Rhus coriaria (commonly known as sumac) has a long history of use in traditional medicine, particularly in the Middle East and Mediterranean regions. In these traditions, sumac has been employed for a variety of gastrointestinal issues, including indigestion, diarrhea, and other digestive complaints. Its use in supporting or treating Irritable Bowel Syndrome (IBS), however, is based more on its traditional application for general gut health and its purported anti-inflammatory and astringent properties than on targeted clinical trials specific to IBS.

There is limited scientific research directly assessing the efficacy of Rhus coriaria for IBS. A few in vitro and animal studies have suggested that sumac possesses antimicrobial, antioxidant, and anti-inflammatory effects, which could theoretically benefit gastrointestinal health. For instance, its polyphenolic compounds may help modulate gut inflammation, and its astringent properties could reduce diarrhea. However, there are no robust human clinical trials specifically examining sumac’s effect on IBS symptoms such as abdominal pain, bloating, or altered bowel habits.

In summary, while the traditional use of Rhus coriaria for general digestive health is well-documented, direct scientific validation for its use in IBS is lacking. The evidence for its use in IBS is therefore rated as low (2/5), reflecting reliance on traditional practices rather than strong clinical data.