Hawrelak JA, et al. Effects of two natural medicine formulations on irritable bowel syndrome symptoms: a pilot study. J Altern Complement Med. 2010 Oct;16(10):1065-71.
This two arm, open label, uncontrolled pilot study enrolled 31 patients who fulfilled the Rome II criteria for irritable bowel syndrome (IBS). The patients were classified as either having diarrhea-prominent or alternating bowel habit IBS (n=21), or constipation predominant IBS (n=10). A formula (DA-IBS) containing dried, powdered bilberry fruit, slippery elm bark, agrimony, and cinnamon was given to the patients with diarrhea-prominent or alternating bowel habit IBS. Patients with constipation predominant IBS were given a formula (C-IBS) containing dried, powdered slippery elm bark, lactulose, oat bran, and licorice root. The group receiving DA-IBS experienced a small, but significant increase in bowel movement frequency (p=0.027). Subjects in this group also experienced reductions in straining (p=0.004), abdominal pain (p=0.006), bloating (p<0.0001), flatulence (p=0.0001), and global IBS symptoms (p=0.002). Subjects who received C-IBS experienced an improvement in stool consistency (p<0.0001) and a 20% improvement in bowel movement frequency (p=0.016), as well as significant reductions in straining (p<0.0001), abdominal pain (p=0.032), bloating (p=0.034) and global IBS symptom severity (p=0.0005). The authors concluded that the DA-IBS formula mostly improved IBS symptoms in patients with diarrhea-prominent or alternative bowel habit IBS, but the C-IBS formula improved both bowel habits and IBS symptoms in patients with constipation-predominant IBS. They recommend that the C-IBS formula be further investigated as a potentially useful therapeutic formula for IBS. However, it is unclear if slippery elm alone has the same effects.