culturelle. This product contains Lactobacillus rhamnosus GG and has been shown in scientific studies to be superior to placebo for diarrheal illnesses. "It’s proven to survive transit through the stomach and small intestine, and binds to human colonocytes," Dr. Coyle said. "It’s a reasonable choice for diarrhea patients and it’s been around for a long time."

He noted that current studies of prebiotics – ingested substances that selectively stimulate the proliferation or activity of desirable bacterial populations present in the host intestinal tract – have the potential for significant impact in the field of gastroenterology. "Is it possible to design a food, sugar, protein, or fat that would alter your gut flora to promote weight loss? That concept is exciting," he said. "I think you’re going to see a lot coming down the line on this."

Dr. Coyle said that he had no relevant financial disclosures.

Understanding of Probiotics 'Still in Its Infancy'