The study, published in the American Journal of Gastroenterology, is the first to scientifically evaluate St. John's wort as a treatment for IBS. The herb is used to treat depression. Since antidepressants are commonly used to treat IBS, researchers wanted to see if St. John's wort might also treat IBS.
"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 researcher Yuri Saito, MD, MPH, of the Mayo Clinic in Rochester, Minn. "Unfortunately, our study showed that St. John's wort was not successful in helping IBS patients."
IBS affects up to 20% of adults in the U.S., mostly women, according to the National Institutes of Health. It's a common disorder that causes symptoms such as cramping, abdominal pain, bloating, gas, diarrhea, and constipation.
"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," says Saito in a news release.
In the study, 70 people with irritable bowl syndrome (86% women) were randomly divided into two groups. One group was treated with 450 milligrams of St. John's wort twice a day; the other group received a placebo treatment.
But the study showed that a greater improvement in IBS symptoms was seen in the placebo group than in the group treated with St. John's wort.