That Gut Feeling: Why Prebiotics, Probiotics and Postbiotics Matter

So you want to support your microbiome, but what exactly are prebiotics, probiotics and postbiotics? Where can you find them and what will they do for you?

The gut microbiome has become one of the most exciting areas of health research in recent years.  Scientists are continually discovering how the trillions of microorganisms living in our digestive tract influence many aspects of our wellbeing, from digestion and immune function to mood and metabolic health.  Supporting a diverse and balanced microbiome is an important part of maintaining overall health. 

Prebiotics are types of fibre and plant compounds that feed beneficial bacteria in the gut.  They are not digested by us, but instead act as fuel for our microbes, helping them multiply and thrive. Foods rich in prebiotics include onions, garlic, leeks, asparagus, oats and legumes.  By nourishing beneficial bacteria, prebiotics help create the right environment for a healthy microbiome and support the production of important compounds that benefit overall health.

Probiotics are beneficial live microorganisms that can support the balance of bacteria in the gut. These are found naturally in fermented foods.  Probiotics work by helping to replenish helpful bacteria, crowding out less beneficial microbes, and producing compounds that support the health of the gut lining.  Regularly consuming probiotic foods may help improve digestion, support immune function, and contribute to a more diverse gut microbiome.

Beyond probiotics, there is growing interest in postbiotics, which are the beneficial compounds produced by microbes as they ferment food in our gut.  Postbiotics include a wide range of bioactive substances, but among the most important are short-chain fatty a

cids (SCFAs) such as acetate, propionate and butyrate.  These compounds help to nourish the cells lining the colon, regulate inflammation, and play a key role in metabolic health, including blood glucose balance, appetite regulation and lipid metabolism.  They also act as signalling molecules, allowing the gut microbiome to communicate with other systems in the body.  That’s right!  Your gut is actually talking to the rest of your body and may influence things like mood, cognition, energy, metabolism and immunity.

Fermented foods are particularly valuable because they contribute to this process in multiple ways. They provide probiotics directly, and they also support the production of beneficial postbiotics in the gut.

Some well-known fermented foods include:

Kimchi is a traditional Korean dish made from fermented vegetables, commonly cabbage and radish, combined with garlic, ginger and chilli. It is rich in lactic acid bacteria, which are known to support microbial diversity in the gut.

Sauerkraut is a classic fermented cabbage dish originating from Central and Eastern Europe. When made traditionally with just cabbage and salt, it becomes rich in beneficial bacteria during fermentation.

Fermented lemons are often used in North African and Middle Eastern cooking. Preserved in salt and their own juices, they undergo natural fermentation and develop both a distinctive flavour and beneficial microbes.

Kefir is a fermented milk drink made using kefir grains, which contain a unique combination of bacteria and yeasts. It is one of the most diverse probiotic foods and may help support both digestion and gut microbial balance.

Adding small amounts of fermented foods regularly to meals can be a simple way to introduce beneficial microbes into the diet. It is best to start slowly, especially for those new to fermented foods.

Supporting the microbiome does not rely on just one food or supplement. A varied, fibre-rich diet that includes both prebiotic plant foods and fermented foods can help nourish beneficial bacteria and support the production of health-promoting compounds within the gut.

Practical tips: how to support your gut at home

If you are new to fermented foods, a gradual approach is often best:

Start with 1 to 2 teaspoons of sauerkraut or kimchi alongside a meal and build up slowly

Choose unpasteurised products where possible, as these contain live bacteria

Pair fermented foods with prebiotic-rich foods such as oats, onions or lentils to support bacterial growth

Consistency is key. Small amounts eaten regularly are often more beneficial than large amounts eaten occasionally. Over time, these simple additions can help support a more resilient and diverse gut microbiome.

References

Gibson, G.R. et al. (2022) ‘The concept of prebiotics: revisited and updated’, Nature Reviews Gastroenterology & Hepatology, 19(8), pp. 491–502.

Hill, C. et al. (2023) ‘Expert consensus document: The International Scientific Association for Probiotics and Prebiotics (ISAPP) on the definition and scope of probiotics’, Nature Reviews Gastroenterology & Hepatology, 20, pp. 15–27.

Mann, E.R., Lam, Y.K. and Uhlig, H.H. (2024) ‘Short-chain fatty acids: linking diet, the microbiome and immunity’, Nature Reviews Immunology, 24, pp. 577–595.