Probiotics, gut bacteria and microbiome are the latest nutrition buzzwords, but what do they actually mean? HFG dietitian and editor Brooke Delfino explains the latest health science breakthroughs and provides 10 easy steps to a healthier gut.
For decades, good health was synonymous with weight, and losing excess kilos was often the focus for improving health. But as many know, it’s a lot more complicated than that.
People with bloating and constipation may be aware of the importance of gut bacteria, but this is now becoming a mainstream health concern. Improving the diversity of the trillions of bacteria that live in the gut (the body’s main digestive tract) is now considered the foundation for good health.
Between 1000 and 1500 species of bacteria live in our gut microbiota, the name given to the bacteria, yeasts and fungi living in our digestive tract. The state of our gut microbiota may affect not just gut health, but a multitude of other health issues, such as immunity, irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), heart disease, kidney disease, skin conditions and even mental health issues like anxiety and depression.
“We now believe that gut microbiota can affect just about every organ in the body,” says dietitian Dr Megan Rossi, who is a Research Fellow at King’s College London.
“It’s early days, in that we’ve yet to determine whether intervening with diets that target gut microbes can improve the health of other organs, but that is where the science is heading. It’s looking promising in many areas, including mental health,” she adds.
“The intestine is nine metres long, with 70 per cent of our immune system lying within it, so it’s clearly essential to our immunity. We also know the microbiota produces molecules that get into our blood and can ‘talk’ to our brain and other organs.”
Scientists are now working to bring the latest research into the public domain. Meanwhile, to help apply what is already proven, Rossi offers the following 10 practical tips for good gut microbiota
1. Think diversity, not ‘good’ or ‘bad’ bacteria
“The first thing to realise is that you need to eat as wide a range of plant-based foods as possible,” advises Rossi.
“I tell people to aim for 30 different plant-based foods a week. That includes different nuts, seeds, whole grains, legumes, fruits and vegetables. Research suggests if you’re having fewer than 10 of these plant-based foods a week, your microbial diversity isn’t very strong. Vary the foods you eat from week to week, and always be open to trying new things.”
This week, add three new plant foods to your shopping trolley that you wouldn’t usually buy. For example, swap your usual zucchini for eggplant. Or if you always eat almonds, try Brazil nuts. Better still, choose a mixed nut blend for greater variety.
2. Eat fibre-rich foods
The fibre in some (but not all) high-fibre foods contains prebiotics, which ‘feed’ the beneficial bacteria that live in your gut. Foods that contain these very beneficial prebiotics include beans, legumes, artichokes and Brussels sprouts.
“Fibre is the Holy Grail nutrient,” stresses Rossi. “If you can increase the amount you eat, it will benefit pretty much every organ in your body, including your heart.
“Current guidelines recommend eating 30g fibre a day, but most of us are only eating 19g. I believe we should be aiming even higher,” asserts Rossi. “Increase the amount you eat gradually to give your body time to adjust to it,” she adds.
Open your pantry and pull out your cereal boxes to check the amount of fibre per 100g in the nutrition information panels on the packaging. If they are more than 5g fibre per 100g, then you’re doing well, but at your next shop choose cereal products that have at least 10g per 100g.
3. Try healthy fermented foods
Fermented foods are those with bacteria or yeast, such as yoghurt, kefir (fermented milk) and kombucha (fermented tea). These foods generally contain a wide range of bacteria types, so are considered beneficial for the gut microbiome.
“I try to eat fermented foods every day,” says Rossi.
“Kefir is the one with the most scientific evidence behind it. It has about 20 different types of bacteria and yeast in it, and the diversity is much greater than in yoghurt. I drink 100ml kefir a day. You can now buy kits with the kefir grain — you just add milk and keep it on your kitchen bench to ferment for a few hours, then it’s ready to drink.”
Other healthy, fermented foods to try include kimchi (spicy pickled cabbage) and sauerkraut (fermented shredded cabbage).
Take a good look in the chilled dairy aisle the next time you’re at the supermarket and choose one of the kefir products now available. If you find the taste a little strange, use it to make a morning smoothie with banana, mixed berries and a spoonful of nut butter or a handful of oats, for a filling start to your day.
4. Avoid sweeteners
They may reduce your kilojoule intake, but artificial sweeteners can also destroy the diversity of your gut microbiome.
“Evidence suggests artificial sweeteners are probably not great to include in your diet in large amounts,” Rossi says.
“Whether it’s better to have sugar instead of sweeteners depends on many factors, like your weight and medical history. It’s about balance: it’s fine to enjoy a small 30g chocolate bar every now and then, but regularly overdoing it with a big bag of sweets is never going to be a good idea
Low-fat flavoured yoghurt often contains artificial sweeteners, so swap flavoured varieties for plain yoghurt and sweeten it yourself using naturally sweet fresh fruit, such as mango, apple and blueberries, or honey in small quantities.
5. Always buy ‘live’ yoghurt
There are plenty of yoghurts on supermarket shelves these days, but they don’t all contain beneficial gut bacteria.
“Choose tubs with labels saying they contain live cultures,” Rossi explains.
“It doesn’t really matter if they’re full-fat or made from skim milk.
To ensure you’re getting enough live cultures, choose yoghurts with at least 100 million CFU (colony forming units or added probiotics).
6. Take probiotics only after antibiotics or if you have IBS
There’s no scientific evidence to suggest a probiotic supplement offers health benefits to healthy people, but studies do show specific strains of bacteria can help treat certain conditions.
