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# What Is the Most Effective Probiotic for IBS?
- URL: https://www.gutminds.com/what-is-the-most-effective-probiotic-for-ibs/
- Published: 2026-08-02T11:39:18.000Z
- Updated: 2026-08-02T11:39:18.000Z
- Description: Many people with IBS mention this probiotic as one that helped them feel better. What does the research say about this bacteria?
- Author: GutMinds

[Science Based](#the-bottom-line)

I've come across the idea several times that the exact probiotic strains may not be all that important. What matters more is including different groups, such as Lactobacillus, Bifidobacterium, soil-based probiotics, and taking enough of them. 

But when it comes to IBS, one strain seems to come up again and again; *Bifidobacterium* *infantis* 35624\. It is mentioned more frequently than others in IBS-focused threads online. 

But what does the research actually say about this bacteria? 

## *Bifidobacterium* *infantis* 35624 and Inflammation

In recent years, dysbiosis has been increasingly discussed as one of the key factors behind IBS and SIBO. 

This interesting [study](https://pubmed.ncbi.nlm.nih.gov/15765388/?ref=gutminds.com) shows that when inflammation decreases, IBS symptoms such as pain, bloating and bowel movement difficulty can improve as well. 

Another group of participants received *Lactobacillus salivarius* UCC4331, but the results were not the same. This suggests that probiotic benefits may depend on the specific species and strain. 

## The Right Dose of *Bifidobacterium infantis* 35624 for IBS

How much *Bifidobacterium infantis* 35624 do you need to improve IBS symptoms?

More is not always better. 

In this [study](https://pubmed.ncbi.nlm.nih.gov/16863564/?ref=gutminds.com), researchers tested 3 different doses of *Bifidobacterium infantis* 35624 - 1 million, 100 million, and 10 billion bacteria. Surprisingly, the dose that worked best for IBS symptoms was 100 million bacteria (the middle dose). 

[*B. infantis 35624*](https://pubmed.ncbi.nlm.nih.gov/16863564/?ref=gutminds.com) *at a dose of 1 x 10(8) cfu was significantly superior to placebo and all other bifidobacterium doses for the primary efficacy variable of abdominal pain as well as the composite score and scores for bloating*, *bowel dysfunction*, *incomplete evacuation*, *straining*, *and the passage of gas at the end of the 4-wk study*.

Since high-dose probiotics can be quite expensive, it's encouraging that 100 million bacteria was enough to produce benefits for IBS. 

## *B*. *infantis* 35624 and Quality of Life

Another [study](https://pmc.ncbi.nlm.nih.gov/articles/PMC8891724/?ref=gutminds.com) on *Bifidobacterium* *infantis* 35624 looked at its effects on IBS severity and quality of life. 

The results are impressive, with 57% of patients either moving into a milder IBS category or achieving remission. 

*Thirty days of* [*treatment*](https://pmc.ncbi.nlm.nih.gov/articles/PMC8891724/?ref=gutminds.com) *with B*. *longum 35624 reduces disease severity and improves the quality of life of patients with IBS*, *particularly those with the most severe forms of IBS*.

Participants took 1 billion CFU of *B*. *longum* 35624 daily for 30 days. 

### The Bottom Line

One important detail: you'll still often see *Bifidobacterium infantis* 35624 mentioned in older studies and IBS communities online, but it is now classified as *Bifidobacterium longum* 35624\. 

I also came across another [study](https://pubmed.ncbi.nlm.nih.gov/23842110/?ref=gutminds.com) suggesting that that *Bifidobacterium infantis* 35624 may help people with chronic fatigue syndrome, ulcerative colitis, and psoriasis. 

How? By reducing inflammation, so its beneficial effects are not limited to the gut alone. 

**READ MORE**  
[Best Probiotics for IBS-D: Top 3 Evidence-Based Strains](https://www.gutminds.com/best-probiotics-for-ibs-d/)

#### 4 Sources

[Lactobacillus and bifidobacterium in irritable bowel syndrome: symptom responses and relationship to cytokine profiles](https://pubmed.ncbi.nlm.nih.gov/15765388/?ref=gutminds.com)

[Efficacy of an encapsulated probiotic Bifidobacterium infantis 35624 in women with irritable bowel syndrome](https://pubmed.ncbi.nlm.nih.gov/16863564/?ref=gutminds.com)

[Effect of **Bifidobacterium longum* 35624 on disease severity and quality of life in patients with irritable bowel syndrome](https://pmc.ncbi.nlm.nih.gov/articles/PMC8891724/?ref=gutminds.com)

[Bifidobacterium infantis 35624 modulates host inflammatory processes beyond the gut](https://pubmed.ncbi.nlm.nih.gov/23842110/?ref=gutminds.com)