Randomised Clinical Trial

Yoga vs a Low-FODMAP Diet in Patients With Irritable Bowel Syndrome

D. Schumann; J. Langhorst; G. Dobos; H. Cramer


Aliment Pharmacol Ther. 2018;47(2):203-211. 

In This Article


Summary of Evidence and Implications for Clinical Practice

This study may indicate beneficial effects from yoga to a low-FODMAP diet on gastrointestinal symptoms, health, anxiety, depression and stress for patients with IBS. Besides a significant difference in the subscale abdominal distension of the IBS-SSS at week 12 (P = .040) in favour of the FODMAP group, no between-group differences for participants' overall gastrointestinal symptoms could be shown. Nevertheless explorative within-group comparisons revealed statistically significant improvements in participants' overall gastrointestinal symptoms for both groups. Significant between-group differences were found in favour of the yoga group with regard to patients' levels of anxiety, body awareness and body responsiveness. The FODMAP diet had a nonsignificant tendency (P = .052) to induce remission more frequently than yoga, at 12 weeks, but this tendency was not seen at 24 weeks (P = 1.000). Only 1 randomised, controlled trial has studied the outcomes of a low-FODMAP diet for more than 6 weeks to date and more data on the long-term outcomes of a low-FODMAP diet are needed.[38,39] With regard to patient safety, yoga has occasionally been associated with serious adverse events in some case studies,[40] but most systematic reviews of yoga interventions, in varied patient populations, have failed to find such links.[13,14,16,19,41] No serious adverse events related to either yoga, or to patients' adoption of a low-FODMAP diet, were observed during the current study.

The value of a low-FODMAP diet is seen by some commentators as controversial. While the related carbohydrates are poorly absorbed in the small intestine, leading to increased intestinal osmolality and gas production due to their rapid fermentation and osmotic action, fructans and galacto-oligosaccharides serve as prebiotics.[42,43] It has been shown that low-FODMAP diets are effective in reducing bowel symptoms,[44] while they alter the colonic luminal microenvironment, possibly due to a lowered content of these prebiotics.[5,45] Unfortunately, no published data on the influence of hatha yoga on the gut microbiome exist to date. Since the latter is hypothesised to be involved in the aetiology of IBS and depression, the impact of a low-FODMAP diet and yoga on the gut microbiota warrants further research in this context.[46,47] Both of the current trial interventions require adequate supervision and are, thus, relatively cost-intensive. Adopting a low-FODMAP diet requires patients to engage in intensive meal planning; supervised closely by well-trained personnel. Such factors would offer considerable challenges if such diets were implemented in clinical practice. Moreover, the restrictions demanded by a low-FODMAP diet might lead to nutritional inadequacy and foster disordered eating.[43] In contrast, yoga could potentially enhance body awareness and responsiveness; lessening the occurrence of disordered eating attitudes.[34] A low-FODMAP-diet was found to improve patients' overall IBS symptoms in 4 of 4 studies reported elsewhere.[48] Most studies excluded IBS-C patients and as a result the low-FODMAP diet has been most extensively studied in IBS-D patients. The current trial found no statistically significant differences in an explorative subgroup analysis, comparing the effectiveness of a low-FODMAP diet in IBS-C and IBS-D patients. Elsewhere, Chumpitazi and colleagues have linked gut microbiome biomarkers to patients' clinical responses to a low-FODMAP diet, leading them to speculate that such diets may work differently for different patients.[49] With regard to the yoga intervention, it is important to note that the yoga classes delivered in the current trial were purpose-designed and adapted to patients' needs. The trial's yoga intervention encompassed philosophical elements, not usually included in conventional asana-based yoga classes; enhancing the psychological dimensions of the approach. Gut-directed hypnotherapy is another psychological therapy that has claimed to improve patients' IBS symptoms.[50] When such hypnotherapy was compared to the adoption of a low-FODMAP diet, in a randomised controlled study, neither intervention was found to be superior.[51] It should also be borne in mind that the current trial's yoga intervention was developed and delivered by an experienced yoga instructor, well-trained in the field, and was supported with videos to encourage patients to practice at home. These sessions were delivered twice a week; more often than the yoga interventions delivered in other studies. The latter were often less intensive, with either weekly yoga sessions or teaching delivered solely via videos for home-based practice.[19] Although the current trial's findings are limited, they may prove replicable if the above points are taken into consideration. Both hatha yoga and the adoption of a low-FODMAP diet may be feasible adjunctive therapies patients with IBS.

Strengths and Weaknesses

The strengths of this trial include its randomised controlled design, its ability to control for nonspecific therapy effects via the use of an active control group and its 'blinding' of outcome assessors. Its primary limitations are its monocentric design, its inability to 'blind' patients with regard to the allocated interventions and the subjective self-report nature of the outcome measures used to explore patients' gastrointestinal symptoms. The IBS-SSS may also fail to detect changes in patients with mild IBS, scoring lower than 175 points.[26]