After analyzing over 40 probiotics across 69 trials, we’ve identified the most promising probiotics for managing global IBS symptoms in IBS. Our dataset (below) is ordered based on an automated scoring system, which we further refined using additional criteria (below) to select our top choices. Here are the results of our findings.

Our Top Choice(s)

1. Unique IS-2

Two studies on Bacillus coagulans Unique IS-2 showed significant improvements in global IBS symptoms. In the first study, Sudha et al. found that children receiving the probiotic experienced a 60.6% reduction in overall IBS symptom severity over 8 weeks, with a large effect size of 1.08. Their total symptom score improved by 73.4%, with an even larger effect size (2.03). Additionally, the probiotic group reported strong global IBS symptom relief, with a notable effect size of 2.08. (1) In the second study, Madempudi et al. observed that adults in the probiotic group saw a 55.6% reduction in IBS severity, with a large effect size (1.65). Furthermore, around 19% achieved complete symptom relief, and over 64% experienced considerable relief, highlighting the significant benefits of B. coagulans IS-2 for IBS management. (2) These findings earned Unique IS-2 the #1 spot in our rankings for global IBS symptom relief.

2. Lactospore

 A study on the probiotic Lactospore found a significant reduction in IBS symptom severity. Using the Physician’s Global Assessment scale (ranging from 0 to 10, with 0 being ‘very poor’ and 10 ‘excellent’), participants taking Lactospore reported noticeably higher scores at visits 3 and 4 compared to baseline. This improvement was statistically significant (p < 0.01) with a large effect size of 1.49, reflecting a strong reduction in symptoms. (3) These findings earned Lactospore the #2 spot on our list for global IBS symptom relief.

3. De Simone

Across five studies evaluating the impact of the De Simone formulation on global IBS symptoms, the findings were mixed. While some studies showed significant improvements, others reported no notable differences between the probiotic and placebo groups. For instance, Kim et al. (4) and Tuteja et al. (5) found no statistically significant differences in overall IBS symptom scores (p = 0.37 and p = 0.13, respectively). In contrast, Guandalini et al. reported significant improvements starting as early as week 2 (p < 0.05) and persisting through week 6 (p < 0.001), with a notably large effect size of 2.01. (6) Similarly, Michail et al. found a statistically significant difference between groups (p = 0.015) with a large effect size of 1.08. (7) Wong et al. observed no significant changes in the overall population but noted improvements in male participants and those with a normal circadian rhythm who took the De Simone formulation. (8) When all studies were considered, the weighted mean effect size for global IBS symptoms was substantial (1.13), indicating that, while results vary, the De Simone formulation may offer meaningful benefits to certain subsets of IBS patients. As a result, the De Simone formulation has earned the #3 spot on our list for global IBS symptom relief.

4. DDS-1

In one study, Lactobacillus acidophilus DDS-1 was shown to improve global IBS symptoms in adults. Participants in the DDS-1 group started with a baseline mean IBS-SSS (Irritable Bowel Syndrome Symptom Severity Score) of 310.90. By day 42, they achieved a significant reduction of 133.4 points, surpassing the Minimum Clinically Important Difference (MCID) of 50 points. This improvement was statistically significant compared to the placebo group (p < 0.001), with a moderate to strong effect size of 0.85. On average, participants in the DDS-1 group experienced a 42.9% relative decrease in their total IBS-SSS score. (9) These results earned DDS-1 the #4 spot in our rankings for global IBS symptom relief.

5. Bio-Kult (Multi-Strain)

In the study on Bio-Kult for IBS-D, participants experienced a 223-point reduction in their overall IBS Symptom Severity Score (IBS-SSS) by the 5-month follow-up, representing a 66.9% decrease from baseline. Significant symptom improvement compared to the placebo group was observed as early as the 1-month mark. By the end of treatment at month 4, the effect size was moderate (0.79), and the results remained highly significant (p < 0.001). (10) These results earned Bio-Kult the #5 spot in our rankings.

Honorable Mentions

Paraghurt

In one study, after 4 weeks of treatment, 81% of participants in the probiotic group were rated by physicians as having either “significant improvement” or “improvement” in their symptoms. This result was statistically significant compared to the placebo group. (11) Our independent analysis revealed an effect size of 0.85, indicating a moderate benefit from the probiotic treatment. However, due to non-specific dosing information in the study manuscript regarding the total CFU count, we’ve included Paraghurt as an honorable mention for bloating relief.

Probio-tec 

In one study, participants who received the probiotic treatment were 1.8 times more likely to report satisfactory relief of general symptoms compared to those who received the placebo. This difference was statistically significant (p < 0.01) with a moderate effect size of 0.84. (12) While we were able to find similar formulations to Probio-tec that are commercially available, we were unable to confirm if those options were compositionally the same as the probiotic studied. For this reason, Probio-tec earned an honorable mention in our rankings.

UABIa-12 

In one study, the Bifidobacterium lactis UABIa-12 group began with an average IBS-SSS (Irritable Bowel Syndrome Symptom Severity Score) of 305.45 and saw a significant improvement, with a 104.5-point reduction by day 42. This improvement exceeded the Minimum Clinically Important Difference (MCID) of 50 points and was statistically significant compared to the placebo group (p < 0.001). On average, participants in the probiotic group experienced a 34.2% decrease in their IBS-SSS score, showing a 5.4% greater improvement compared to the placebo. (9) The effect size for this change was 0.53, indicating a moderate benefit from the treatment. These findings earned UABIa-12 an honorable mention in our rankings.

