What are probiotics?

Probiotics are 'good' bacteria that live naturally in your digestive system (gut). They are part of your gut microbiome. Your gut microbiome is a collection of trillions of microorganisms living inside your gut. It includes bacteria, viruses, fungi, yeasts and other microorganisms. Your gut microbiome plays important roles in your overall physical and mental wellbeing.

A healthy gut microbiome can help with digestion and metabolism and production of some vitamins. It also supports your immune system by providing a barrier against harmful microbes. Probiotics play an important role in keeping your gut microbiome healthy by maintaining and restoring its natural balance.

Each person has their own unique gut microbiome. Many factors influence the type and amount of probiotic bacteria you have in your gut microbiome.

What are the health benefits of probiotics?

Probiotics offer various health benefits when you consume them in foods, drinks and dietary supplements, including:

• reducing gut symptoms such as, diarrhoea caused by antibiotics, shortening the duration and frequency of diarrhoea and reducing irritable bowel syndrome (IBS) symptoms
• helping your immune system by acting as a barrier against harmful microorganisms and supporting it when you have an infection
• preventing upper respiratory (airway) tract infections
• reducing the risk of developing infections while you're in hospital

Babies and children can sometimes benefit from probiotics. For example, research shows that probiotics may help reduce their risk of eczema and a condition called necrotising enterocolitis (NEC). Probiotics may also help prevent some breathing-related symptoms of children with cystic fibrosis.

If you or your child has a serious health condition, check with your doctor before deciding on a probiotic supplement.

What types of food contain probiotics?

Probiotics are added to some dietary supplements and are naturally found in many fermented foods. Examples of these foods include:

• yoghurt
• kefir
• sauerkraut
• miso
• pickles
• kombucha

What are prebiotics?

While probiotics are live bacteria, prebiotics are 'food' for probiotics. They help your probiotics grow and are beneficial for your health.

Prebiotics are found in high fibre foods. They travel along the gut into your large intestines. There, they feed your gut microbiota, helping your gut, immune system, hormone production and overall health.

Prebiotics can be found in supplements and in the following foods:

• fruits
• vegetables
• legumes such as chickpeas, lentils, red kidney beans, baked beans and soybeans
• nuts and seeds such as cashews and pistachio nuts

Synbiotics are mixtures of prebiotics and probiotics found in supplements and foods. Eating foods that contain probiotics and prebiotics will improve the health of your gut microbiome and your overall health.

When might I need a probiotic supplement?

A health professional may recommend probiotic supplements in some circumstances, such as:

• If you are taking antibiotics. This is because antibiotics kill both good and bad bacteria, which can disrupt your gut microbiome and cause nausea and diarrhoea. Probiotic supplements can help restore your natural gut microbiome. It is important to take your probiotic supplement 2 to 3 hours before or after taking antibiotics (not at the same time).
• For athletes while training, travelling or competing — probiotic supplements may help prevent catching respiratory infections or having gastrointestinal problems.

The amount of probiotics found naturally in foods is not always known and varies. This makes it hard to know if the food you eat has enough of the right type of probiotics to give you the desired health benefit. However, the amount and type of probiotics in dietary supplements is regulated.

Not all probiotics are the same. Each strain provides different health benefits. It is important to find a supplement with the strain that best supports you. If you are looking for a specific health benefit, sometimes your doctor or dietitian may recommend a probiotic supplement.

When should I see my doctor?

You should see your doctor or dietitian if:

• You want to start taking probiotics. They can advise you which supplement is best for you and how to take it.
• You are taking probiotics and have side effects of bloating, upset stomach or lots of gas. This happens because your gut microbiota changes when taking probiotics. Your doctor can adjust your dose to help these symptoms. These side effects are most common in your first week of taking probiotics.

Resources and support

See the Nutrition Australia website for more information about the gut microbiome, tips for maintaining gut health and about how food can affect your mood.

The Gut Foundation has a guide to good gut health including food and exercise suggestions.

Learn more about irritable bowel syndrome (IBS) and treatment options on the Dietitian Association of Australia website.

Use the Dietitians Australia search tool to find an Accredited Practising Dietitian (APD) to support your nutrition health needs.