We talk a lot about what we should remove from our diets. Ideally we would be eating less sugar, less ultra-processed food, less stress eating and less alcohol. But sometimes health is not just about what we take away. Most of the time it is about what we add back in.
One of the most overlooked things we can add back into modern life is diversity. The advice is that we should be looking at eating 30 different plants a week with diverse fibers and diverse microbes in them. This is where prebiotics come in.
As conversations around gut health continue to grow, words like “probiotic” and “microbiome” are becoming more familiar. But prebiotics are still often misunderstood, even though they may be one of the most important foundations for long-term gut health.
At microbz, we think of the gut a bit like a garden. Probiotics are the seeds. They introduce beneficial living microbes into the ecosystem. Prebiotics are the nourishment. They are the fibres and compounds that help those microbes thrive. Without nourishment, even the best seeds struggle to grow.
What are prebiotics?
Prebiotics are naturally occurring fibres and plant compounds that feed beneficial microbes in the gut. Unlike many other foods, prebiotics are not broken down and absorbed in the upper digestive tract. Instead, they travel through the stomach and small intestine largely intact until they reach the colon, where trillions of microbes begin fermenting them. This fermentation process matters more than most people realise.
When microbes ferment prebiotic fibres, they produce compounds called short-chain fatty acids, including butyrate, acetate and propionate. These compounds help maintain the gut lining, support immune function, regulate inflammation and influence metabolism.
Researchers are now uncovering connections between these microbial metabolites and everything from mood and cognition to blood sugar regulation and cardiovascular health.
In other words, we are not just feeding ourselves when we eat fibre-rich foods. We are feeding an ecosystem inside us. The microbial ecosystem inside us helps shape our health every single day.
The modern fibre problem
For years, the nutrition conversation focused heavily on quantity. How many grams of fibre are you eating? Newer research suggests quality and diversity matter too.
Traditional diets across the world naturally contained dozens of different plant fibres every week. Modern diets often contain only a fraction of that diversity. Even people trying to “eat healthy” can end up eating the same few foods repeatedly. The microbes in the gut respond to this loss of diversity.
A landmark 2021 study published in Cell found that people consuming a more diverse, fibre-rich diet showed measurable improvements in microbiome function and immune markers. Other large-scale studies have consistently linked higher plant diversity intake with greater microbial diversity, which is associated with resilience and better long-term health outcomes.
This is one reason why many researchers are moving away from simplistic conversations around calories and macronutrients and towards a broader ecological view of nutrition.
The question is no longer just: “What are we feeding ourselves?” It is also: “What are we feeding our microbes?”
Why prebiotics matter for health
The gut is deeply connected to almost every system in the body. The microbes living there interact constantly with the immune system, nervous system, hormones and metabolism. This means supporting beneficial bacteria through prebiotic foods may influence far more than digestion alone.
Emerging evidence suggests prebiotic-rich diets may help support:
· digestive regularity
· gut lining integrity
· immune resilience
· calcium absorption
· cholesterol metabolism
· blood sugar balance
· hormonal health
· inflammatory regulation
· mood and cognitive function
The gut-brain connection is one of the most fascinating areas of modern science. Researchers are increasingly exploring how microbial fermentation products influence neurotransmitters, stress responses and inflammation within the nervous system.
There is still a huge amount we do not yet understand. But what is becoming clear is that the health of the microbiome appears closely tied to the health of the whole person.
Prebiotics and probiotics: what is the difference?
The two words sound similar because they work together.
A probiotic is a living microorganism that may support health when consumed in adequate amounts.
A prebiotic is the nourishment that helps beneficial microbes survive and flourish.
You can think of probiotics as introducing life into the system, while prebiotics help sustain and strengthen that life over time.
Nature doesn’t work in isolation. Microbes do not exist alone, they live in communities where they communicate, cooperate and compete. In a healthy ecosystem diversity creates resilience. Also, microbes are great communicators and they need to work in collaboration with prebiotics and herbs and minerals to help create bio-availability in systems.
The best prebiotic foods
One of the beautiful things about prebiotics is that they are not exotic. Most are simple, everyday foods. Many traditional diets naturally contained large amounts of prebiotic fibres long before the word “microbiome” existed.
Some of the richest prebiotic foods include:
Apples: rich in pectin, a fibre linked to beneficial gut bacteria and microbial diversity.
Garlic and onions: excellent sources of inulin and fructooligosaccharides which help feed beneficial microbes.
