When choosing a probiotic it is best to opt for one which has plenty of research behind it. Consumers want something that has been ‘scientifically tested’. The best type of research that we can look for is a clinical trial, because it shows how the probiotic performs in real people with real health conditions, compared to a placebo.

So, when recommending a probiotic for IBS (Irritable Bowel Syndrome) it is a good idea to look for one which has been shown in clinical trials to be beneficial.

Luckily, probiotics have been shown in many clinical trials to help those with IBS. However, it is important to take a few things into account when looking at these trials, to help clients and patients make the best decision about which probiotic to go for. First of all, there are different types of IBS, so for a start it is essential to figure out what type of IBS you are dealing with. Then, we need to be aware that there are so many different types of probiotics (called different strains) and they all have different properties. In this FAQ we hope to make things clear for health care practitioners by outlining the different types of IBS, and then looking at which strains of probiotics have been shown in clinical trials to be best for supporting health with each type of IBS.

To find out more about probiotic strains and what exactly a 'strain' is read our article about probiotic strains.

IBS-D (D for Diarrhoea)

Saccharomyces boulardiiThose with IBS and frequent bouts of diarrhoea are suffering with IBS-D. They should consider the probioticSaccharomyces boulardii which has been shown in many clinical trials to help people suffering with diarrhoea. This is a unique probiotic microorganism because it is actually a yeast – in fact it is the only yeast which is friendly enough to be called a probiotic. It has over 50 years of research, and is actually recommended in many hospitals in countries throughout mainland Europe for people with diarrhoea. As well as diarrhoea caused by IBS it has also been shown to be helpful for diarrhoea associated Inflammatory Bowel Disease (IBD) and antibiotic-associated diarrhoea and traveller’s diarrhoea. OptiBac Probiotics ‘Saccharomyces boulardii’ (formerly known as 'For bowel calm') contains 5 billion live microorganisms per capsule and is, to our knowledge, the best value S. boulardii supplement in the UK.

For more information on this probiotic read our FAQ 'What is Saccharomyces boulardii?', see some of the clinical trials on this strain, and read some of the customer feedback on Saccharomyces boulardii (many have mentioned they have IBS).

It is also worth considering a general probiotic formula, containing friendly bacteria, to be taken alongside S. boulardii. As mentioned above, S. boulardii is a friendly yeast, and as such it has very different properties to friendly bacteria. For example, S. boulardii does not colonise in the gut, it is instead considered to be a transient probiotic which moves through the gut without staying for long. So whilst S. boulardii has properties which make it particularly helpful for those with IBS-D, it is also a good idea to also take a probiotic containing friendly bacteria, which will colonise in the gut for much longer and boost gut health in general, to support the work of S. boulardii. See 'For every day EXTRA Strength' (formerly known as 'For daily wellbeing EXTRA Strength') for a good, high quality, daily probiotic which can be taken alongside Saccharomyces boulardii.

IBS-C (C for Constipation)

Bifidobacteria & fibreThose with IBS who find it mainly causes them to have constipation are suffering with IBS-C. These individuals should consider taking 'Bifidobacteria & fibre' (formerly known as OptiBac Probiotics 'For maintaining regularity'). This natural supplement contains a specific probiotic strain called Bifidobacterium lactis BB-12®, which has so many clinical trials that it is thought to be the most well researched strain in the whole family of Bifidobacteria. In the clinical trials this strain of probiotic has been shown to be particularly helpful for relieving constipation, and promoting regular, well formed bowel movements, which are easy to pass, as well as supporting gut health in general. This product also contains the prebiotic Fructooligosaccharides, making it naturally high in fibre.

One double-blind, randomised, placebo-controlled clinical trial involved over 100 women with a tendency towards constipation who were given a supplement including Bifidobacterium lactis BB-12® and prebioticsi. Intestinal transit time (the time it takes for food to move through the gut and come out the other end as a bowel movement) decreased significantly in the probiotic group by -40.9% compared to the placebo group which saw a decrease of just -13.8%. This means that those who took the B. lactis BB-12® supplement were no longer constipated and had normal bowel movements compared to those who took the placebo. Read more of the clinical trials on this strain here.

