ROCHESTER, Minn. -- A Mayo Clinic research study published in the January issue of the American Journal of Gastroenterology finds that St. John's wort is not an effective treatment for irritable bowel syndrome (IBS).

While antidepressants are frequently used to treat IBS, to date, no study has examined the success of using the herbal supplement St. John's wort in treating IBS.

"Our study investigated if herbal antidepressants such as St. John's wort could benefit irritable bowel disease patients," says Yuri Saito, M.D., M.P.H., gastroenterologist and lead physician scientist on the study. "Several of the chemical neurotransmitters that are in the brain are also in the colon. Therefore, it's been thought that antidepressants may affect sensation in the colon in a similar way to how they affect sensation in the brain. Our goal was to evaluate the usefulness of St John's wort in treating IBS."

In this placebo-controlled trial, 70 participants with IBS were randomized where half the patients received St. John's wort and the other half received a placebo for three months. In all, 86 percent of the participants were women, and the median age was 42 years. After three months of observing symptoms such as stomach pain, diarrhea, constipation and bloating, Mayo researchers found that the placebo group had a better response than the group taking the herbal supplement, St. John's wort.

"Because people tend to struggle with IBS for several years, patients are really looking for inexpensive, over-the-counter treatments such as St. John's wort," says Dr. Saito. "Unfortunately, our study showed that St. John's wort was not successful in helping IBS patients."

St. John's wort is an herbal supplement derived from the St. John's wort plant. It has been shown to be helpful in several medical conditions such as depression as well as other pain syndromes. Research has shown it to be as effective as conventional, prescription anti-depressants in treating mild to moderate depression.

"The challenge with IBS is that there is no cure, no one treatment tends to be wholly effective and some treatments come with significant side effects," explains Dr. Saito. "However, well-designed studies of herbal supplements are important so that physicians and patients can make informed decisions about which supplements to recommend or try. Studies of alternative treatments are generally lacking and patients are forced to use a "trial and error" approach to over-the-counter treatments for their IBS."

IBS is a common disorder that affects the colon and commonly causes cramping, abdominal pain, bloating, gas, diarrhea and constipation. Approximately 58 million people struggle with IBS, mostly women.

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Each year, Mayo Clinic physicians treat thousands of people with IBS. Read more information on treatment for irritable bowel syndrome at Mayo Clinic.

Mayo Clinic's Division of Gastroenterology and Hepatology has been ranked #1 in the U.S. News & World Report Honor Roll of Top Hospitals since the rankings began 20 years ago.

Other members of the Mayo Clinic research team included Enrique Rey, M.D.; Ann Almazar-Elder; W. Scott Harmsen; Alan Zinsmeister, Ph.D.; G. Richard Locke , M.D.; and Nicholas Talley, M.D., Ph.D.

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