Short answer: Probiotics and prebiotics both interact with the microorganisms living in your gut, but they work in different ways. Probiotics are specific live microorganisms that have been shown to provide a health benefit when consumed in adequate amounts, while prebiotics are substances that are used by microorganisms in the body and provide a health benefit. Both may play a role in supporting gut health, but their effects depend on the individual and the specific probiotic or prebiotic being used.
Long answer:
Your digestive system is home to a large and diverse community of microorganisms, including bacteria, viruses and fungi.
Together, these microorganisms and their genetic material are commonly referred to as the gut microbiome.
The gut microbiome interacts with many aspects of health, including digestion, the immune system and the breakdown of certain components of food.
You may have heard that probiotics can add “good bacteria” to your gut while prebiotics “feed” them. While this can be a useful way to remember the difference, the science is a little more complicated.
What Are Probiotics?
Probiotics are live microorganisms that, when consumed in adequate amounts, provide a health benefit.
Probiotics can be found in some foods and dietary supplements.
Commonly studied probiotic microorganisms include certain strains belonging to groups such as Lactobacillus and Bifidobacterium, although there are many others.
Importantly, probiotics aren’t all interchangeable.
Different probiotic strains can have different effects, which means a probiotic that has evidence for one particular health condition may not provide the same benefit for another.
This is why choosing a probiotic based simply on the number of bacteria or strains listed on the packaging doesn’t necessarily mean it will be more effective.
What Are Prebiotics?
Prebiotics are substances that are selectively used by microorganisms in the body and provide a health benefit.
Many recognised prebiotics are types of carbohydrate or fibre that aren’t completely digested in the upper gastrointestinal tract.
Instead, they reach the large intestine where they can be used by certain gut microorganisms.
Examples of recognised prebiotic compounds include:
- Inulin
- Fructooligosaccharides (FOS)
- Galactooligosaccharides (GOS)
Prebiotics occur naturally in a variety of foods, so supplements aren’t necessarily required to include them in your diet.
Which Foods Contain Prebiotics?
Foods that can provide prebiotic compounds or support a varied intake of dietary fibre include:
- Garlic
- Onion
- Leeks
- Asparagus
- Jerusalem artichokes
- Legumes
- Wholegrains
- Some fruits and vegetables
- Slightly green bananas
- Cooked and cooled potatoes, rice and other sources of resistant starch
Rather than focusing on one particular “gut health” food, eating a varied diet containing a range of plant foods and sources of dietary fibre can help support a diverse range of gut microorganisms.
However, increasing certain fibres quickly can cause symptoms such as bloating, wind or abdominal discomfort in some people.
People with conditions such as Irritable Bowel Syndrome (IBS) may also tolerate particular types of fermentable carbohydrates differently.
Are Fermented Foods the Same as Probiotics?
Not necessarily.
This is an important distinction.
Foods such as yoghurt, kefir, kimchi, sauerkraut, tempeh and kombucha are produced through fermentation.
Some fermented foods contain live microorganisms when you eat them, but this doesn’t automatically make them probiotic foods.
For a microorganism to be considered a probiotic, it must be identified and have evidence showing that it provides a health benefit when consumed in an adequate amount.
Some yoghurts and other products may contain specifically added probiotic strains, while other fermented foods simply contain live cultures.
Fermented foods can still form part of a healthy and varied diet even when the microorganisms they contain don’t meet the scientific definition of a probiotic.
Do Probiotics Improve Gut Health?
Sometimes — but it depends on the probiotic and why it is being used.
Research has identified benefits from particular probiotic strains or combinations for some gastrointestinal conditions and circumstances.
However, this doesn’t mean that every probiotic supplement will improve everyone’s gut health.
The effects of probiotics can depend on:
- The particular microorganism and strain
- The dose
- The condition or symptom being addressed
- How long it is taken
- The individual taking it
This is why a product labelled simply as a “gut health probiotic” isn’t necessarily appropriate for every person or every digestive concern.
Do You Need to Take a Probiotic Supplement?
Not necessarily.
You don’t need to take a probiotic supplement simply because you want to look after your gut health.
For many people, a varied and balanced diet containing adequate fibre and a range of plant foods is an important foundation for supporting digestive health.
There may be circumstances where a particular probiotic is appropriate, but it is better to select one based on evidence for the specific reason you are taking it rather than choosing a supplement at random.
If you have persistent gastrointestinal symptoms, it is also important not to assume that your gut bacteria are the cause.