IBS and Bloating

Most people with IBS suffer with some bloating. At certain times the bloating can really flare up, when aggravated by factors such as stress, or eating particular foods. During a particularly bad period of bloating the probiotic 'One week flat' (formerly called 'For a flat stomach'), which is a 7 day probiotic supplement, may be helpful. This product comes in sachets and is designed to particularly help with symptoms of bloating, as well as support gut health in general.

OptiBac Probiotics ‘One week flat’ contains Lactococcus lactis Rosell-1058, a probiotic strain which produces two specific enzymes to help with digestion of foods which often exacerbate bloating. α-glucosidase can help to digest starch (e.g. bread, pasta), and ß-galactosidase can help to digest lactose (e.g. milk, ice cream). This supplement also contains L. acidophilus Rosell-52, which has been shown to reduce the negative effects of stress on the body, often a trigger in IBS.

'One week flat' is one of the most popular probiotic supplements in our range. Find out what customers think about this product here.

IBS-A (A for alternating digestive symptoms)

For every day EXTRA strength Many people with IBS find they have alternating constipation and diarrhoea. So for a few days they may be constipated, but then once the bowels get moving they find they have to run to the loo until the bowels settle down again. This is also known as IBS-M (M for mixed type). These individuals can try out 'Bifidobacteria & fibre' (formerly OptiBac Probiotics 'For maintaining regularity') and 'Saccharomyces boulardii' (formerly 'For bowel calm'), and take each of these as and when needed.


Another option is to simply try a general daily probiotic such as 'For every day EXTRA Strength'. Two of the strains in 'For every day EXTRA Strength', Lactobacillus acidophilus NCFM® and Bifidobacterium lactis Bi-07 have been specifically trialled in those with IBS and shown to reduce bloating and abdominal distensionii. This product is therefore ideal for anyone suffering from any type of IBS, not only to regulate bowel movements but to also specifically help relieve the general symptoms of chronic bloating, abdominal distension and abdominal cramps. See the research on our EXTRA Strength probiotic to find out more about this product and the L. acidophilus NCFM® strain, or read the customer reviews on this product. Customers wishing to take a particularly high dose of probiotics can take 2 capsules a day.

At the end of the day, everyone is different, and different IBS sufferers will have very different gut floras to one another. With probiotics it is often a case of trial and error to find which species and strains work for the individual. There is no harm, in 'mixing and matching' different products in the OptiBac Probiotics range, in fact this can often be the best way of catering for the specific needs of the individual. For example 'For every day EXTRA Strength' can safely and effectively be taken alongside any of the other products mentioned on this page. For more information on this topic, see these two FAQs: Can I take two OptiBac Probiotics at the same time? and Is it possible to overdose on probiotics?

If in doubt?

For those unsure as to what type of IBS they have, (and/or if they have IBS-U) it is probably best to choose ‘For every day EXTRA Strength’. The combination of 5 probiotic strains in this product means that it offers the most diverse properties of all the products mentioned on this page. For someone with general IBS symptoms this offers the most well-rounded approach.

Other probiotic strains

As well as the supplements available for IBS sufferers in the OptiBac Probiotics range, here are some examples of other strains which have shown promising results in clinical trials.

Bifidobacterium infantis 35624

This strain of B. infantis has been researched in those with Irritable Bowel Syndrome, with positive resultsiii . Although we have other strains of the species B. infantis in the OptiBac Probiotics range (such as B. infantis Rosell-33 found in ‘For babies & children’) because the characteristics of different strains within the same species vary greatly, this strain cannot be guaranteed to have the same benefits as B. infantis 35624 (in fact it has other benefits, like boosting childhood immunity, read more about this here). In summary, when looking for high quality probiotics it is essential to understand the meaning and importance of individual strains. Find out more about strains.

Lactobacillus plantarum Lp299v

Similarly, a specific strain of the L. plantarum species, L. plantarum Lp299v, has been clinically trialled on participants with IBS, and has been shown to reduce IBS symptomsiv. Again it is worth noting that the L. plantarum strains in our range - L. plantarum CECT 7527, L. plantarum CECT 7528 and L. plantarum CECT 7529, have not been shown to be beneficial for those with IBS, but they are helpful for reducing cholesterol levels. So again we see the importance of choosing the most suitable strain of probiotic for any given condition.

