Probiotic Relief from Irritable Bowel Syndrome (IBS)

Healthnotes Newswire (March 30, 2006)-A combination of lactobacilli and other probiotic bacteria has been found to ease the symptoms of irritable bowel syndrome (IBS), according to Alimentary Pharmacology and Therapeutics (2006;22:387-94). This new study is the largest and longest clinical trial of probiotics for IBS to date; results of previous studies have been mixed.

The double-blind, placebo-controlled trial included 103 people with established IBS. Each person was randomly assigned to receive either one probiotic capsule (containing a blend of Lactobacillus rhamnosus GG, L. rhamnosus LC705, Bifidobacterium breve Bb99, and Propionibacterium freudenreichii ssp. shermanii JS) or one placebo capsule each day for six months. Gastrointestinal symptoms were recorded. Total symptoms in the probiotic group were reduced by 42% compared with 6% in the placebo group.

Sometimes referred to as "spastic colon," IBS is a common gastrointestinal disorder, affecting 10 to 20% of the US population. It often causes significant discomfort, though it is not considered a serious health threat. IBS is considered a "functional disorder," because it refers to an altered bodily function rather than a specific disease. IBS is not related to inflammatory bowel diseases, such as Crohn's disease or ulcerative colitis. Typical symptoms include abdominal bloating and soreness, gas, and alternating diarrhea and constipation. The cause of IBS is unknown.

Probiotics are beneficial bacteria, many of which are normal inhabitants of the human intestinal tract. They are responsible for many functions, including manufacturing immune factors and preventing the growth of disease-causing bacteria in the gut. Lactobacilli and bifidobacteria are considered safe for both healthy and immunosuppressed people. Use of probiotic supplements has been associated with reduced incidences of cancer, gastroenteritis, and some allergic reactions. Several studies have shown that probiotic supplements effectively combat infectious diarrhea in children, antibiotic-associated diarrhea, and traveler's diarrhea. The specific blend of probiotics used in this study is not commercially available at this time.

It is not known how probiotics reduce the symptoms of IBS. Imbalances of the intestinal flora have been associated with IBS. Such imbalances could cause altered fermentation in the gut, leading to increased gas production. By restoring balance, probiotics could thus quell one symptom of IBS. Another theory is that overabundance of the wrong types of bacteria can trigger inflammation, leading to chronic bowel irritability and disordered regulation of bowel function by the brain. Further studies are warranted to learn which probiotic bacteria, or combinations of probiotic bacteria, work best for IBS, and why.