Pre, pro, and postbiotics are compounds which, while all sounding pretty similar, are actually very different in terms of their makeup. Some are fibrous, some are enzymes, and some are even alive! However, what they do all have in common is that they all work to promote optimal gut health for you.
What is gut health?
Within your intestines, you have millions and millions of bacteria and although that might sound terrifying, most of these bacteria are good for you. They help to improve your digestion, your immune system, your metabolism and much more! Some of these bacteria however are bad for you. Too much bad bacteria can lead to digestive issues and even to dysbiosis which is an imbalance of good and bad bacteria. Dysbiosis can cause constipation, diarrhoea, bloating and fatigue, and can lead to more serious problems such as Crohn’s disease and IBS. For those with IBS, controlling your gut health is a way of managing the condition by helping to alleviate symptoms.
Okay, so what exactly are Prebiotics?
Prebiotics are fibrous compounds that your body is unable to digest. As a result, these compounds pass through your upper digestive tract and end up for a while in your lower digestive tract. All the good bacteria within our intestines love to feed on these compounds, which leads to an increased growth in the good bacteria. Prebiotics preferentially feed the good or beneficial gut bacteria, helping them grow and shift the gut microbiota balance in a favourable direction, which can indirectly suppress less desirable microbes.
Can Prebiotics Help With IBS?
Prebiotics play an important role in feeding the beneficial bacteria in our gut but do they help with IBS? Some clinical studies have shown that prebiotic supplements can increase levels of Bifidobacteria, a type of beneficial gut bacteria that is often lower in people with IBS compared with healthy individuals. This has led to the suggestion that prebiotics might support IBS management.
Galacto-oligosaccharide (GOS) prebiotics, in particular, have been shown in several studies to help reduce symptoms such as bloating and flatulence in some people with IBS. Prebiotics are available as supplements, but they are also naturally present in certain fruits, vegetables, and grains, including bananas, onions, garlic, asparagus, oats, and artichokes.
You may notice that many of these prebiotic-rich foods are high FODMAP, and you’d be correct.
This might make you wonder: how can you support your gut bacteria without triggering IBS symptoms? The answer is to choose the right types and amounts of foods and to include low FODMAP prebiotic options. Several low FODMAP foods contain prebiotic fibres, such as cabbage, eggplant, drained chickpeas, kiwifruit, oats, and almonds. Including these foods is an easy way to nourish your gut bacteria while staying within your FODMAP limits, check the maximum allowed amounts in the FODMAP Friendly app.
It’s also very important to complete all three phases of the low FODMAP diet so you can identify your trigger foods and gradually reintroduce the remaining tolerable FODMAPs, including prebiotic-rich foods, back into your diet. Remember, the low FODMAP phase is a short-term intervention, not a permanent diet. While some prebiotic foods may be limited temporarily, they should eventually be reintroduced to support gut health and long-term IBS management. A low FODMAP diet is not a zero FODMAP diet, some high FODMAP foods may be tolerated in small amounts.
What about Probiotics?
Probiotics are foods or supplements that contain the living good bacteria found in your gut. As a result, when you consume probiotics, you are directly increasing the number of beneficial bacteria in your digestive tract. Probiotics are found in supplement form as well as fermented and fortified foods such as some yoghurts, kefir, unpasteurized sauerkraut, and Kombucha. (Hint: Always check the label to see if the product contains live cultures)
Probiotics and IBS
Many people with IBS have lower levels of beneficial bacteria in their gut, and probiotics may help restore some of these microbes. Probiotics are defined as live microorganisms that, when taken in adequate amounts, provide a health benefit. They come in a variety of forms in Australia, including capsules, powders, liquids, and foods like yoghurts and fermented products.
Which probiotic strains have evidence for IBS?
Clinical studies suggest that certain strains may be more helpful than others for specific IBS symptoms:
Lactobacillus reuteri – evidence is limited and mixed; single-strain products often show no consistent benefit in adults, though some combination strains and studies in children suggest symptom improvements.