Pediococcus acidilactici CECT 7483, Lactobacillus plantarum CECT 7484 and Lactobacillus plantarum CECT 7485

This combination of friendly bacteria has been shown in a clinical trial to benefit those with IBS-DV. This trial measured improvements in the quality of life of the participants, in relation to their IBS symptoms, which is thought to be one of the most accurate ways of measuring the effectiveness of the treatment.

Probiotics with Clinical Trials

In the OptiBac Probiotics range we have more than 270 clinical trials on the various probiotic strains we use. As we have seen above, some of these trials have been conducted specifically in those with IBS, and others on people with particular symptoms of Irritable Bowel Syndrome, such as constipation, diarrhoea and/or bloating. To find out more about the clinical trials on our probiotic range, read this page.

Probiotics and IBS In Depth

IBS affects our society in huge numbers - up to 20% of the UK population are sufferers, with women twice as likely to be affected as men. Common symptoms include bloating, constipation and / or diarrhoea, and abdominal discomfort. The most commonly used diagnostic method for IBS is the Rome criteria, which measures IBS by assessing stool frequency and consistency as well as abdominal discomfort. As we have seen above, the Rome criteria classifies IBS into these subtypes:

IBS-D (diarrhoea dominant); IBS-C (constipation dominant); IBS-A or IBS-M (alternating or mixed) & IBS-U (unspecified).

Although there is no clearly defined cause of IBS, many sufferers often report that symptoms are exacerbated by dietary factors such as wheat and dairy products, which are high in FODMAPs (Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols) , and lifestyle factors such as high stress levels, as well as an imbalance in good and bad bacteria in the gut. For those particularly concerned about FODMAPs, see our FAQ about the suitability of probiotics for a low FODMAPs diet.

Several studies have documented the link between gut microflora and IBS symptoms. Sufferers often have lower levels of beneficial gut bacteria e.g. Bifidobacterium species, and increased levels of gut pathogens e.g. Clostridium species. We have seen above how specific probiotics in the OptiBac Probiotics range can help with specific IBS symptoms. In addition, generally speaking, supplementing with a high quality probiotic may help reduce IBS symptoms in the following ways:

  • Probiotic bacteria give a huge boost to the numbers of friendly bacteria in the gut, so less space is available along the gut lining for colonisation of ‘bad’ microorganisms, which often cause excess gas production and digestive discomfort.
  • Beneficial microflora help break down foods which may exacerbate IBS.
  • Healthy flora may play a part in modulating the nervous system in the gut, called the enteric nervous system, therefore reducing the impact of stress on the gut, which is a key factor for many people with IBS.

In a nutshell

For individuals suffering with IBS-D, consider ‘Saccharomyces boulardii’. For those with IBS-C, consider ‘Bifidobacteria & fibre’, and for any other type of IBS, look at ‘For every day EXTRA Strength’.

For a full list of all the probiotic species & strains in all of our products, see our Full Ingredients FAQ.

i Malpeli, A. et al (2012) Randomised, double-blind and placebo-controlled study of the effect of a synbiotic dairy product on orocecal transit time in healthy adult women. Nutr Hosp 27 4 1314-9.

iiRingel-Kulka, T. et al (2011) Probiotic bacteria Lactobacillus acidophilus NCFM and Bifidobacterium lactis Bi-07 versus placebo for the symptoms of bloating in patients with functional bowel disorders: a double-blind study. J Clin Gastroenterol 45 6 518-25.

iii Whorwell PJ et al. (2006) Efficacy of an encapsulated probiotic Bifidobacterium infantis 35624 in women with irritable bowel syndrome. Am J Gastroenterol 101 7 1581-90.

iv Niedzielin K et al. (2001) A controlled, double-blind, randomized study on the efficacy of Lactobacillus plantarum 299V in patients with irritable bowel syndrome. Eur J Gastroenterol Hepatol 13 10 1143-7.

V Lorenzo-Zúñiga V et al. (2014) I.31, a new combination of probiotics, improves irritable bowel syndrome-related quality of life. World J Gastroenterol 20 26 8709-16.