The gut microbiome has become a hot topic of conversation in recent years, largely in part to the growth of the gut health movement. But what exactly does the gut microbiome refer to? The trillions of microorganisms and their genetic material that live in your digestive tract of course! Made up of mostly bacteria, these microbes are involved in a number of processes that are essential to health and wellbeing (such as metabolism, regulation of the immune system, and even brain function and mood). During digestion, gut bugs play a key role in breaking down the food we eat, encouraging optimal nutrient absorption and synthesis of vitamins such as B12. There are several factors that can influence the type and amount of bacteria one might find living and thriving in the gut. Genetics, stressful events, illness and lifestyle behaviours all play their part. However, of all the lifestyle choices we make, none is more important to the health of our gut microbiota than diet.
What defines a healthy gut?
It can be a little tricky to describe exactly what a healthy gut might look like, simply because no one person has the same bacterial fingerprint. We each live in an environment slightly different to the person next to us, with habits and surroundings that are unique to us. I.e. while we may eat in a similar way, it’s most likely that my dietary pattern is going to differ a little (or a lot) from yours, and yours from mine. Ideally, a healthy gut has the right balance of bacteria and is able to go about it’s several important jobs, without experiencing gastrointestinal distress or disrupting physical or mental wellbeing. Sometimes the ratio of beneficial and potentially harmful bacteria can become imbalanced, and this is known as Dysbiosis. Dysbiosis is linked to a number of conditions including inflammation and Irritable Bowel Syndrome, and is associated with digestive disturbances such as bloating, excess gas, abdominal pain and altered bowel habits.
Probiotics
Probiotics are live microorganisms that can offer health benefits when consumed in the right amount. They’re found in supplements (in capsule, powder and liquid form), and some naturally fermented and fortified foods that haven’t been heat-treated (e.g. yoghurt that contains live cultures). Probiotics belong to different groups called ‘genus’, and are further classified by their ‘species’ and ‘strain’. There are many different types of probiotic supplements and products available, thanks to hundreds of different strains. Some require refrigeration, and others are fine to be kept in the pantry. Shelf-stable probiotics are created by freeze-drying live bacteria, which then lie dormant until encountering moisture. One of the main benefits of shelf-stable probiotics is their portability; you can travel anywhere with them. Supplements that contain live microbes need proper refrigeration, as some strains of live bacteria can die at room temperature. It’s also worth noting that some probiotics contain the FODMAPS inulin and fructo-oligosaccharides.
There’s emerging evidence to suggest that specific probiotic strains can be beneficial for certain illnesses and conditions.
- Certain strains from the lactobacillus, bifidobacterium and saccharomyces genera may be useful in managing symptoms related to Irritable Bowel Syndrome. More research is required to determine exactly which strains are the most beneficial in the management of IBS. Additionally, a study from the United Kingdom found increased levels of healthy bifidobacteria in the gut in patients taking a multi-strain probiotic (including strains of bifidobacteria) while following a low FODMAP diet.
- Probiotics containing saccharomyces or lactobacillus genera have been documented to reduce the risk of developing antibiotic associated diarrhoea and clostridium difficile infections in adults and children during and after a course of antibiotics.
- Saccharomyces boulardii or a mixed probiotic containing lactobacillus acidophilus and bifidobacterium may be helpful in reducing the risk of traveler’s diarrhoea. In the case of acute gastroenteritis in children, a probiotic containing lactobacillus rhamnosus GG or saccharomyces boulardii is a recommended form of treatment (alongside rehydration).
- Certain strains may play a role in the treatment and management of mild to moderate ulcerative colitis, including saccharomyces boulardii lyo CNCM I-745,coli Nissle 1917, and VSL#3 (this particular strain is also used in the treatment and prevention of pouchitis).
- Bifidobacterium animalis appears to be the most effective strain in the treatment of lactose intolerance. There is also evidence to suggest that strains found in fermented dairy products may also be beneficial (lactobacillus rhamnosus, lactobacillus reuteri, and bifidobacterium longum).
- More research is needed to determine exactly what role probiotics might play in mental health. We do know that a strong link exists between the gut and the brain, aptly titled the ‘gut-brain axis’. Watch this space!
