Authors searched for studies that evaluated the effectiveness of traditional herbs including Chinese, Tibetan and Indian herbal medicines and found 75 different randomised trials. The trials varied in quality, and investigated a wide range of different preparations. Most of the trials had been conducted in China and published in Chinese.
"Many of the trials were small, so it is premature to recommend herbal medicines for routine use in IBS, but there is evidence that some of the medicines did improve the global symptoms of IBS," says lead Review Author Prof Jianping Liu, who works both at the Evidence-based Chinese Medicine Centre for Clinical Research and Evaluation at Beijing University of Chinese Medicine, and at the National Research Centre in Complementary and Alternative Medicine (NAFKAM), University of Tromso, Norway.
Medicines that showed promise included Chinese herbal formulation and individualised herbal formulation; STW 5; SW 5_ii; as well as Tibetan herbal formula Padma Lax. The Chinese herbal medicine Tongxie Yaofang showed a statistically significant effect on global symptoms, as did the Indian Ayurvedic formula of two herbs.
Six small trials reported that combining conventional and herbal medicines produced greater benefits than using conventional therapies alone, but the Authors believe that larger trials are needed to confirm this finding.
"There is a great need for further rigorously conducted trials that look to see whether it is possible to replicate these positive effects," says Prof Liu.
One of the problems with comparing the results of different trials is the wide range of formulas used, and the imprecision with which different medicines are prepared. "For these trials to be useful they must also improve the description of the herbal medicines being tested," adds Prof Liu.
Notes for editors
1. Review Paper: Liu JP, Yang M, Liu YX, Wei ML, Grimsgaard S. Herbal medicines for treatment of irritable bowel syndrome. The Cochrane Database of Systematic Reviews 2006, Issue 1. Art. No.: CD004116.pub2. DOI: 10.1002/14651858.CD004116.pub2.
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