March 30 (HealthDay News) -- Japanese herbal medicines may help people with gastrointestinal disorders -- such as constipation and indigestion -- that don't respond to conventional treatments, a new study suggests.

Many drugs used for these gastrointestinal "motility disorders" don't work or cause unwanted side effects, the researchers noted.

"Japanese herbal medicines have been used in East Asia for thousands of years. Our review of the world medical literature reveals that herbal medicines serve a valuable role in the management of patients with functional gastrointestinal disorders," lead researcher Hidekazu Suzuki, an associate professor at the Keio University School of Medicine, said in a news release.

The researchers analyzed data from studies that examined several different Japanese herbal medicines, including Rikkunshi-to and Dai-Kenchu-to. The results showed that Rikkunshi-to, which is prepared from eight herbs, helped reduce discomfort caused by functional dyspepsia (indigestion). Dai-Kenchu-to, a mixture of ginseng, ginger, and zanthoxylum fruit, was found to help constipation in children and patients with postoperative ileus, a disruption of normal bowel movements after surgery.

Another herbal medicine called hangeshashin-to reduced the severity and frequency of diarrhea caused by anti-cancer drugs.

The study appears in the current issue of Neurogastroenterology and Motility.

Herbal medicines made in Japan must meet standardized rules for quality and quantity of ingredients. The health benefits of this standardized approach need careful examination, particularly in the Western world, according to the researchers.

"There is a mandate to provide accurate data regarding the effectiveness of non-traditional therapy, not only to our patients but also to health-care providers who face the dilemma of recommending or opposing management strategies that incorporate herbal medicine," Suzuki said.

SOURCE: Wiley-Blackwell, news release, March 24, 2009