Our Criteria

The probiotics in our full database (below) are automatically ranked based on their 1) effect size for overall IBS symptoms (‘Global IBS Symptoms’), and finally by 2) the quality of evidence from the studies.

For this summary, we selected our top choices based on these rankings, along with the following additional criteria: 

• Evidence Quality Score: We only included probiotics backed by studies with an evidence quality score of 75% or higher.
• Effect Size: Only probiotics that demonstrated a moderate to high effect size (>0.5) for global IBS symptom relief made the cut.
• Clear Dosing Information: Only probiotics with clear and reliable dosing data were included.
• Commercial Availability: Probiotics needed to be commercially available to consumers.

No Direct Comparisons

It’s important to note that there are no direct comparisons between the probiotics in our database across identical study methods, so we can’t definitively rank one probiotic as superior to another. The probiotics described above have shown promise for global symptom relief in IBS, but as with all probiotic supplements, always consult your healthcare provider before starting.

*Population values represent the per protocol population size from studies specifically assessing the above parameters.

*Effect sizes are reported as the weighted mean effect size across studies.

References

1. Sudha MR, Jayanthi N, Aasin M, et al. Efficacy of Bacillus coagulans Unique IS2 in treatment of irritable bowel syndrome in children: a double-blind, randomised placebo-controlled study. Benef Microbes. 2018;9(4):563-572. doi:10.3920/BM2017.0129.
2. Madempudi RS, Ahire JJ, Neelamraju J, et al. Randomized clinical trial: the effect of probiotic Bacillus coagulansUnique IS2 vs. placebo on the symptoms management of irritable bowel syndrome in adults. Sci Rep. 2019;9:12210. doi:10.1038/s41598-019-48554-x.
3. Majeed M, Nagabhushanam K, Natarajan S, et al. Bacillus coagulans MTCC 5856 supplementation in the management of diarrhea predominant irritable bowel syndrome: a double-blind randomized placebo-controlled pilot clinical study. Nutr J. 2015;15:21. doi:10.1186/s12937-016-0140-6.
4. Kim HJ, Camilleri M, McKinzie S, et al. A randomized controlled trial of a probiotic, VSL#3, on gut transit and symptoms in diarrhoea-predominant irritable bowel syndrome. Aliment Pharmacol Ther. 2003;17:895-904.
5. Tuteja AK, Talley NJ, Murtaugh MA, Loc-Carrillo CM, Stoddard GJ, Anderson GL. Randomized, double-blind placebo-controlled trial to assess the effect of probiotics on irritable bowel syndrome in veterans with Gulf War illness. Fed Pract. 2022;39(10):410-417. doi:10.12788/fp.0322.
6. Guandalini S, Magazzu G, Chiaro A, et al. VSL#3 improves symptoms in children with irritable bowel syndrome: a multicenter, randomized, placebo-controlled, double-blind, crossover study. J Pediatr Gastroenterol Nutr. 2010;51(1):24-30. doi:10.1097/MPG.0b013e3181ca4d95.
7. Michail S, Kenche H. Gut microbiota is not modified by randomized, double-blind, placebo-controlled trial of VSL#3 in diarrhea-predominant irritable bowel syndrome. Probiotics Antimicrob Proteins. 2011;3(1):1-7. doi:10.1007/s12602-010-9059-y.
8. Wong RK, Yang C, Song GH, et al. Melatonin regulation as a possible mechanism for probiotic (VSL#3) in irritable bowel syndrome: a randomized double-blinded placebo study. Dig Dis Sci. 2015;60:186-194. doi:10.1007/s10620-014-3299-8.
9. Martoni CJ, Srivastava S, Leyer GJ. Lactobacillus acidophilus DDS-1 and Bifidobacterium lactis UABla-12 improve abdominal pain severity and symptomology in irritable bowel syndrome: randomized controlled trial. Nutrients. 2020;12(2):363. doi:10.3390/nu12020363.
10. Ishaque SM, Khosruzzaman SM, Ahmed DS, Sah MP. A randomized placebo-controlled clinical trial of a multi-strain probiotic formulation (Bio-Kult®) in the management of diarrhea-predominant irritable bowel syndrome. BMC Gastroenterol. 2018;18(1):71. doi:10.1186/s12876-018-0788-9.
11. Gade J, Thorn P. Paraghurt for patients with irritable bowel syndrome: a controlled clinical investigation from general practice. Scand J Prim Health Care. 1989;7(1):23-26.
12. Jafari E, Vahedi H, Merat S, Momtahen S, Riahi A. Therapeutic effects, tolerability and safety of a multi-strain probiotic in Iranian adults with irritable bowel syndrome and bloating. Arch Iran Med. 2014;17(7):466-470. doi:10.0141707/AIM.003.

When selecting our top probiotic picks, we ensure they are commercially available and backed by high-quality evidence, with an average score above 75% for the relevant symptom parameters. The probiotics must also demonstrate a moderate to high effect size (>0.5) for these symptoms. If there are more than five candidates, we limit our top picks to the best five based on the effect size for relevant symptoms and Global IBS symptoms, as well as evidence quality. This ensures our recommendations are practical and reliable.

When selecting our top probiotic picks, we ensure they are commercially available and backed by high-quality evidence, with an average score above 75% for the relevant symptom parameters. The probiotics must also demonstrate a moderate to high effect size (>0.5) for these symptoms. If there are more than five candidates, we limit our top picks to the best five based on the effect size for relevant symptoms and Global IBS symptoms, as well as evidence quality. This ensures our recommendations are practical and reliable.