Fibre, fermented foods and FODMAPS - what do I really need for a healthy gut?

For hundreds of years, it was believed that bugs were bad and removing all bacteria from your body was the best way to improve your health. Wrong!

While some bacteria can cause harm, we’ve now come to understand that the trillions of bacteria that live in your body actually perform incredibly important functions that help keep you healthy and happy.

Our nutritionist, Steph, answers five of the most common questions about gut health, its impact on your wellbeing and how diet can improve the balance of your gut bacteria.

What is gut flora?

The gut flora is a colony of microorganisms in the gut and in medical terms is called the gut microbiome. It is a delicately balanced system that operates like the ecosystem in a rainforest. The microbiome includes trillions of bacteria, fungi and viruses that help the body to produce vitamins and amino acids, and are even important for normal immune function. Stress, illness, antibiotics and food choices can all negatively affect the delicate balance of the gut microbiome.

How can my gut impact my health? Can it cause weight gain? Affect immunity? Trigger depression?

The bacteria in your gut has a direct impact on your health and is associated with a number of diseases and health conditions. An imbalance in the gut microbiome can lead to toxic by-products and inflammation in the gut. Research has shown this can contribute to problems such as obesity, diabetes, heart disease, skin diseases (such as atopic dermatitis and psoriasis), inflammatory bowel disease, and depression.

On the flip side, nurturing your gut bacteria and creating a balanced microbiota can improve absorption of nutrients, boost immunity, help regulate digestion and improve your mood.

Can foods help restore my gut health?

Absolutely! You can change your gut bacteria almost immediately with your food choices. Research shows dramatic changes in gut bacteria can occur just days after adopting a new diet.

A plant-based, high fibre diet is a good place to start. People who eat more fibre have a greater diversity of bacteria and this is important because each type of bacteria plays a different role in keeping us healthy. Good gut bacteria also love fructans - a type of carbohydrate that is found in certain fruits and vegetables including bananas, onions, garlic, leeks, asparagus, chicory root, soybeans, and wholegrain foods like wheat, rye and barley. Inulin, a prebiotic fibre found in artichoke as well as a range of packaged food, is also great for supporting a healthy gut.

Opting for some meat-free days can also help to improve your gut health. Studies show that consuming vegetarian diets high in wholegrains and legumes simultaneously increases beneficial gut bacteria and decreases bad gut bacteria compared to diets high in animal meats.

What is the difference between probiotics and prebiotics? And do I need them both for good gut health?

Probiotics and prebiotics are essential for gut health as they work together to create a well-balanced gut microbiome.

Probiotics are live bacteria that are naturally found in your gut and food. They can reduce the number of harmful bacteria and provide new live bacteria. This is particularly important after a course of antibiotics because antibiotics can impact the balance of the microbiome. Fermented foods are a great source of probiotics - think kefir, yoghurt (with live cultures), kimchi, miso and sauerkraut.

Prebiotics are fibres that feed the healthy bacteria and are important in maintaining a healthy and balanced gut. They lay the groundwork for probiotics to flourish. Prebiotic-rich foods include fruits, vegetables, beans and wholegrains.

Is a FODMAP diet better for gut health? What about going gluten-free?

FODMAP is an acronym of the scientific names that belong to a group of carbohydrates (Fermentable Oligo-, Di-, Mono-saccharides and Polyols), which have been associated with causing digestive issues in some people. People who have been diagnosed with Irritable Bowel Syndrome may be prescribed a diet that avoids FODMAPs to help manage their condition. This link with digestive issues led to the myth that a FODMAP diet is better for gut health, but for most people this is not true. Unless you have been medically diagnosed, there is no reason to avoid FODMAPs. In fact, many foods high in FODMAPs are also a rich-source of prebiotics and probiotics, such as garlic, onion, asparagus and cultured yoghurt.

If you do think that you have sensitivities to FODMAPs it is best to discuss this with your health care professional and/or a dietitian. There is no “one-size-fits-all” approach to low FODMAP diets, and after the initial FODMAP elimination phase, your healthcare professional or dietitian will be able to work with you to gradually reintroduce different foods to pinpoint which individual FODMAPs are triggering your symptoms and how much you can tolerate. It is important to determine the level of FODMAPs that can be comfortably tolerated, so that the prebiotic effects of FODMAPs can be enjoyed and the diet is not overly restricted.

Similarly, unless you have a medical diagnosis of coeliac disease or gluten intolerance, there is no reason to avoid gluten to improve your gut health. Many foods that contain gluten are rich sources of fibre, which is important for diversity of gut bacteria and often the easiest way to improve your diet.

If in doubt, always speak to your health care professional or find a dietitian to get advice tailored to your needs.

 Gut-friendly meal ideas

• Tempeh and vegetable stir-fry 
• Roast sweet potato (kumara) and coriander salad 
• Pumpkin and chickpea satay 
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Want more information?

Our nutrition fact sheets, created by accredited dietitians, provide the latest nutrition and lifestyle information to help you understand which foods are the best to eat. Click here to see the gut health nutrition fact sheets.