Trillions of living organisms exist in our gut. They were actually once thought to be harmful, but we now know that they are beneficial for our overall health and wellbeing. It was also believed that our digestive system was simply a long tube where food passes through, gets digested and then excreted. Today, we know it functions as much more than just a passage for food, it allows us to absorb nutrients and facilitates the removal of wastes, and helps to support many other body systems and functions including a healthy immune system and healthy mood balance.
Prebiotics vs probiotics
A combination of prebiotics and probiotics is important for building and maintaining a healthy colony of bacteria in the gut.
Prebiotics are a type of fibre that the human body does not digest or absorb, found in foods such as fruits, veggies and whole grains. Because they don’t get digested or absorbed, prebiotics are able to serve as a food source for beneficial bacteria (probiotics). Once they’ve been used as a food source, they break down and ferment to produce short-chain fatty acids, which are anti-inflammatory compounds that are crucial for colon health, energy metabolism and disease prevention.
Probiotics on the other hand are defined as live microorganisms that confer a health benefit on the host. They are living, beneficial bacteria that are found in fermented foods such as yoghurt and kombucha. They offer several benefits on the body, particularly in supporting digestive health and function. They modulate the microorganisms in our gut, helping to colonise more of the beneficial bacterial strains while exerting against pathogenic bacteria to prevent or limit their colonisation.
Probiotics also help to improve the physiological barrier function of the gut. They signal pathways that lead to the increase of the protective mucous layer that lines the digestive tract and on the proteins of tight junctions (tight junctions are formed by intestinal cells that limit water and food particles from escaping the intestines and into intracellular space).
The human gut is a huge and complex ecosystem where microorganisms, nutrients and cells interact with each other to maintain gut health and function. The trillions of diverse microorganisms that inhibit the gut are known as the intestinal microbiota, or microbiome.
The human microbiome is unofficially considered an ‘organ’ due to its great bacterial complexity. It plays many roles in the body including immune system development, defence against pathogens and influencing human behaviour and moods. Our microbiome is constantly changing and developing through factors like diet choices, stress and antibiotic use. A healthy human gut houses at least 1000 different species of bacteria, as well as some viruses and fungi.
Benefits of a healthy microbiome
Dysbiosis is the term used when your microbiome is out of balance, often caused by a variety of factors like diet, stress, genetics, antibiotics and other medications. Some common symptoms of dysbiosis are bloating, flatulence, constipation and/or diarrhoea. Having a healthy and balanced gut microbiome regulates and supports healthy digestive function, reducing unwanted symptoms like the ones mentioned above. Optimal digestion and thus a healthy gut microbiome is crucial for the proper removal of waste from the body.
Did you know that the health of our microbiome can impact our mood and mental wellbeing? There is a complex communication network between the gut and the brain – this is known as the gut-brain axis. We often unintentionally refer to the link between our gut and the brain by saying things like ‘gut instinct’ and ‘butterflies in the stomach.’ The gut-brain axis controls normal digestive function and also exerts effects that support mood and cognitive function. Emerging evidence supports dysbiosis and its impact on mood and behaviour.
Having a healthy balance of good bacteria in your gut is also important for immune system health. More than 70% of our immune cells are located in the gut, especially in the small intestine. Good bacteria help to stimulate immune cells like immunoglobulins and cytokines that support healthy immune responses in the body.
How to support your gut health
The diet is the leading source of energy for the growth of beneficial bacteria in the gut, so having a balanced and varied diet is key for maintaining a healthy digestive system. Enjoy a wide variety of fruit, vegetables and wholegrains, especially asparagus, Jerusalem artichoke, garlic, peas and beans – they are all rich in prebiotics. As for probiotics, they are found in fermented foods like yoghurt, kimchi, kombucha, sauerkraut and miso soup. Enjoying many of these foods in your diet helps support the growth and colonisation of beneficial bacteria in your gut.
You might like to consider taking a probiotic supplement if you find it difficult to add these foods into your diet. There are plenty of probiotic supplements on the market, so we recommend you consult your healthcare professional to help you choose the most suitable probiotic supplement for you.
If you have any questions or concerns about gut health, prebiotics or probiotics, we recommend speaking to your healthcare professional.
- Brown, M.J. (2016), How Short-Chain Fatty Acids Affect Health and Weight,
- Davani-Davaro, D. et al. (2019), Prebiotics: Definition, Types, Sources, Mechanisms and Clinical Applications, Foods 8(3):2
- Foster, J.A., Rinaman, L., Cryan, J.F. (2017), Stress & the gut-brain axis: Regulation by the microbiome, Neurobiology of Stress, 7: 124-136
- Hooks, K.B & o’Malley, M.A. (2017), Dysbiosis and its Discontents, American Society for Microbiology, 8(5): e01492-17