Blog Post

Prebiotics and Probiotics: What You Need to Know

Good bacteria Probiotic

Did you know that we have 100 trillion bacteria living in our gut?!

While that may leave you feeling a little squeamish, don’t fear! These little guys are on our side, they play important roles in many metabolic, nutritional, physiological, and immunological processes which keep us healthy.

This includes acting as a barrier to prevent “bad” bacteria from invading and causing illness and producing nutrients that we can’t make ourselves (vitamin K, B12, folic acid, short-chain fatty acids).

There is continual evidence that suggests incorporating prebiotics and probiotics into our diet is beneficial for keeping a healthy balance of “good” gut bacteria. 

You have probably heard the terms ‘prebiotics’ and ‘probiotics’ thrown around. But what actually are they and what is the difference between the two?

What Is The Difference Between Prebiotics & Probiotics?


Probiotics are live microorganisms found in bacteria, yeast, or fungi.

Probiotics are live microorganisms (bacteria or yeast) found in certain foods, which when consumed in adequate amounts are beneficial to our bodies.

Common probiotics include the genera Lactobacillus and Bifidobacterium.

In addition to encouraging the growth of our own “good bacteria”, probiotics have been shown to increase our resistance to the common cold, decrease the risk of antibiotic-associated diarrhea, and may potentially prevent the development of allergies.

Evidence connecting conditions such as inflammatory bowel disease, irritable bowel syndrome (IBS), and obesity with an unbalanced “good” to “bad” bacteria ratio in the gut (dysbiosis), and how the use of probiotics may be of value, is still under exploration.

Not all foods which rely on the fermentation process of bacteria/yeast (such as bread) are considered probiotics. The “good” bacteria in these foods don’t always survive during food processing and exposure to oxygen, pH, and heat. They also have to combat our digestive enzymes and acidic stomach juices before reaching our intestines where they can grow and replenish the healthy bacteria already there.

  • Foods which may contain probiotics include:
  • Fermented milk products (kefir, buttermilk, Yakult)
  • Fermented vegetables (sauerkraut, pickles, kimchi)
  • Tempeh
  • Miso seasoning

Foods that contain added probiotics should state so on the product packaging – including the name of the strain of bacteria, the viable quantity, and whether the product has been clinically tested.


A prebiotic is a type of fibre found in certain foods, which promotes the growth and activity of good bacteria in the gut.

When consumed, prebiotics pass undigested through the stomach and small intestines until they reach the large intestine where they become “food” for the “good” bacteria living there.

Additional benefits of this fibre are only just emerging. Prebiotics may be associated with increased mineral absorption and improved blood glucose levels.

A wide range of foods are naturally high in prebiotics:

  • Vegetables – green peas, snow peas, corn, garlic, onion, leeks, spring onion, asparagus, beetroot
  • Fruits – banana, watermelon, nectarines, white peaches, pomegranate, dried fruit
  • Legumes – chickpeas, baked beans, red kidney beans, lentils
  • Cereals – couscous, gnocchi, pasta, rye bread/crackers, barley, oats, wheat, soybeans
  • Nuts – cashews, pistachio nuts

Keeping your digestive system happy is a foundation for good health. Try to include a variety of probiotic and prebiotic foods during the week as part of a balanced diet. Your gut will thank you!

**Please note that if you have been diagnosed with IBS and are currently following a low FODMAP diet, prebiotic foods include fructooligosaccharides (fructans, FOS) and galactooligosaccharides (GOS) which are not recommended until the re-introduction phase.

A simple way of thinking of it is:

  • Probiotics are the beneficial bacteria.
  • Prebiotics are the food for that beneficial bacteria.

How Do They Affect Our Health?

Gut health is becoming more and more pivotal in the world of nutrition. Everybody is talking about the gut microbiota, which is the collection of microorganisms in an environment. And these microorganisms include bacteria, virus, and fungi.

Foods containing probiotic cultures

There are numerous benefits of probiotics and prebiotics when effectively incorporated into the diet.

