Probiotics are everywhere at the moment. Many people try probiotics, believing they help IBS without understanding which strain, dose, or symptom they are supposed to help.

Probiotics are foods or supplements that contain live bacteria. These microbes are similar to the ones living in your gut microbiome. It’s believed that by restoring a healthy gut microbiome, you can relieve IBS symptoms like bloating, abdominal pain, and bowel changes.

But is this true? Do probiotics help IBS? And are some strains better than others? Find out below.

Why Probiotics Might Help IBS

Irritable bowel syndrome (IBS) is linked to gut sensitivity, altered motility, immune signalling, and changes in gut-brain communication. All these effects are partly mediated by the gut microbiome (the microbial community living in your gut).

Probiotics can influence the bacterial balance, reduce gas production, and support the gut barrier. Certain species can even soothe inflammation and influence pain signalling.

That said, probiotics aren’t an automatic cure. But they may prove effective in some individuals, depending on the strain, dose, and person.

What Does the Evidence Say?

Anyone can claim that probiotics improve IBS. But with dozens of potential strains, the evidence can be mixed. Here’s what some of the evidence indicates:

• Probiotics may help IBS, but the evidence is mixed. NICE says people with IBS can try probiotics for at least four weeks, while the American College of Gastroenterology suggests against them for global IBS symptoms because the evidence is of very low quality.

• The strain matters more than the word “probiotic”. One trial found Bifidobacterium infantis 35624 improved pain, bloating, bowel dysfunction, straining, and gas, but only at a specific dose.

• Some strains may help with pain and bloating. A placebo-controlled trial found Lactobacillus plantarum 299v improved abdominal pain and bloating after four weeks.

Indeed, these two strains, Bifidobacterium infantis 35624 and Lactobacillus plantarum 299v, are the most studied for overall IBS symptoms. Other potentially beneficial species include Bifidobacterium bifidum, Saccharomyces cerevisiae, and Bacillus coagulans but the specific strains need to be identified.

Are Probiotics Better for IBS-D, IBS-C, or Bloating?

IBS isn’t a single condition. It’s categorised into three sub-types: IBS with diarrhoea, IBS with constipation, and mixed. Not every strain is suitable for all types of IBS.

For people who experience bloating and gas, Bifidobacterium bifidum may be worth considering. It’s found in some fermented foods like yoghurt, kefir, and sauerkraut. Supplements are also available.

For IBS-D, Lactobacillus plantarum is supported by the latest research. It’s found in yoghurt and sauerkraut. The bacterium also appears to help with bloating.

For IBS-C, no specific strain has yet been identified. In one meta-analysis of 10 studies, probiotics were believed to reduce constipation. However, the quality of research was questioned.

How Long Should You Try a Probiotic?

Probiotics don’t work overnight. It can take days or weeks to notice the effects. A fair trial usually means taking one probiotic consistently for at least 4 weeks, while tracking symptoms. Some guidelines even suggest trying the probiotic for up to 12 weeks, then stopping if there is no clear improvement.

You’ll want to have a clear way to track symptoms, so you can compare results over time. Here are some things to track:

• Bloating

• Pain

• Stool frequency

• Stool consistency

• Urgency

• Side effects

Avoid adding multiple probiotics at once. It can irritate the bowel, and it makes it impossible to know what helped or worsened symptoms.

What Makes a Good IBS Probiotic?

The best probiotics for IBS are clear, evidence-based, and contain no filler ingredients. Look for a clearly named strain, not just species. It should list how many CFUs (colony-forming units) and how long it lasts. There should be minimal additional ingredients.

All probiotics are required to follow Good Manufacturing standards. Ideally, there will also be human IBS studies behind the supplement or a particular strain. This makes it more likely that the product is relevant to IBS symptoms.

Be wary of vague “gut health” claims, very high CFU counts with no explanation, or products that include added ingredients such as inulin, FOS, sweeteners, or lactose, which may worsen symptoms in some people with IBS.

Still Struggling with IBS Symptoms?

Probiotics are worth trying for IBS. However, they’re not a complete answer for everyone. If your symptoms are persistent, unpredictable, or affecting your confidence around food, IBS may not be the only explanation.

IBS symptoms can overlap with SIBO, bile acid diarrhoea, coeliac disease, inflammatory bowel disease, lactose intolerance, post-infectious IBS, or pelvic floor dysfunction.

The Functional Gut Clinic provides access to a range of testing options to help you understand what’s going on in your bowel. We provide expert analysis of the results and send a copy to your doctor, who can advise you on any necessary treatments or further investigations.

Learn more about IBS symptoms and testing.