- Standard and individualized Chinese herbal formulations including "STW 5" and "STW 5-11"
- A Tibetan herbal formula called "Padma Lax"
- An Indian formula of two unnamed herbs used in Ayurveda, a traditional Indian health system
However, the review doesn't endorse or recommend any herbal medicines for irritable bowel syndrome, since many of the studies weren't of top-notch quality.
The report appears in The Cochrane Library, a health care research journal. The scientists included Jianping Liu, MD, PhD.
Liu works at Beijing University of Chinese Medicine's Evidence-based Chinese Medicine Centre for Clinical Research and Evaluation. He is also on staff at the National Research Centre in Complementary and Alternative Medicine at Norway's University of Tromso.
Helpful or Not?
The studies, which were mainly done in China, had a combined total of nearly 8,000 patients with IBS.
"Some herbal medicines may improve the symptoms of irritable bowel syndrome," the researchers write.
For instance, IBS patients in nine studies either got herbal and conventional medicines or conventional medicines alone. Those who got herbal and conventional medicines reported greater improvement of their IBS symptoms, the researchers note.
None of the studies reported serious side effects from any of the herbal medicines. But the researchers note that that doesn't mean that the medicines are safe for everyone.
Liu's team urges "caution" in considering positive findings from studies with poor design, small numbers of patients, and unconfirmed results.
The researchers' main criticisms were:
- Most studies were of low quality.
- Various formulas were used.
- Many studies didn't check long-term results.
For instance, some studies compared herbal medicines with conventional medicines, not all of which are proven to help irritable bowel syndrome. In other trials, herbal medicines were compared with placebos, which don't contain any conventional or herbal medicine.
Also, herbal medicines were often tailored to each patient, a typical practice in traditional Chinese medicine. Using similar formulas would have made comparisons easier, note Liu and colleagues.
"There is a great need for further rigorously conducted trials that look to see whether it is possible to replicate these positive effects," Liu says in a news release.
"For these trials to be useful, they must also improve the description of the herbal medicines being tested," he says.
The researchers' bottom line: "Some herbal medicines deserve further examination in high-quality trials," they write. Meanwhile, they call it "premature to recommend herbal medicines for routine use in irritable bowel syndrome."