It was unclear how many studies were included in the review.
Ginger: the included studies were not of patients with IBS.
Aloe: the included study was not of patients with IBS.
Peppermint oil: one study was excluded on the grounds that the predominantly male Taiwanese patients were not representative of patients seen by most clinicians, while another was excluded because of methodological differences (no further information provided). Four double-blind placebo-controlled trials were combined in a meta-analysis (n=153). Peppermint oil resulted in greater improvement than placebo (OR 2.70, 95% CI: 1.56, 4.76). There was statistically significant heterogeneity (P<0.001).
Probiotics: three double-blind RCTs provided contradictory information on the effectiveness of probiotics, with two of the studies failing to show any benefit.
Exclusion diets: the number of included studies was unclear. The authors stated that positive responses to elimination ranged from 15 to 71%.
Cromolyn sodium: one RCT was not of IBS patients; one double blind-placebo-controlled RCT found significantly greater symptom reduction in the intervention group; two other included studies did not meet the pre-specified inclusion criteria.
Bulking agents: two reviews were reported. The authors stated that the efficacy of the intervention has not been clearly established.
Pancreatic enzymes: a single poor-quality trial showed limited evidence for the efficacy of this intervention.
Lactose restricted diet: four included uncontrolled studies did not meet the pre-specified inclusion criteria, while one double-blind crossover RCT (n=12) did not find any evidence for the effectiveness of lactase supplement.
Hypnotherapy: one included study was uncontrolled and did not meet the pre-specified inclusion criteria; two poor-quality RCTs (n=42) found some evidence for the effectiveness of hypnotherapy over the control group.
Psychotherapy: four poor-quality RCTs (n=257) found some evidence for the effectiveness of psychotherapy in comparison with the control group.
Behaviour therapy: four poor-quality RCTs (n=160) showed some evidence for the effectiveness of behaviour therapy over the control group.
Multicomponent therapy: five poor-quality RCTs (n=322) showed some evidence for the effectiveness of multicomponent therapy in comparison with the control group.
A meta-analysis of four studies of psychological therapy was reported. However, it was unclear why these studies were chosen for inclusion in a meta-analysis