Bifidobacterium infantis 35624 – shown to reduce bloating, abdominal pain, and improve bowel habits.
Bifidobacterium bifidum & B. longum – may help reduce bloating and flatulence, with modest effects.
Lactobacillus plantarum 299v – may reduce pain and bloating, particularly in IBS with diarrhoea.
Lactobacillus rhamnosus GG and L. acidophilus – mixed evidence; may help some people with bloating and gas.
How might probiotics work?
Many people with IBS have lower levels of beneficial bacteria in their gut, and probiotics may help restore some of these microbes. Probiotics are live microorganisms that, when taken in adequate amounts, can provide a health benefit. They are available in a variety of forms in Australia, including capsules, powders, liquids, and foods such as yoghurts and fermented products. Certain strains have more evidence for symptom support in IBS than others. For example, Bifidobacterium infantis 35624 has been shown to reduce bloating, abdominal pain, and improve bowel habits, while B. bifidum and B. longum may help reduce bloating and flatulence, although effects tend to be modest. Lactobacillus plantarum 299v may be particularly helpful for abdominal pain and bloating in IBS with diarrhea, whereas L. rhamnosus GG and L. acidophilus show mixed results, sometimes helping with bloating and gas. Lactobacillus reuteri has limited and mixed evidence in adults, with single-strain products generally showing no consistent benefit, although some combination strains and studies in children suggest potential improvements.
Probiotics may work in IBS by replacing missing beneficial strains, competing with less favourable bacteria, supporting gut barrier function, modifying fermentation patterns to reduce gas and bloating, influencing gut motility and sensitivity, and even interacting with the gut-brain axis to affect pain perception and mood. While generally safe, the benefits of probiotics are usually modest and vary between individuals. It is recommended to trial one product at a time for at least three to four weeks, with up to twelve weeks to evaluate its effect. If symptoms do not improve, it is best to discontinue and consider trying a different strain rather than combining multiple products. Some probiotic products, particularly synbiotics, may contain prebiotics such as inulin or FOS, which are high FODMAP and can worsen symptoms in people with IBS. Consulting a dietitian or GP is advised before starting probiotics, as strains, doses, and product quality can differ, and regular intake is needed to maintain benefits.
By choosing strains with clinical evidence and carefully monitoring symptoms, probiotics can be a safe adjunct to other IBS management strategies, such as the low FODMAP diet.
What on earth is a Postbiotic then?
When Probiotic bacteria consume Prebiotics, they create waste products called postbiotics, these can be a variety of compounds such as enzymes, cell walls, and short-chain fatty acids. Although “waste”, they are responsible for the majority of benefits that pre and probiotics give.
Postbiotics are relatively “new”, within the nutrition science community and are still not fully understood yet. Some studies have suggested that increased levels of post-biotics may contribute towards improving IBS symptoms but more research is required. Post-biotics are available as supplements in certain locations, however the best way to increase your postbiotic levels is to simply consume more pre and probiotics, increasing your postbiotics.
Summary
Prebiotics – fibrous compounds that the good bacteria in your intestines can feed on.
Probiotics – living bacteria that help to increase good bacteria numbers in your gut
Postbiotics – the beneficial by-products of when prebiotics eat probiotics
IBS patients may benefit from taking a prebiotic and/or probiotic supplement. Most pre and probiotics are easily accessible and relatively harmless and may even help to reduce symptoms, although results may vary from person to person.
If you are choosing a supplement, take your time in doing some research and work with a dietitian to find an evidence-based pre- or probiotic and make sure to stick to one type of supplement for at least four weeks and monitor your symptoms. The eventual goal on the low FODMAP diet is to be able to reintroduce and enjoy a wide variety of pre and probiotic rich foods, working with a dietitian is a great way of finding out what your individual threshold for these foods are.