“If you’re taking antibiotics, for instance, one strain of yeast called Saccharomyces boulardii halves your chance of developing diarrhoea, which affects around a third of people who are taking antibiotics,” Rossi explains.
“When it comes to IBS, one study found four probiotic supplement products on the market were effective in treating symptoms: Symprove, Alflorex/Align, Bio-Kult and VSL#3. When researchers pooled the results of further studies, they also found probiotics reduced IBS symptoms by 20 per cent,” says Rossi
Always discuss management strategies for your IBS with your doctor. It may take up to four weeks to see benefits from taking a probiotic.
7. Swap staple foods regularly
It’s so easy to do, but try not to get stuck in a dietary rut eating the same staples all the time.
“If you eat rice a lot, put wild rice, quinoa, buckwheat or other ancient grains on your plate instead,” Rossi advises.
“Even eating yellow and green capsicum, as well as red, will help. If you’re buying chickpeas, buy a can of four bean mix instead, or butter beans, red kidney beans and black beans too. Likewise with pasta, swap plain white varieties for wholegrain or legume.
If your family is hesistant to try whole grains and legumes, go half-half. Mix brown and white rice together or halve the amount of mince in bolognese and add a can of lentils to bulk it out. They won’t even notice!
8. Follow the Med-diet to boost mood
“Some studies suggest eating a high-fibre, Med-style diet of fruit, veg, legumes, extra-virgin olive oil and whole grains can improve depression,” Rossi says.
“That’s not to say people on medication should stop taking their pills. Rather, it suggests a high-fibre Mediterranean diet alongside taking their medication may improve their mood.”
Make extra-virgin olive oil your go-to oil of choice and use it for everything. Drizzle it over salads, use it when pan-frying or roasting, and substitute it for butter when baking.
9. Forget the low-carb fad
“The ramifications of the low-carb diet trend, without a medical recommendation, are quite worrying because fibre is a type of carbohydrate,” explains Rossi.
“In the short term, you can lose weight, but you can also damage your gut bacteria, which may have consequences in the long run, such as higher colon cancer risk.”
Use our recipe search function to look for high-fibre recipes.
10. Don’t do the low-FODMAP diet unaided
This diet involves avoiding a type of poorly absorbed carbohydrate found in foods such as onions, garlic, lentils, cabbage, cauliflower, broccoli and wheat. You may be tempted to follow the low-FODMAP diet to ease IBS symptoms such as bloating and diarrhoea, but it requires the supervision of a qualified dietitian, warns Rossi.
“The low-FODMAP diet can be very useful for some types of IBS, but it shouldn’t be the first port of call,” she says.
“Many FODMAPs are essentially prebiotics, so by cutting them out you could be starving your gut bacteria of food. Also, the diet should only last for up to six weeks. After that, FODMAPs should be reintroduced with the help of a dietitian, to identify what your tolerance is.”
If you are currently following a low-FODMAP diet without having consulted a dietitian, look for a dietitian in your area for professional guidance.
Top 5 gut-friendly foods
Add these foods to your daily diet to boost your gut health:
- Wholegrain breads and cereals – barley, oats, rye, buckwheat and wild rice
- Fermented dairy foods – kefir, yoghurt and cheese
- Legumes – beans, chickpeas and lentils
- Fruit and veg – colourful, high-fibre fresh produce, preferably with skin on (berries, sweet potato, corn, tomatoes, broccoli and bananas)
- Nuts and seeds – almonds, cashews, walnuts, flaxseeds and chia seeds.
Article sources and references
- Better Health Channel. 2014. Fibre in food. Accessed February 2022.https://www.betterhealth.vic.gov.au/health/healthyliving/fibre-in-food
- Dai et al. 2013. Probiotics and irritable bowel syndrome. World J Gastroenterol. 19(36): 5973–80.https://pubmed.ncbi.nlm.nih.gov/24106397/
- Dairy Australia. 2021. Do all yoghurts have probiotics? Accessed February 2022.https://www.dairy.com.au/dairy-matters/you-ask-we-answer/do-all-yoghurts-have-probiotics
- Fayet-Moore et al. 2018. Dietary Fibre Intake in Australia. Paper I: Associations with Demographic, Socio-Economic & Anthropometric Factors. Nutrients. 10(5): 599.https://pubmed.ncbi.nlm.nih.gov/29751656/
- Harper et al. 2018. The role of bacteria, probiotics and diet in irritable bowel syndrome. Foods. 7(2): 13.https://pubmed.ncbi.nlm.nih.gov/29373532/
- Jacka et al. 2017. A randomised controlled trial of dietary improvement for adults with major depression (the ‘SMILES’ trial). BMC Medicine. 15(1): 23.https://bmcmedicine.biomedcentral.com/articles/10.1186/s12916-017-0791-y
- Kelesidis, T & Pothoulakis, C. 2012. Efficacy and safety of the probiotic Saccharomyces boulardii for the prevention and therapy of gastrointestinal disorders. Therap Adv Gastroenterol. 5(2): 111–25.https://pubmed.ncbi.nlm.nih.gov/22423260/
- McDonald et al. 2018. American Gut: an Open Platform for Citizen Science Microbiome Research. mSystems. doi: 10.1128/mSystems.00031–18.https://pubmed.ncbi.nlm.nih.gov/29795809/
- Monash University. 2021. Probiotics for IBS.Accessed February 2022.https://www.monashfodmap.com/blog/prebiotics-and-probiotics-what-are-they/