It might be handy to think of a probiotic supplement as something that’s prescriptive. Not just any probiotic will have a particular effect, and not just any dose. If you’re interested in trialling a probiotic supplement, chat to your GP or a registered Dietitian to determine which one is most suitable for you.
Eating for a healthy gut on a low FODMAP diet
At first glance, a low FODMAP diet may seem restrictive and feel counterintuitive to good gut health (particularly the elimination phase). But once you’ve identified which foods trigger symptoms of IBS (and in what amount), you’re one step closer to consolidating a lifelong habit of eating for a healthy gut.
Gut bacteria thrive on foods rich in prebiotics, or non-digestible dietary fibres (not to be confused with probiotics!). These prebiotics feed your gut bugs in the same way that we might feed our pets! Foods that are rich in prebiotics are also often high in FODMAPS. This is because certain FODMAPs are prebiotic fibres (I’m looking at you fructan and galacto-oligosaccharide). So, how does one nurture their gut microbiome on a low FODMAP diet?
- Try and eat as diversely as possible, including a wide variety of fresh fruits, vegetables, wholegrains, nuts, seeds, and herbs and spices. This ensures you not only get a regular dose of dietary fibre, but a hit of naturally-occurring antioxidants as well. Low FODMAP foods such as firm bananas, blueberries, kiwi fruit, broccoli, green beans, red cabbage, sweet potato, potato (particularly cooked and cooled), pumpkin, rolled oats, brown rice, quinoa, konjac noodles, spelt sourdough bread (traditionally made), FODMAP Friendly certified Alpine Spelt and Sprouted Grains Bread, tinned lentils (rinsed and drained well), pepitas, chia seeds, peanuts, ground cinnamon and fresh or dried turmeric, basil and oregano are all very gut-friendly choices. Some high FODMAP foods containing prebiotics are okay to eat in a low FODMAP serving size. Download the FODMAP Friendly app to check the correct low fodmap serving size for these prebiotic-rich foods: artichokes, beetroot, pomegranate seeds, dried paw paw, buckwheat kernels, wheat-free gnocchi, wheat bran, wheat or spelt pasta that’s been cooked and cooled, mung beans, lima beans, almonds, hazelnuts, and tinned chickpeas that have been rinsed and drained well.
- Aim to regularly eat naturally fermented foods that are rich in probiotics. Low FODMAP picks include plain yoghurt (Greek / European style, lactose-free, or dairy-free coconut that contains live cultures), plain lactose-free Kefir, Tempeh, unpasteurised red cabbage Sauerkraut (low FODMAP in a ½ cup serve), and miso paste. In some low FODMAP cheeses, beneficial bacteria can survive the aging process. Opt for mozzarella, cheddar and cottage cheese.
Keep an eye on consumption of foods and drinks containing excess sugar, artificial sweeteners, saturated and trans fatty acids, and caffeine. Including large amounts of these things in the diet may be detrimental to your gut health, disrupting the balance of bacteria in the gut and potentially exacerbating IBS symptoms. If drinking alcohol, it’s best to do so in moderation.
So, what’s the prognosis?
Individuals with diagnosed IBS may experience a mild improvement in symptoms when taking a probiotic supplement containing lactobacillus, bifidobacterium or saccharomyces genera. It’s important to note that it’s advised to only take one type of probiotic supplement at a time, and do so regularly for a minimum of 4 weeks while monitoring symptoms (benefits may take time to occur). A multi-strain probiotic (containing bifidobacteria) may be of particular benefit to those following a low FODMAP diet.
For the rest of us though, the most current research suggests that if you’re healthy (and have a gut that functions normally), there’s no particular benefit in taking a probiotic. Rather than focusing on one specific type or amount of ‘good bacteria’, it could be more worthwhile (and cheaper!) to put your energy into the broader behaviours that encourage a healthy gut microbiome. These include eating a varied and well-balanced diet, exercising regularly, getting enough good-quality sleep, spending time in nature (gardening counts!), and reducing your exposure to stress.
Written by: Lauren Sedger (Nutritionist)
Reviewed by: Charmaine Duong (Dietitian)
