What is IBS?

IBS is a chronic functional disorder that affects the gastrointestinal system. Those with IBS typically experience abdominal pain and altered bowel habit. Subtypes of IBS include IBS with constipation (IBS-C), IBS with diarrhoea (IBSD), mixed type (IBS-M) and unclassified (IBS-U).

The pathophysiology of IBS is not clearly understood, and it is suggested that the condition is multifactorial, affected by environmental, inherited, and psychosocial factors.

Suggested mechanisms include visceral hypersensitivity, dysfunction in the gut–brain axis, disturbances in the epithelial barrier integrity causing an abnormal change in intestinal permeability, altered gastrointestinal motility, immune activation, abnormal enteroendocrine signalling, as well as dysbiosis in the gut microbiota.

Currently, there is no definitive investigation for IBS as no biomarker has been found. Symptoms of irritable bowel syndrome can vary widely and also change over time, so healthcare practitioners should encourage you to describe all your symptoms and how they affect your daily life before asking you any specific questions. It is also important to rule out other gastrointestinal disorders including coeliac disease, irritable bowel syndrome.

As there is no gold standard diagnosis for IBS, there can be inconsistencies amongst diagnosis. Alongside difficulties diagnosing IBS, there is no specific or standardised therapy.


IBS treatment

Although IBS is a non-fatal condition, the symptoms are experienced as troublesome for those affected and the condition is associated with increased rates of depression and anxiety, as well as economic challenges, hence often leads to severe reduction in quality of life (QoL).

Medication, diet and lifestyle are the main treatment options for IBS. Neither pharmacological treatment nor diet changes tend to completely eliminate symptoms, therefore alternative approaches to improve symptoms and improve life for those affected are researched. Many people are also interested in using friendly bacteria supplements to help manage their IBS.


Friendly Bacteria and IBS

Studies comparing the gut microbiota of IBS patients to healthy controls have suggested an altered microbiota profile in IBS, and specific gut microbiota profiles have been associated with particular symptoms and severity of the disease. Therefore, using friendly bacteria has been suggested as a way to help manage and control IBS. Studies in both animals and humans have suggested that different strains of friendly bacteria may improve abdominal pain and reduce visceral hypersensitivity by modulation of expression of neurotransmitters and receptors involved in the modulation of pain. Many studies have looked into the benefits of friendly bacteria for IBS. Friendly bacteria are strain-specific, this means that they will have different mechanisms of actions depending on their genus, strain and strain code. Therefore, when choosing a friendly bacteria supplement it must have the following -

  • A bacteria should have its strains defined and proof of delivery of viable strain(s) at an efficacious dose at the end of shelf-life established and, if it is a drug, then the benefit has to outweigh the risk for its use

Friendly bacteria supplements for IBS have been increasingly researched for use in IBS with over 60 randomised controlled trials assessing IBS symptom and quality of life benefits of friendly bacteria compared to placebo.


Which bacterial strains show a benefit?


Bloating is caused by the build-up of gas caused when bacteria digest fibre we are unable to digest. In those with IBS, they can be more sensitive to this bloating, or an unbalanced gut microbiome may contain bacteria that produce more gas.

The bacterial blend VSL#3 has been researched in those suffering from IBS-D. Twenty-five patients with IBS-D were randomly assigned to receive VSL#3 powder or matching placebo twice daily for 8 weeks. The friendly bacteria was able to reduce bloating, however, did not improve any other symptoms such as abdominal pain, gas and urgency (1).



Excessive flatulence may be caused by bacteria in your large intestine. Your microbiome breaks down hard-to-digest dietary fibres and undigested food that makes it your gut. This process can result in the production of gases, which increase flatulence and cause abdominal pain. In those with IBS, their gut lining can be more sensitive to pain signals than healthy, this can make them more susceptible to abdominal pain caused by gas production.

One strain that has been clinically tested for flatulence is Lactobacillus plantarum 299v. 214 participants took the friendly bacteria supplement for 4 weeks and it was able to relieve gas and bloating in the treatment group compared to the placebo group (2).


Those with IBS-D will experience loose stools, an urgent need to go to the toilet and experience abdominal pain. Some friendly bacteria can help ease this diarrhoea.

The Saccharomyces boulardii is among the most promising of friendly bacteria for diarrhoea IBS. A study in 37 patients with IBD-D who took S. boulardii with ispaghula husk (a type of dietary fibre used to treat bowel movement issues) S. boulardii had an anti-inflammatory effect which could presumably be associated with an improvement in overall symptoms (3).



IBS-C can cause symptoms such as cramping, bloating and difficulty passing stools.

362 patients with IBS took either Bifidobacterium infantis 35624 or a placebo for 4 weeks. The bacteria was shown to improve incomplete evacuation, straining, and the passage of gas at the end of the 4-wk study (4).

Quality of life

A bacterial blend i3.1 containing the bacterial strains Pediococcus acidilactici CECT 7483, Lactobacillus plantarum CECT 7484 and Lactobacillus plantarum CECT 7485 was tested against a placebo to improve IBS symptoms. The probiotic strains demonstrated a statistically significant and clinically relevant improvement in IBS quality of life from week 3 and was able to improve gut-related anxiety by targeting the gut-brain axis (5). 


The NHS view

The NHS have started recommending probiotics for IBS. Their view is that friendly bacteria, “are thought to be helpful in managing IBS symptoms such as pain, bloating and altered bowel habits, especially diarrhoea”.

Whilst there is no current strain/combination that is currently recommended for those with IBS, the NHS states that, “it is thought that for overall symptom improvement, flatulence/wind and pain, a multi-strain product may be helpful.”


There are several types of IBS, so it is important to find a friendly bacteria supplement that works for your patient. The efficacy of the bacteria can depend on many factors including their IBS type, the bacteria and their gut microbiome.

It is also important to address the various other lifestyle and dietary factors that may impact IBS symptoms.

If you’d like to find out more about friendly bacteria and IBS, why not book a free 1:1 consultation with our nutrition team? We can also recommend diet and lifestyle changes that can make a big difference. To book your consultation, click here.




  1. Kim, H., Camilleri, M., Mckinzie, S., Lempke, M., Burton, D., Thomforde, G. and Zinsmeister, A., 2003. A randomized controlled trial of a probiotic, VSL#3, on gut transit and symptoms in diarrhoea-predominant irritable bowel syndrome. Alimentary Pharmacology & Therapeutics, 17(7), pp.895-904.
  2. Katzka, D., 2007. Efficacy of an Encapsulated Probiotic Bifidobacterium infantis 35624 in Women with Irritable Bowel Syndrome. Yearbook of Gastroenterology, 2007, pp.36-37.
  3. Abbas, Z., Yakoob, J., Jafri, W., Ahmad, Z., Azam, Z., Usman, M., Shamim, S. and Islam, M., 2014. Cytokine and clinical response to Saccharomyces boulardii therapy in diarrhea-dominant irritable bowel syndrome. European Journal of Gastroenterology & Hepatology, 26(6), pp.630-639.
  4. Stevenson, C., Blaauw, R., Fredericks, E., Visser, J. and Roux, S., 2014. PP137-SUN: Randomized Clinical Trial: Effect of Lactobacillus Plantarum 299V on Symptoms of Irritable Bowel Syndrome. Clinical Nutrition, 33, p.S71.
  5. Manichanh C, Eck A, Varela E et al. (2014) Anal gas evacuation and colonic microbiota in patients with flatulence: effect of diet. Gut 63, 401–408.