What are probiotics?

Probiotics are 'good' bacteria that live naturally in your digestive system (gut). They are part of your gut microbiome. There are many different strains (types) of probiotics that have different health effects.

Your gut microbiome is a collection of trillions of microorganisms living inside your gut. It includes:

• bacteria
• viruses
• fungi (including yeasts)
• other microorganisms

Your gut microbiome plays important roles in your overall physical and mental health. A healthy gut microbiome can help with:

• digestion
• metabolism
• production of some vitamins
• supporting the immune system

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 things influence the type and amount of probiotic bacteria you have in your gut microbiome. This includes your:

• lifestyle (exercise, diet, stress)
• medicines
• genetics

You can include probiotics in your diet in the form of probiotic-rich foods or supplements to improve your gut microbiome.

What are the health benefits of probiotics?

Probiotics offer various health benefits when you take them in foods, drinks and dietary supplements.

Gut symptoms

Probiotics can help with gut symptoms such as:

• reducing diarrhoea caused by antibiotics
• shortening the length and frequency of diarrhoea
• reducing irritable bowel syndrome (IBS) symptoms

Immune health

Probiotics can help your immune system by:

• acting as a barrier against harmful microorganisms
• supporting it when you have an infection
• helping to prevent upper respiratory (airway) tract infections
• reducing the risk of infections while you are in hospital
• managing allergic responses

Health benefits for females

Probiotics can also improve the vaginal microbiome. This helps reduce the risk of developing fungal and bacterial vaginal infections. There is also early evidence that probiotics may help with infertility and polycystic ovary syndrome.

Health benefits for males

There is evidence that probiotics may improve hormone levels and reproductive function in males.

Health benefits for babies and children

Babies and children can sometimes benefit from probiotics.

Research shows that probiotics may help reduce their risk of eczema. It may also help prevent a condition called necrotising enterocolitis (NEC). Probiotics also help prevent some breathing-related symptoms in children with cystic fibrosis.

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

Not all probiotics are the same. Each strain (type) 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.

Different strains of probiotics have different health benefits.

What types of food contain probiotics?

Probiotics are added to some dietary supplements. They are also naturally found in many fermented foods and dairy items. 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 good for your health.

Prebiotics are found in high fibre foods. They travel along the gut into your large intestine to feed your gut microorganisms, helping your:

• gut
• immune system
• hormone production
• 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 may help 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.

If you are taking antibiotics, your doctor may suggest that you take probiotics. This is because antibiotics kill both good and bad bacteria. This can disrupt your gut microbiome and cause nausea and diarrhoea. Probiotic supplements can help restore your natural gut microbiome.

Where can I get probiotic supplements?

Probiotics are usually available from:

• pharmacies
• supermarkets
• health food stores

You can get probiotic supplements in many formulations, including as:

• capsules
• powders
• sachets

The types and amount of probiotics found naturally in foods are not always known and can vary. 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.

The amount and type of probiotics in dietary supplements is controlled. The amount of probiotics required as treatment is uncertain. Your doctor will tell you how much and when to take them.

When should I see my doctor?

It's a good idea to talk to your doctor or dietitian if any of the following apply to you:

• 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 such as bloating, upset stomach or lots of gas. This happens because your gut microbiome changes when you take probiotics. Your doctor can adjust your dose to help these symptoms. These side effects are most common in your first week of taking probiotics.
• You have a medical condition or take regular medicines and are not sure if probiotics are right for you.

Do probiotics have any side effects or risks associated with them?

Probiotics are associated with side effects including:

• bloating
• gas ('wind')
• diarrhoea

Probiotics should not be taken by people who are immunocompromised (have a weak immune system). This includes if you:

• are very unwell
• are undergoing chemotherapy
• are having an organ transplant
• have HIV or AIDS
• are taking immunosuppressive medicine
• have recently undergone surgery

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.

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

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

Other helpful resources include the following:

• The Royal Children's Hospital has a fact sheet on probiotics for babies and children.

You can also call the healthdirect helpline on 1800 022 222 (known as NURSE-ON-CALL in Victoria). A registered nurse is available to speak with you 24 hours a day, 7 days a week.