After analyzing over 40 probiotics across 69 trials, we’ve identified the most promising probiotics for managing constipation 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. Bacillus coagulans Unique IS-2

Bacillus coagulans Unique IS-2 ranked #1 based on its strong performance in both adults and children. It demonstrated significant improvements in constipation-related symptoms such as straining and incomplete evacuation.

• In adults, incomplete evacuation improved by 61.3% with an effect size of 1.55, while straining improved by 65%(effect size: 1.67). (1)
• In children, incomplete evacuation improved by 73.3% (effect size: 1.19), and straining improved by 70% (effect size: 1.19). (2)

Although these studies included various IBS subtypes, the significant improvements in constipation-related symptoms earned Unique IS-2 the top spot in our rankings.

Honorable Mention

Probio-tec also showed promising results, with a significant reduction in feelings of incomplete defecation compared to placebo (Cohen’s d = 0.77). However, it was not included in the top rankings due to its lack of commercial availability. (3)

Our Criteria

The probiotics in our full database (below) are automatically ranked based on their 1) effect size for constipation relief, followed by 2) effect size for overall IBS symptoms (‘Global IBS Symptoms’), and finally by 3) 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: Probiotics had to demonstrate a moderate to high effect size (>0.5) for constipation-related symptoms.
• 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 we do not have direct comparisons between probiotics in our database across identical groups or study methods. Therefore, we cannot definitively rank one probiotic as superior to another. Bacillus coagulans Unique IS-2 has shown promise in managing constipation-related symptoms in IBS, but always consult your healthcare provider before starting any new probiotic or supplement.

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

*Population values represent the per protocol population size from studies specifically assessing a constipation-related parameter.

References:

1. Madempudi RS, Ahire JJ, Neelamraju J, et al. Randomized clinical trial: the effect of probiotic Bacillus coagulansUnique IS-2 vs placebo on the symptom management of irritable bowel syndrome in adults. Sci Rep. 2019;9:12210. doi:10.1038/s41598-019-48554-x.
2. Sudha MR, Jayanthi N, Aasin M, et al. Efficacy of Bacillus coagulans Unique IS-2 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.
3. 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:0141707/AIM.003.