A team of scientists led by Jason Hawrelak from the University of Tasmania evaluated 18 different herbal preparations for IBS, and concluded that the evidence indicated that “peppermint essential oil is both efficacious and well-tolerated in the short-term management of IBS”.
There was also support for Aloe vera and asafetida, while a number of other herbal preparations show promise but the science is currently limited and needs to be replicated in more trials.
A helpful update
Commenting independently on the new systematic review and meta-analysis, Stefan Gafner, PhD, chief science officer of the American Botanical Council (ABC), told us that the review is “well done and provides a helpful update in an area where botanical ingredients traditionally are quite extensively used”.
Dr Gafner noted that a number of systematic reviews on herbal medicines for IBS, and systematic-reviews and meta-analysis for peppermint oil in treating IBS symptoms are available, but none since 2014.
“Since two studies were published in 2016, it appears to me that an update to include current literature is a worthy undertaking,” he noted. “And none of the papers reviewing botanical ingredients for IBS symptoms appear to be as thorough and as well done as this present publication.
“Doing a meta-analysis on two clinical studies, as in case with aloe and asafetida with about 130 patients each begs the question just how meaningful the results are. So, in absence of more data, there is definitely a future research opportunity, as there are for all these ingredients where there is only data from a single study available,” added Dr Gafner.
“And obviously there are some plants which are commonly used for IBS, such as chamomile or myrrh, where there is no clinical data as a single ingredient (although chamomile is an ingredient in STW 5, and STW 5-II, two products that are included in the study).”
State of the science
For the new systematic review and meta-analysis, Dr Hawrelak and his co-workers identified 33 double-blind and placebo-controlled trials investigating the effects of Western herbal medicines on IBS-related symptoms or quality of life.
The vast majority of these trials (17) used peppermint essential oil, one trial used peppermint oil in one arm and aniseed essential oil, while other trials used a range of other Western herbal medicines.
The meta-analyses suggested good efficacy and safety for peppermint essential oil in the short-term management of IBS.
ABC’s Dr Gafner noted that, in view of the ongoing debate about the safety of ingesting essential oils, “the data on adverse events ingesting peppermint seemed particularly worth looking into.
“It’s noteworthy that in the most widely used dosing range (ca. 300-1400 mg oil/day), adverse events were more frequent in the peppermint group compared to placebo, but these adverse events, mainly heartburn and perianal burning, were considered to be mild,” said Dr Gafner.
Reductions in IBS symptoms were also observed for Aloe vera and asafetida, while efficacy from single rigorously-designed clinical trials was also observed for the herbal formulas STW 5, STW 5-II and Carmint, along with Ferula assa-foetida, Pimpenella anisum oil, the combination of Curcumin and Foeniculum vulgare oil, and the blend of Schinopsis lorentzii, Aesculus hippocastanum, and peppermint essential oil.
“Based on this positive preliminary data, all of these herbal preparations should be further evaluated in follow-up studies to see if these promising initial results can be replicated, and ideally in trials of longer duration (e.g., at least 12 weeks),” wrote the researchers.
Irritable bowel syndrome is thought to affect about 11% of people around the world.
Despite it being considered benign, IBS does detrimentally affect quality of life and comes with a substantial economic impact.
According to Hawrelak et al., “A recent review of the economic impact of IBS found that total annual direct costs related to IBS were between £45.6 and £200 million in the UK and $1.35 billion in the USA.”
Source: Complementary Therapies in Medicine
Volume 48, January 2020, 102233, doi: 10.1016/j.ctim.2019.102233
“Western herbal medicines in the treatment of irritable bowel syndrome: A systematic review and meta-analysis”
Authors: J.A. Hawrelak et al.