The below provides a selection of probiotics that have been clinically studied specifically in relation to IBS (23). Note that some of the probiotics returned particularly good results and others less so, demonstrating that not all probiotics are equal when it comes to IBS.
Bifidobacterium longum/infantis 35624
A 2005 study of both IBS-C and IBS-D patients discovered that Bifidobacterium infantis 35624 normalised bowel habit among IBS patients with diarrhoea or constipation by increasing bowel movement frequency in constipated patients and reducing bowel movement frequency in those with diarrhoea (5).
In a 2006 study of women with IBS found that Bifidobacterium Infantis 35624 at a dose of 1 x 10(8) CFU reduced abdominal pain, bloating, bowel dysfunction, incomplete evacuation, straining, and the passage of gas at the end of the 4 week study (6).
A 2008 experiment with mice ingesting Bifidobacterium infantis 35624, found that the probiotic significantly enhanced immune cell production increasing the immune cell response to the introduction of harmful pathogens in the gut. There were also increases in cells that suppress inflammation so the probiotic reduced the inflammatory response to pathogenic infection (9).
A 2018-2022 study of IBS patients achieved a significant decrease in IBS severity and improvements in quality of life of the patients by Bifidobacterium longum 35624 after a 30 day treatment period (8).
A study published in 2023, found Bifidobacterium longum 35624 significantly reduced gas, bloating, abdominal pain and diarrhoea in IBS patients over 8 weeks (7).
Assessment: Good results found in lots of studies.
A 2000 study of Lactobacillus plantarum (DSM 9843) administered to patients with IBS for 4 weeks decreased symptoms of pain and flatulence (1).
A 2001 study found improvement in IBS symptoms including abdominal pain from Lactobacillus plantarum (DSM 9843) over 4 weeks (2).
A study in 2012, showed a reduction in abdominal pain and bloating in IBS patients from Lactobacillus plantarum (DSM 9843) after 4 weeks (3).
A 2021 study found that longer term use of Lactobacillus plantarum 299v over 12 weeks found a significant and continuous reduction of overall IBS symptoms (4).
Assessment: Good results found in lots of studies.
LAB4
This multi strain probiotic contains Lactobacillus acidophilus CUL60 (NCIMB 30157) and CUL21 (NCIMB 30156), Bifidobacterium lactis CUL34 (NCIMB 30172) and Bifidobacterium bifidum CUL20 (NCIMB 30153) (10).
In a 2009 clinical trial it was found to improve IBS symptom severity, quality of life, pain and bowel habit over the 8 week trial period (10).
A 2008 study found a reduction in abdominal pain of IBS patients with Lactobacillus acidophilus SDC2012, 2013 (18).
In 2016 Lactobacillus acidophilus NCFM alleviated moderate to severe abdominal pain in IBS patients (17).
Assessment: Good results in relation to pain.
L. reuteri DSM 17938 and ATCC PTA 6475
A 2023 study found IBS symptom reduction including improving stool consistency from twice a day administration of Limosilactobacillus reuteri DSM 17938 and ATCC PTA 6475 after 6 weeks of a 14 week study (32)
In 2012 it was reported that E coli Nissle 1917 administration to IBS patients achieved significant symptom improvement by 11 weeks of the probiotic with the best response from those with gastroenteritis or antibiotics prior to IBS onset. (29)
In a 2015 study, IBS patients taking E coli Nissle 1917 only experienced significant improvement in specific IBS symptoms such as sleep improvements in IBS-D patients, but no improvements for IBS-C patients and increasing constipation for IBS-M patients. (30)
50 children with IBS were given Lactobacillus GG or a placebo over 6 weeks in a 2005 study, but the study found that Lactobacillus GG was no better than placebo for pain or other gastrointestinal symptoms apart from perceived abdominal distension (19).
Assessment: Not great results for IBS in children.
Lactobacillus casei Shirota
At least 30% reduction in the average IBS symptom score was the target for a 2016 study when administering Lactobacillus casei Shirota to IBS patients. However, this target was not achieved (21).
Assessment: Poor results in relation to reduction in IBS symptoms.
This is the bacterial strain found in the product called Yakult.
Lactobacillus reuteri ATCC 55730
A 6 month trial of Lactobacillus reuteri ATCC 55730 reported in 2005, returned results that were no better than placebo and did not find improvements in IBS symptoms with the probiotic (22).
Assessment: Poor results in relation to reduction in IBS symptoms.
Saccharomyces cerevisiae CNCM I-3856
A 2015 study found that Saccharomyces cerevisiae CNCM I-3856 reduced abdominal pain scores, but did not affect stool frequency and consistency (15).
In 2016 it was reported that Saccharomyces cerevisiae CNCM I-3856 does not improve intestinal pain and discomfort in IBS patients, though may have helped those with constipation (16).
A 2020 study achieved improvements in abdominal pain and stool consistency in IBS-D, IBS-C, and IBS-M patients using Saccharomyces cerevisiae CNCM I-3856 (14)
Assessment: Mixed results.
Saccharomyces boulardii
A 2011 study found that Saccharomyces boulardii, a beneficial yeast, improved quality of life for both IBS-D and IBS-M patients, but was not significant in symptom reduction and bowel frequency and stool consistency did not change (13).
In 2015 Saccharomyces boulardii decreased inflammatory markers and improved quality of life of IBS-D patients (12).
Assessment: Not great results for IBS-D & IBS-M (the only IBS types in those studies).
VSL#3
A multi-strain probiotic containing Streptococcus thermophilus, Bifidobacterium breve, Bifidobacterium lactis (previously classified as B. longum), Bifidobacterium lactis (previously classified as B. infantis), Lactobacillus acidophilus, Lactobacillus plantarum, Lactobacillus paracasei, Lactobacillus helveticus (previously classified as L. delbrueckii subsp. bulgaricus)
A 2003 study of VSL#3 and IBS patients found a reduction in bloating but VSL#3 had no effect on other symptoms including abdominal pain, gas and urgency. (31)
A 2018 review of clinical studies of VSL#3 and IBS patients showed a trend towards symptom improvement with VSL#3, but no clear evidence of effectiveness for IBS (11).
Assessment: Not clearly effective for IBS.
Further Reading And References
Further articles discussing probiotics in relation to IBS here: (24)(25)(26)(27)(28)
IBS Researcher 