Did you know that you have more bacterial than human cells? It might sound shocking, but it's true. We’re composed of 10 times more bacterial cells than human cells. Most of these microbes are not only harmless, but essential to our wellbeing. They play a huge role in digestion, immunity, mood, and even skin and vaginal health.
In this blog post, we’ll break down the big three: prebiotics, probiotics, and postbiotics. You'll learn what they are, how they work, and how to support your microbiome to feel your best - especially if you’re managing a sensitive gut or conditions like IBS.
The colonic microbiome: your inner ecosystem
Over 70% of your body’s bacteria live in the large intestine, creating what's known as the colonic microbiome. This community of around 100 trillion microbes (weighing roughly 200g!) is vital for maintaining health. These beneficial bacteria help:
Break down fibre and resistant starch
Protect against harmful bacteria
Support the immune system
Produce vitamins and anti-inflammatory compounds
However, the balance of this internal ecosystem can be easily disrupted.
What can disrupt gut bacteria?
Several factors can reduce the number or diversity of beneficial bacteria in the colon, including:
Food poisoning or gastroenteritis
Broad-spectrum antibiotics that wipe out both good and bad bacteria
Stress, which alters bowel function and immune response
Ageing
Restrictive diets like the Low FODMAP diet, if followed too long without reintroduction
Diets high in fat or alcohol, which promote harmful bacteria
People with Irritable Bowel Syndrome (IBS) often have lower levels of beneficial bacteria, especially after infections, antibiotic use, or frequent diarrhoea.
Probiotics: the friendly bacteria
Probiotics are live microorganisms that may offer health benefits when consumed in adequate amounts. These are typically the same types of bacteria naturally found in the gut, such as Lactobacillus and Bifidobacterium species.
What does the research say?
According to the British Dietetic Association (BDA), probiotics may help some people with IBS, but the evidence is inconsistent. This is because different probiotic strains have different properties, there are individual variations in gut bacteria and varying symptoms of IBS.
If you’d like to try a probiotic, make sure you try one which is clinically studied and is strain and species-specific. It’s also important to choose one which is proven to reach the gut alive, is allergen-free and is shelf-stable, such as Alflorex®.
Prebiotics: food for your good bacteria
While probiotics are live bacteria, prebiotics are the fibres that feed them. These include inulin, fructo-oligosaccharides (FOS), and galacto-oligosaccharides (GOS), naturally found in:
Onions and garlic
Chicory root
Artichokes
Lentils, beans, and chickpeas
Whole grains like wheat and oats
By feeding the beneficial bacteria in your gut, prebiotics help increase their numbers and support long-term microbiome health.
Prebiotics and IBS
The catch? Most prebiotics are also high in FODMAPs - fermentable fibres that can trigger symptoms like gas, bloating, and diarrhoea in people with IBS.
This is why the Low FODMAP diet works by temporarily removing these foods. However, staying on this restrictive diet for too long may decrease beneficial bacteria, particularly bifidobacteria. Reintroduction of prebiotic-rich foods is essential after the 4–8 week exclusion phase to maintain a balanced gut microbiome.
Postbiotics: the next big thing?
You’ve heard of probiotics and prebiotics - but what about postbiotics? Postbiotics are the beneficial compounds produced when bacteria digest fibre (a result of probiotics and prebiotics together). These include:
Short-chain fatty acids (SCFAs) like butyrate, propionate, and acetate
Bacterial cell wall fragments
Enzymes and peptides
These compounds can reduce inflammation, support gut lining integrity, and modulate the immune system. Some researchers believe that the benefits of probiotics may actually come from the postbiotics they produce - not the live bacteria themselves. Postbiotics are an emerging area of study, with growing interest in creating supplements or functional foods that deliver these health-promoting molecules directly, without needing live bacteria.
Taking a balanced approach to supporting your gut microbiome
When it comes to supporting gut health, a balanced approach works best. Here’s how to nurture your microbiome naturally.
Eat a fibre-rich diet Include a variety of plant-based foods to feed your gut bacteria. Think vegetables, legumes, fruits, whole grains, and nuts.
Try a quality probiotic If you have digestive issues or are recovering from antibiotics, a well-researched probiotic might help restore balance.
Include prebiotics with care Reintroduce prebiotic foods slowly if you’re sensitive. Cooked onions or bananas are good low-FODMAP starting points.
Manage stress Chronic stress alters gut function and reduces bacterial diversity. Mindfulness, regular sleep, and movement can all help.
Limit processed foods Excessive sugar, fat, and alcohol feed harmful bacteria and damage your gut lining.
Your gut bacteria are crucial to more than just digestion - they influence your immune system, energy, mood, and vaginal health too. While the world of prebiotics, probiotics, and postbiotics can be complex, the takeaway is simple: nurture your gut, and it will nurture you.
Whether you're dealing with IBS, looking to boost your digestion, or just want to support long-term health, understanding how to support your microbiome is a smart step forward.