Symptoms such as ongoing abdominal pain, bloating, diarrhoea, constipation or changes in bowel habits can have many possible causes and should be appropriately assessed.
Can Prebiotics Cause Bloating?
Yes, they can.
Because many prebiotics are fermented by microorganisms in the large intestine, increasing them can lead to increased gas production.
For some people this causes few or no symptoms, while others may experience:
- Bloating
- Wind
- Abdominal discomfort
- Changes in bowel habits
This doesn’t necessarily mean prebiotics are “bad” for your gut.
It may simply mean that the type or amount needs to be adjusted to suit your individual tolerance.
This can be particularly relevant for people living with IBS or other gastrointestinal conditions.
Is More Always Better?
No.
This applies to both probiotics and prebiotics.
Taking a supplement containing more bacterial strains or a higher number of microorganisms doesn’t automatically make it better.
Similarly, suddenly adding large amounts of fibre or prebiotics to your diet may cause uncomfortable gastrointestinal symptoms.
The goal should be to find an approach that is appropriate for your health, diet, symptoms and individual tolerance.
What Else Supports a Healthy Gut?
Gut health isn’t determined by one food, supplement or bacterial strain.
Your overall dietary pattern and lifestyle are important.
Depending on your individual needs, this may include:
- Eating a varied range of plant foods
- Including adequate dietary fibre
- Including wholegrains, vegetables, fruits, legumes, nuts and seeds where tolerated
- Drinking adequate fluids
- Regular physical activity
- Getting adequate sleep
- Avoiding unnecessary dietary restriction
If certain foods regularly trigger gastrointestinal symptoms, removing increasingly large numbers of foods without professional guidance may make it more difficult to meet your nutritional requirements.
Key Takeaways
- Probiotics and prebiotics are not the same thing.
- Probiotics are specific live microorganisms that provide a demonstrated health benefit when consumed in adequate amounts.
- Prebiotics are substances used by microorganisms in the body that provide a health benefit.
- Not all dietary fibre is technically a prebiotic.
- Not all fermented foods are probiotics.
- Different probiotic strains can have different effects.
- A probiotic that may help one condition isn’t necessarily useful for another.
- You don’t necessarily need probiotic or prebiotic supplements to support gut health.
- A varied diet containing a range of plant foods and sources of fibre can help support the gut microbiome.
- Persistent gastrointestinal symptoms should be appropriately assessed rather than assumed to be caused by an imbalance in gut bacteria.
How WLC Medical Can Help
At WLC Medical in Belmont, our Accredited Practising Dietitians provide evidence-based nutrition advice tailored to your individual health, dietary needs and gastrointestinal symptoms.
A Dietitian can help you understand your current diet, identify appropriate sources of fibre and prebiotics, and determine whether particular dietary strategies or supplements may be appropriate for you.
Rather than following a one-size-fits-all approach to “gut health”, nutrition advice can be tailored around your symptoms, food preferences, nutritional requirements and individual tolerance.
Related Articles
Continue learning about nutrition and digestive health:
- Can a Dietitian Help with IBS? (Coming March 2027)
- Understanding Food Labels (Coming Soon)
- What Is Resting Metabolic Rate (RMR) and Why Is It Important?
As the Health Hub grows, additional nutrition and gut-health articles can be linked here.
Need Help with Your Gut Health or Nutrition?
If digestive symptoms or food choices are making it difficult to know what to eat, one of our Accredited Practising Dietitians can help you develop an individualised approach based on your needs.
To speak with our friendly team or book an appointment, call (08) 6263 7778, or book online through our website.
If you are experiencing persistent or unexplained gastrointestinal symptoms, blood in your stool, unexplained weight loss, severe abdominal pain or other concerning symptoms, please speak with your GP or seek appropriate medical assessment.
References
- World Gastroenterology Organisation. Probiotics and Prebiotics – Practice Guideline.
- International Scientific Association for Probiotics and Prebiotics (ISAPP). Consensus definitions and guidance relating to probiotics, prebiotics and fermented foods.
- National Center for Complementary and Integrative Health (NCCIH). Probiotics: Usefulness and Safety.
- Peer-reviewed research relating to probiotics, prebiotics, fermented foods and the gut microbiome.
Last reviewed: September 2026
This article is intended for general educational purposes only and should not replace personalised medical or nutrition advice. Individual gastrointestinal symptoms, dietary requirements and tolerance vary. If you have persistent digestive symptoms or concerns about your gut health, please speak with your GP, an Accredited Practising Dietitian or another appropriate healthcare professional.
