Frangula, commonly known as buckthorn (specifically Frangula alnus or Rhamnus frangula), has a long history of use in traditional herbal medicine, primarily as a laxative due to its anthraquinone content. Traditional European herbalists used frangula bark for constipation and digestive disturbances. Its use for colitis, however, is primarily based on the notion that relieving constipation and promoting bowel movements could theoretically support gut health in people with colitis. There is no robust scientific evidence from clinical trials to support its efficacy or safety specifically for inflammatory bowel diseases like ulcerative colitis or Crohn’s disease. In fact, stimulant laxatives such as frangula are generally cautioned against in active inflammatory bowel diseases, as they may exacerbate symptoms like diarrhea and abdominal cramping, and potentially irritate the bowel lining. Modern phytotherapy references may mention frangula in the context of general digestive health, but reputable guidelines do not endorse it for colitis treatment. Thus, its use for colitis is justified mainly by tradition, not by clinical evidence, and the supporting evidence is very weak.