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Peppermint Oil, Fiber and Antispasmodic Drugs for IBS

Posted by medconsumers on January 1, 2009

Three inexpensive treatments work well for many people with irritable bowel syndrome, according to a new review published in the British Medical Journal. While peppermint oil, fiber and antispasmodic drugs have long been known to be helpful, uncertainties surround the supporting evidence. After evaluating 30 years of published research, the reviewers verified the effectiveness of these three treatments in comparison to placebo and found that peppermint oil may provide the strongest benefit.

These findings are of special interest due to the serious harms caused by two widely advertised prescription drugs for irritable bowel syndrome—Lotronex (ischemic colitis, transfusions, surgery, death) and Zelnorm (heart attacks, strokes).

The Fiber Trials
The symptoms of irritable bowel syndrome can be chronic and varied, including diarrhea, bloating, constipation and abdominal pain. And the condition is difficult to treat. Starting with the old, stand-by—fiber—the international review team led by Alexander C. Ford, McMaster University, Hamilton, Ontario, Canada, found 12 trials that explored this treatment. Virtually all those that involved the insoluble fiber in wheat bran found that it was no better at easing symptoms than a low-fiber diet or placebo.

Soluble fiber is best, but the reviewers were careful to note that the beneficial effects seemed to be limited to ispaghula husk, also known as psyllium, which contains a high level of soluble dietary fiber. (This is the chief ingredient in many commonly used laxatives, such as Metamucil® and Serutan®.) Based on the six soluble fiber trials in this review, the reviewers estimated how many people experienced relief. For every six people on a diet high in ispaghula husk, one experienced symptom relief. Adverse effects were not mentioned by the authors of most of the 12 trials.

Peppermint Oil Trials
Peppermint oil was better than placebo at alleviating symptoms, though the trials did not use the same doses. (They ranged from 200 mg to 225 mg capsules of peppermint oil, taken two or three times daily.) While peppermint oil was the most effective of the three treatments, it had the least amount of supporting research. There were only four trials with 392 participants, altogether. Efficacy was high, though. For every two people who took peppermint oil, one experienced symptom relief. Adverse effects occurred in five people taking peppermint oil, compared to none for those taking placebo. The trial authors, however, did not elaborate on the nature of the adverse effects.

Anti-Spasmodic Trials
Antispasmodic drugs are generally seen as the first-line treatment, especially when pain and bloating are the predominant symptoms. The highest number of trials, 22 in all, compared antispasmodic drugs with placebo in 1,778 participants, altogether. Most followed participants for less than four months. Adverse effects were described as, “significantly more frequent in those taking antispasmodic drugs than in people taking placebo, but none was serious.” For every three or four people who took an antispasmodic drug, one experienced symptom relief. Of the five different antispasmodic drugs studied, only one drug, hyoscine, showed consistent evidence of efficacy. It is an inexpensive prescription drug that is available generically. This review of trials was funded by the American College of Gastroenterology.

Maryann Napoli, Center for Medical Consumers© January 2009

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