Gut health

What is gut health and gut microbiome?

Your gut is your gastrointestinal system and includes your stomach, intestines and colon. It digests and absorbs nutrients from food and excretes waste.

There is no clear definition of gut health, and it can mean something different for researchers, medical professionals and the community. Throughout this page, we refer to gut health as having a healthy gut microbiome and limited digestive symptoms.

About 200 different species of bacteria, viruses and fungi live in your large intestine. The bacteria and other micro-organisms in your gut are known as your gut microbiome. The bacteria help to break down food, turning it into nutrients your body can use.

Certain types of bacteria in your gut may contribute to some diseases. Some microorganisms are harmful to our health, but many are beneficial and necessary for a healthy body.

We are learning that the variety of bacteria in your gut is an important indicator of the health of your microbiome.

The health of your gut can impact both your physical and mental health.

Many factors, including the foods you eat, can impact the type of bacteria found in your digestive tract. What we eat can have short-term and long-term effects on our gut microbiome environment.

Why gut health is important

The gut breaks down the foods you eat and absorbs nutrients that support your body’s functions.

The importance of the gut to our overall health is a topic of increasing research in the medical community. Research is showing us that our gut microbiome can affect every organ in our body.

It is understood that there are links between gut health and:

• the immune system
• mental health
• autoimmune diseases
• endocrine disorders – such as type 2 diabetes
• gastrointestinal disorders – such as irritable bowel syndrome and inflammatory bowel disease
• cardiovascular disease
• cancer
• sleep
• digestion.

A higher level of diversity in gut bacteria is an important indicator of the health of your microbiome.

While research is ongoing, it appears that your gut health plays an important role in your overall health.

Signs of an unhealthy gut

Your gut microbiome can be affected by:

• stress
• too little sleep
• lack of physical activity
• eating too many ultra-processed foods
• smoking and drinking alcohol
• taking antibiotics.

The gut microbiome is also affected by things we cannot control, such as our environment, age, birth mode and whether we were breast-fed or bottle-fed as a baby.

While we cannot use one specific measure for our gut health, some signs that you may have poor gut health include:

• digestive symptoms – such as gas, bloating, constipation, diarrhoea and heartburn
• sleep disturbances or fatigue
• mood/emotional state – such as high stress, low mood or anxiety
• high frequency of infectious illnesses – such as the common cold.

How to improve your gut health

You may be able to improve your gut health through lifestyle and diet changes.

Dietary fibre in foods can improve your gut health as it can help keep us regular, reduce the risk of bowel cancer and feed the healthy bacteria in our gut.

Wholefoods, such as fruits, vegetables, legumes, wholegrains and nuts,
may prevent the growth of some bacteria linked to diseases and inflammation.

Our lifestyle, for example physical activity, good sleep and stress reduction are also good for gut health.

Gut health and diet

Your gut bacteria are influenced by what you eat. It is important to give them the right fuel to have a balanced gut microbiome.

The best way to maintain a healthy microbiome is to eat a range of fresh, wholefoods, mainly from plant sources like fruits, vegetables, legumes, beans, nuts and wholegrains.

Eat a high fibre diet

Fibre is important for our gut health for many reasons. Fibre can affect the function of our gut, for example, the digestion and absorption of nutrients, how quickly or slowly things move through and the quality of our stools.

The breakdown of fibre by our gut bacteria can also create important products which can influence the development of gastrointestinal conditions such as bowel cancer.

Fibre has other benefits to our health apart from the gut, for example, reducing our risk of developing heart disease and type 2 diabetes.

Fibre is only found in foods that come from a plant. Australian adult women should be aiming to eat at least 25g of fibre a day, and men 30g.

Foods that are high in fibre include:

• vegetables
• beans and legumes
• fruit
• bread and cereals
• nuts and seeds.

Prebiotic fibres, which are not found in all high fibre foods, may be especially helpful for our gut microbiome, as they can act as a fertiliser for the healthy bacteria in our gut.

They are found in some types of:

• vegetables – for example leek, onion and garlic
• legumes – for example chickpeas, beans and lentils
• wholegrains – for example rye bread, barley and oats
• nuts – for example pistachios, cashews and almonds.