Leeks and asparagus: contain fibres that support fermentation and microbial activity in the colon.
Oats and barley: rich in beta-glucans which may support cholesterol balance and gut health.
Bananas: especially when slightly green, bananas contain resistant starch that acts as a prebiotic.
Flaxseeds: contain both fibre and polyphenols that support microbial activity and digestive health.
Legumes: beans, lentils and chickpeas provide diverse fermentable fibres that nourish gut bacteria.
Cocoa: pure cocoa contains polyphenols that beneficial microbes can metabolise into bioactive compounds.
Sweet potatoes: contain resistant starches and fibres that support microbial fermentation.
Different microbes feed on different fibres. The wider the variety of plant foods we consume, the wider the range of microbes we are likely to support.
The forgotten relationship between humans and microbes
For most of human history, we lived much closer to nature than we do today. We ate seasonal foods grown in living soil. We touched plants, animals and earth daily. We consumed naturally fermented foods regularly without labelling them as “functional”.
Modern life has brought many extraordinary advances, but it has also reduced our exposure to microbial diversity. Ultra-processed diets, over-sanitised environments, chronic stress and reduced contact with nature may all be influencing the ecosystems within us.
This does not mean modern life is bad, but it may mean that some of the oldest relationships in human biology matter more than we realised.
Simple ways to increase prebiotics naturally
Supporting your microbiome does not need to become another complicated wellness routine. Often, small consistent changes matter most.
You could begin by:
· adding an extra plant food to meals each week
· eating more legumes and whole grains
· including garlic, onions or leeks in cooking
· swapping processed snacks for fruit, nuts or oats
· eating a wider variety of seasonal foods
· combining prebiotic foods with fermented foods and probiotics
The goal is creating conditions where beneficial microbes can flourish, because when the microbial ecosystem becomes healthier and more diverse, the effects can ripple through the whole body.
Eat your way to a happier gut: recipes we love
Eating for your gut doesn't have to be complicated. Here are three recipes that pack in prebiotic ingredients without sacrificing any of the flavour:
Prebiotic superfood stew by the happy pear: a warming, seasonal stew packed with tomatoes, lentils, beans, and sweet potato. A brilliant example of eating well with what's in season.
Chocolate and walnut banana bread baked oats: a fantastic way to enjoy oats, full of healthy fats and fibre. Great as a weekend breakfast or a prep-ahead weekday option.
Vegan skillet apple oat crumb cake: packed with fibre and protein, this puts a gut-friendly spin on a classic pudding.
References
Cryan, J.F. et al. (2019) ‘The microbiota-gut-brain axis’, Physiological Reviews, 99(4), pp. 1877–2013.
Gibson, G.R. et al. (2017) ‘The concept of synbiotics and its role in gut health’, Nature Reviews Gastroenterology & Hepatology, 14(8), pp. 491–502.
Hill, C. et al. (2014) ‘Expert consensus document: The International Scientific Association for Probiotics and Prebiotics consensus statement on the scope and appropriate use of the term probiotic’, Nature Reviews Gastroenterology & Hepatology, 11, pp. 506–514.
Oliver, A. et al. (2021) ‘High-fiber, whole-food dietary intervention alters the human gut microbiome’, mSystems, 6(1), e00115-21.
Sanders, M.E. et al. (2018) ‘Probiotics and prebiotics in intestinal health and disease’, Gastroenterology Clinics of North America, 46(1), pp. 1–17.
Silva, Y.P., Bernardi, A. and Frozza, R.L. (2020) ‘The role of short-chain fatty acids from gut microbiota in gut-brain communication’, Frontiers in Endocrinology, 11, p. 25.
Vinelli, V. et al. (2022) ‘Effects of dietary fibers on short-chain fatty acids and gut microbiota composition in healthy adults: A systematic review’, Nutrients, 14(13), p. 2559.
Wang, L.Y. et al. (2024) ‘Short-chain fatty acids: bridges between diet, gut microbiota, and host health’, Clinical Nutrition, 43(6), pp. 1234–1248.
Visuthranukul, C. et al. (2024) ‘Enhancing gut microbiota and microbial function with inulin supplementation’, International Journal of Obesity, 48, pp. 1021–1032.
Zmora, N., Zeevi, D., Korem, T., Segal, E. and Elinav, E. (2016) ‘Taking it personally: personalized utilization of the human microbiome in health and disease’, Cell Host & Microbe, 19(1), pp. 12–20.
