Evidence for use of probiotics in IBS
As a registered dietitian in gut health, a large portion of my practice involves caring for people
with irritable bowel syndrome, or IBS. Irritable bowel syndrome is currently the leading
gastrointestinal diagnosis in North America with an estimated prevalence of 12% in the US and
Canada. 1,2 While considered a disorder of gut-brain interaction, as opposed to a disease state,
the core symptoms of IBS – pain, bloating, gas and elimination changes – are often severe
enough to create a significant impact on daily activities and quality of life for those who suffer
from the diagnosis. 1,3
Gut Bacteria and IBS
Abnormal gastrointestinal motility and visceral hypersensitivity in the gut-associated nervous
system have been the focus of IBS research for many years. 1 However, given the nature of the
gas, bloating and elimination changes in IBS, these symptoms may also plausibly be related to
changes in the gut microbiota…so what does the research say? 1
It would appear that the gut microbiota of those with irritable bowel syndrome differs from
that of healthy people and it is now the subject of ongoing research. 1,4 One 2019 systematic
review of 24 studies suggests there is a significant difference–both in the absence or presence
of certain bacteria–in the gut microbiota in those with IBS 4 . However, heterogeneity is such that
no two studies included in the review reported the same differences. 4
This speaks to the emerging theory that IBS is in fact not one thing, but a heterogeneous set of
factors contributing to a similar symptom profile. 1,2,4 Various risk, environmental and host
factors, ranging from antibiotic use and early life stressors to altered intestinal permeability and
food intolerance have been identified as contributing to symptoms. 1,2,4 While pathophysiology
may be complex, and symptoms diverse, there are a variety of treatment efforts that appear to
have a positive effect on many.
Current Nutritional Therapies for IBS
Take for example the low FODMAP diet, where foods high in fermentable carbohydrates (oligo-,
di-, and monosaccharides and polyols) are strictly eliminated for 4-8 weeks. 5,6 This diet produces
positive symptom improvement in approximately 50-87% of trial subjects and in my own
practice, I find it quite reliable (if not adequate sole lifestyle therapy) for those with IBS-D. 5,6
FODMAPs have multiple effects, including acting as osmotic sugars in the gut and fermentation
substrates for gut microbiota. 2,5 Early evidence also suggests that the low FODMAP diet
decreases both the number and diversity of the gut microbiota, which is one reason why low
FODMAP diets should not be used for long-term symptom management. 5,6 This fermentation
effect, coupled with the observation that the gut microbiota is altered in IBS lays the
groundwork for exploring the efficacy of probiotics in irritable bowel syndrome.
Probiotics for IBS
In 2019, The Canadian Association of Gastroenterology released practice guidelines that
suggest offering probiotics for symptom improvement in IBS, based on evidence from 51 clinical
trials. 2 Other reviews have also suggested that probiotics, particularly multi-strain formulations,
may be of benefit in irritable bowel syndrome. 7,8
While the research suggests that probiotics may improve symptoms through a variety of
means, from improving gut barrier integrity to beneficial interactions of bacteria-derived short
chain fatty acids with the host immune and nervous system. 8 However, the evidence on
probiotics suffers from a couple of main issues: first, significant heterogeneity and second, the
amount of placebo effect observed in trials on IBS therapies. 7-9 The first problem stems from the
enormous amount of probiotics available for both study and purchase and varying dosages and
treatment length. It is also worth noting that each individual strain of probiotic bacteria is
biologically unique and while there are sometimes redundant metabolic functions preserved
between strains, the research on one individual strain or combination of strains cannot
confidently be extrapolated to another strain.
The second issue speaks to the incredibly complex nature of IBS and the deep interconnection
between the brain and gut that occurs in the condition; in the research, results need to be
strong in order to remain significant versus the placebo effect.
Bio-K+ for IBS
In Canada, there are currently five retail probiotics with Health Canada indications for irritable
bowel syndrome; the Clinical Guide to Probiotics Available in Canada (www.probioticchart.ca) is
an excellent tool for evaluating the level of evidence and indications for the various probiotics
on the market.
Bio-K+ is the most recent evidence-based probiotic entry into IBS category; the Health Canada
indication was given for improving quality of life in IBS-D based on the results of a recent clinical
trial published in Beneficial Microbes. 9
In this trial, 113 participants with IBS-D, IBS-C and IBS-M were randomized in a 2:1 ratio to
receive either 2 - 50 Billion (100 Billion total dosage) capsules of Bio-K+ at breakfast, or a
placebo. 9 Participants were asked to journal daily bowel movements and pain in addition to
completing research-validated IBS-QOL (Quality of Life) and IBS-SSS (Symptom Severity Scale)
questionnaires at weeks 0, 6 and 12. 9
At 12 weeks, stool consistency, stool frequency, days with high pain and quality of life improved
for those with IBS-D subtype. 9
- Stool consistency improved by 90% (versus placebo)
- 67% fewer diarrhea episodes
- Subjects had 2x fewer days with pain scores higher than 6/10
- Quality of life scores improved by 65%
Taking an integrative approach
Irritable bowel syndrome represents just how complex the interactions between the gut, brain,
immune system and gut microbiota really are. In my practice, I take an integrative approach
that includes nutritional therapy, stress reduction and other lifestyle tools along with evidence-
informed supplementation like Bio-K+ probiotics. While it can be challenging to navigate these
complexities both as someone with IBS or health practitioner, improvements are absolutely
Chey, William D., Jacob Kurlander, and Shanti Eswaran. "Irritable bowel syndrome: a clinical review." JAMA 313.9 (2015): 949-958.
Moayyedi, Paul, et al. "Canadian Association of Gastroenterology clinical practice guideline for
the management of irritable bowel syndrome (IBS)." Journal of the Canadian Association of
Gastroenterology 2.1 (2019): 6-29.
Schmulson, Max J., and Douglas A. Drossman. "What is new in Rome IV." Journal of
neurogastroenterology and motility 23.2 (2017): 151.
Pittayanon, Rapat, et al. "Gut microbiota in patients with irritable bowel syndrome—a systematic review." Gastroenterology 157.1 (2019): 97-108.
Whelan, Kevin, et al. "The low FODMAP diet in the management of irritable bowel syndrome: an evidence‐based review of FODMAP restriction, reintroduction and personalisation in clinical
practice." Journal of human nutrition and dietetics 31.2 (2018): 239-255.
Halmos, Emma P., and Peter R. Gibson. "Controversies and reality of the FODMAP diet for
patients with irritable bowel syndrome." Journal of gastroenterology and hepatology 34.7 (2019):1134-1142.
Liang, Ding, Ning Longgui, and Xu Guoqiang. "Efficacy of different probiotic protocols in irritable bowel syndrome: A network meta-analysis." Medicine 98.27 (2019).
Dale, Hanna Fjeldheim, et al. "Probiotics in Irritable Bowel Syndrome: An Up-to-Date Systematic Review." Nutrients 11.9 (2019): 2048.
Preston, K., et al. "Lactobacillus acidophilus CL1285, Lactobacillus casei LBC80R and
Lactobacillus rhamnosus CLR2 improve quality-of-life and IBS symptoms: a double-blind,
randomised, placebo-controlled study." Beneficial Microbes 9.5 (2018): 697-706