Eat a diverse range of food

Eating a wide range of fruits and vegetables ensures you’re including a whole range of vitamins, minerals and nutrients in your diet.

The diversity of food on your plate can help lead to a more diverse microbiome, which is an indicator of a healthy gut microbiome.

Aim to eat at least 30 different types of plant-based foods a week.

Limit ultra-processed foods

Eat foods that are as close to their natural state as possible to support your gut health.

While almost all foods have had some kind of processing, it is best to eat foods that are minimally processed. These foods retain their nutritional value and do not usually have added sugar, salt, unhealthy fats or additives such as emulsifiers and artificial sweeteners, all of which may impact your gut health.

Unprocessed foods include fruits, vegetables, wholegrains, unflavoured dairy, eggs, seafood, poultry and lean red meat. Ultra-processed foods include deli meats such as ham and salami, many breakfast cereals, ready-made meals, sweet desserts and many packaged snacks such as chips.

Drink water

Water is the best fluid to drink and provides benefits to gut health.

Water assists with the breakdown of food, so that your body can absorb nutrients. Water also assists with softening stools, helping prevent constipation.

Drinking plenty of water may also be linked to increased diversity of bacteria in the gut.

Eat foods rich in polyphenols

Polyphenols are plant compounds that may beneficially impact our gut microbiome.

Foods rich in polyphenols include:

• herbs and spices
• colourful fruits and vegetables
• nuts and seeds
• green and black tea
• coffee
• cocoa and dark chocolate.

Eat slowly

Chewing your food thoroughly and eating slowly may reduce digestive discomfort such as gas, pain and bloating.

Eat fermented foods

Fermented foods have undergone a process in which their sugars are broken down by yeast and bacteria.

Fermented foods include:

• yoghurt
• kimchi
• sauerkraut
• kefir
• kombucha
• tempeh.

While research into fermented foods is limited, the bacteria found in some fermented foods have been linked with digestive health and other benefits.

Gut health and breastfeeding

Breastfeeding helps an infant develop a healthy gut microbiome, which may help protect against certain health conditions later in life.

Gut health and exercise

Regular cardiovascular exercise such as walking and cycling can stimulate the muscles of the gut to move digestive contents through the body.

Exercise can also positively affect the gut microbiome.

Gut health and stress

Stress can impact your gut health. It’s important to look after your mental health and wellbeing to maintain your gut health.

What you eat, your gut health and your mental health are all linked.

Manage your stress levels by exercising regularly, getting enough sleep, socialising, using relaxation techniques and eating well.

Gut health and sleep

Not getting enough or sufficient quality of sleep may impact your gut microbiome and may contribute to digestive discomfort.

Gut health and probiotic supplements

It is best to improve your gut health through food and other lifestyle factors rather than supplements.

There are many nutrients in wholefoods that cannot be packaged into a single supplement. Nutrients in foods also interact with each other in a helpful way and this cannot be replicated in a pill.

Many people are interested in taking probiotic supplements. If you’re in good health, it is generally not necessary to take a probiotic for your gut health.

In some cases, there is research to support taking a probiotic, however just like medications, you need to take a specific probiotic for the health condition you are trying to manage.

Before taking probiotics or any other supplement, it’s a good idea to speak to an accredited practising dietitian and your general practitioner to see if it’s safe and which one might work.

Gut health and antibiotics

While antibiotics can be very important and useful, they can also have a negative impact on your gut microbiome.

Antibiotics aim to kill the harmful bacteria when you have an infection or illness, but in doing so they can remove some of the beneficial bacteria in your gut.

Myths about gut health

There are no miracle cures for good gut health.

There’s no scientific evidence that individual foods or any other product will rapidly heal an unbalanced gut microbiome.

There’s also no scientific evidence that colon cleansing improves health or is beneficial at all.

Research into gut health is relatively new and understanding of this complex topic is developing. Be careful of non-evidence-based information about gut health. Focusing on eating healthily with the tips suggested on this page is the best evidence we have so far.

Where to get help

• Your GP (doctor)
• A dietitian
• Dietitians Australia
• Food and Mood Centre, Deakin University