According to findings in the American Journal of Gastroenterology, extracts from the little yellow flower did not improve symptoms associated with IBS, such as stomach pain, diarrhoea, constipation and bloating.
Extracts of the plant Hypericum perforatum, commonly known as St. John's wort, have already been shown to help in patients with minor depression but in patients with more severe depression, the efficacy has been disputed.
According to the Mayo Clinic researchers, it is common for IBS sufferers to use anti-depressants, despite no study reporting the efficacy of St. John's wort for this condition.
“Our study investigated if herbal antidepressants such as St. John's wort could benefit irritable bowel disease patients,” explained Yuri Saito, 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 [for improving the symptoms of] IBS.”
The precise numbers of IBS suffers in the US are not known, as many people with mild symptoms do not consult a physician, but it is believed to be between 15 and 30 million.
The long-term condition, from which more women suffer than men, involves abdominal discomfort accompanied by diarrhoea or constipation. Although it is not life threatening and dose not lead to other, more serious health conditions, IBS is untreatable. At present, intervention involves management of symptoms.
The researchers recruited 70 people with IBS with an average age of 42 and randomly assigned them to receive a daily dose of St. John's wort or placebo for three months.
No improvements in measures of stomach pain, diarrhoea, constipation and bloating were recorded in the herbal group, said the researchers.
“Because people tend to struggle with IBS for several years, patients are really looking for inexpensive, over-the-counter [options], such as St. John's wort,” said Dr. Saito. “Unfortunately, our study showed that St. John's wort was not successful in helping IBS patients.”
Source: The American Journal of Gastroenterology
Published online ahead of print, doi:10.1038/ajg.2009.577
“A Randomized, Double-Blind, Placebo-Controlled Trial of St John's Wort for Treating Irritable Bowel Syndrome”
Authors: Y.A. Saito, E. Rey, A.E Almazar-Elder, W.S. Harmsen, A.R. Zinsmeister, G.R. Locke, N.J. Talley