Table 2.

Clinical trials on Herbal medicines and supplements for irritable bowel syndrome

Intervention	Study design	Sample size	Outcome	Ref.
Peppermint oil	Randomized, double-blind, placebo-controlled study	99	Peppermint oil (Colpermin®) group showed significant symptom improvement (P < 0.05) compared to placebo group after 1 mo	[104]
Peppermint oil	Randomized, placebo-controlled study	18	Peppermint oil significantly reduced GI symptoms (P < 0.01) after 3 wk compared to placebo	[106]
Peppermint oil	Randomized, double-blind. Placebo-controlled study	57	Total IBS severity score was significantly decreased after 4 wk of treatment (P < 0.009) and after 2 mo (P < 0.01) in the peppermint oil group compared to placebo	[108]
Peppermint oil	Randomized, double-blind, placebo-controlled study	90	Significant reduction in IBS symptoms, no abdominal pain in more patients in the peppermint oil group compared to placebo (P < 0.001), less severe abdominal pain in peppermint oil group (P < 0.05) in peppermint oil group after 2 mo	[109]
Peppermint oil	Randomized, double-blind, placebo-controlled study	65	Significant reduction in abdominal pain in peppermint oil group compared to placebo group (P < 0.001), but pain score increased 2 wk after completion of trial	[110]
Artichoke leaf	Post-marketing surveillance	279	Significant reduction (P < 0.05) in overall IBS symptoms after 6 wk of treatment	[113]
Artichoke leaf	Post-marketing surveillance in IBS with concomitant dyspepsia	209	Significant reduction in Nepean Dyspepsia Index after 2 mo (P < 0.001) and normalization of bowel pattern (P < 0.001)	[114]
Turmeric	Partially blinded, randomized, two-dose pilot study	207	Reduction in IBS prevalence in both treatment groups (1 or 2 tablets) compared to baseline (P < 0.001) after 2 mo intervention, no significant differences between groups	[116]
Curcuma and fumitory	Randomized, double-blind, placebo-controlled study	106	No significant differences between curcuma, fumitory, and placebo groups in abdominal pain (P = 0.81) and distension (P = 0.48) after 3 mo	[117]
STW5	Randomized, double-blind, placebo-controlled study in patients with dyspepsia	137	Significant decrease in gastrointestinal symptom score between STW5 and placebo (P < 0.001)	[118]
STW5	Randomized, double-blind, placebo-controlled multicenter study in patients with functional dyspepsia	315	Significant decrease in gastrointestinal symptom score between STW5 and placebo (P < 0.05) after 2 mo intervention	[119]
STW5	Randomized, double-blind, placebo-controlled multicenter study	203	Significant reduction in abdominal pain scores for STW5 (P = 0.009) and STW5-II (P = 0.005) and IBS-SSS (P = 0.001 for STW5 and P = 0.0003 for STW5-II) compared to placebo after 4 wk intervention	[120]
Padma Lax	Randomized, double-blind, placebo-controlled pilot study	61	Significant improvement in global IBS symptom scores compared to placebo (P < 0.05) following 3 mo intervention	[123]
TCM	Randomized, double-blind, placebo-controlled study	119	No significant improvements in IBS global symptom score between TCM and placebo group at week 8 (P = 0.38) and week 16 (P = 0.62)	[129]

IBS: Irritable bowel syndrome; TCM: Traditional chinese medicine; SSS: Symptom severity scale.