The inclusion of probiotics in the diet can help protect against pathogens, toxins, infections and help protect our gut lining. As well as helping to aid in the absorption of vitamins and minerals such as vitamin B12, iron, and magnesium.

Including more probiotics in our diets can assist with:

  • Intestinal motility
  • Bile creation and gastric secretion
  • Immune function

On the other hand, prebiotics can improve our digestion, increase absorption of nutrients and increase our immune strength. They even potentially aid in the management of our weight. They also help to stimulate the growth and survival of good gut bacteria and discourage the growth of harmful organisms.

The importance of prebiotics and probiotics in our diets is astounding. It seems these microorganisms, albeit tiny, pack a nutritional punch!

Heart Made from hands over abdomen

What Happens If We Don’t Get Enough Prebiotics & Probiotics?

If our diets are lacking in prebiotics and probiotics, pathogenic bacteria can begin to overgrow in our large intestine. This leads to poor digestion amongst other things.

As a result, this can cause bloating, flatulence, constipation, diarrhea, inflammation, damage to our gut lining, and other issues.

It is important we look after our digestive system. It is responsible for removing waste from our bodies and for the breakdown of nutrients the body needs for energy. Furthermore, our digestive system also contributes to our body’s immune system, which helps defend against pathogens and harmful bacteria.

What Are Some Foods That Are Rich In Prebiotics & Probiotics?

Probiotic Rich Foods

Probiotic-rich foods include:

  • Yoghurt
  • Kefir
  • Kombucha
  • Miso
  • Sauerkraut

Prebiotic-rich foods are typically high in fibre and some examples include:

  • Bananas
  • Soybeans
  • Jerusalem artichokes
  • Oats
  • Berries
  • Garlic
  • Onion
  • Legumes
  • Tomatoes
  • Green vegetables.

Probiotic Supplements

Using food sources of probiotics first should typically be encouraged. 

You also need to cultivate an environment for these good bacteria to survive and thrive anyway. This is where eating a wide variety of prebiotic foods becomes so necessary.

There clearly are benefits for probiotic supplements under certain circumstances though.

Some examples of this include:

There are so many more potential benefits of probiotic supplementation. The big thing to be aware of is that individual strains and supplements are typically beneficial for different goals. Unfortunately, there is no cover-all supplement that is beneficial for all conditions. It is important to consider strain specificity.

Side effects are rare but they do occur. These include a small risk of:

  • Gastrointestinal upset.
  • Amines in some products triggering headaches in those who are sensitive to them,
  • Issues in those with a histamine intolerance, for products containing histimine.
  • Bacteria or yeasts in probiotics could enter the bloodstream and cause infections in susceptible individuals.

Take Home Message

Keeping our gut bacteria happy and healthy is important for many aspects of health and wellbeing.

To do this, we need to include plenty of prebiotic and probiotic foods. These will help promote an ideal balance between good and bad gut bacteria.

Next time you are walking down the supermarket aisle, consider adding some more prebiotic and probiotic-rich foods to your shopping trolley. Your gut will thank you for it.

By Cassandra Bendall

Cassandra completed her Bachelor of Human Nutrition in 2015 at La Trobe University. Upon completion, Cassandra undertook her Honours year at La Trobe University the following year and ended the year with First Class Honours. Cassandra had the opportunity to work on the AusMed Heart Trial, which aims to prevent 12-month cardiac re-event rate using a Mediterranean diet intervention in a multi-ethnic cohort. Her Honours research focussed on the Effect of Mediterranean Diet on Visceral Fat in Australian Patients Post-Cardiac Event. Since cessation of her Honours year, Cassandra has been accepted into the Masters of Dietetic Practice at La Trobe University in 2017, which will allow her to fulfil her goal of becoming a clinical dietitian. At present, Cassandra is in the final stages of preparing to submit her systematic review for publication. Cassandra’s areas of interest include: Mediterranean diet, cardiovascular disease, diabetes and obesity.