What is IBS?
Irritable Bowel Syndrome (IBS) is a common but complex digestive condition that affects how the gut functions, rather than its structure. That means routine tests often come back “normal”, even though the symptoms are very real and can be life-altering.
IBS is classed as a functional gut disorder. The gut itself is intact, but the way it moves, senses, communicates and responds is altered. This helps explain why IBS can be so frustrating to diagnose and treat, and why people are often told conflicting or dismissive things about it.
Symptoms can fluctuate over time and often include bloating, abdominal pain, altered bowel habits, urgency, fatigue and food sensitivities. Many people also experience anxiety, low mood or disrupted sleep alongside their gut symptoms, reflecting how closely the gut and nervous system are linked.
Crucially, IBS is not a diagnosis of exclusion meaning “nothing is wrong”. Modern research shows that IBS is associated with measurable changes in gut physiology, including altered microbial diversity, heightened nerve sensitivity in the gut, low-grade immune activation, changes in gut permeability, and disrupted signalling along the gut–brain axis.
IBS often develops after a trigger such as food poisoning, antibiotic use, prolonged stress, illness, or repeated restrictive dieting. In ecological terms, something disturbs the balance of the system. The gut becomes less resilient, more reactive, and slower to recover from everyday inputs like food, hormones or emotional stress.
How can microbes help?
How microbes help IBS is not just a question of relieving symptoms. It is a question of ecology and balance. Of how the human gut, much like soil, thrives when diversity is restored and stress is reduced.
Irritable Bowel Syndrome (IBS) affects at least 12% of the UK population. Yet for many, it remains poorly understood, under-supported and often dismissed as “just stress” or “something you have to live with”.
At microbz, we see IBS as a sign that the gut ecosystem is under pressure. Much like soil that has lost its microbial life, the gut can become less resilient when diversity is reduced and stress is high. The good news is that ecosystems are designed to recover.
This blog looks at the latest UK-led microbiome research, to explore how microbes help IBS, why stress plays such a powerful role, and what rebuilding a resilient gut ecosystem can look like in practice.
IBS is not “all in your head”, but it does involve the brain.
What actually happens with IBS?
IBS is classified as a functional gut disorder. That means symptoms occur without obvious structural damage, but very real dysfunction is happening beneath the surface. Common symptoms include:
• Bloating and excessive gas
• Abdominal pain or cramping
• Diarrhoea, constipation, or both
• Urgent or unpredictable bowel movements
• Food sensitivities
• Fatigue and low mood
What unites these symptoms is altered gut function, not imagination. Research increasingly shows that IBS involves changes in microbial diversity, low-grade inflammation, more sensitivity in gut nerves, and even leaks in the gut lining. IBS also upsets the normal regulation of the gut-brain axis which can lead to mood swings and fatigue.
Microbes sit at the centre of all this.
Why does microbial diversity matter in IBS?
A healthy gut is not dominated by one “good” microbe. It is a living ecosystem, a diverse, dynamic community of bacteria, yeasts and other microorganisms, each performing slightly different roles. Some break down fibres, some produce vitamins, some regulate immune responses, and others help keep potentially harmful microbes in check.
Studies from King’s College London and University of Nottingham consistently show that people with IBS tend to have reduced microbial diversity with fewer beneficial fermenting microbes. Instead, populations of gas-producing or inflammatory microbes can become more dominant.
This imbalance, often called dysbiosis, can lead to:
• Excess gas and bloating from poorly fermented fibres
• Irritation of the gut lining
• Increased sensitivity of gut nerves
• Disrupted immune signalling
In other words, the gut ecosystem loses its resilience. This is one of the key reasons microbes play such an important role in IBS.
How microbes help IBS symptoms
1. Microbes help regulate bowel movements
Certain microbes produce short-chain fatty acids (SCFAs) such as butyrate. These compounds nourish the gut lining and support regular bowel movements. Lower SCFA production has been linked to both diarrhoea-predominant and constipation-predominant IBS.
So restoring microbial activity helps restore rhythm.
2. Microbes calm gut inflammation
Although IBS is not classified as an inflammatory disease like Crohn’s, low-grade inflammation is increasingly recognised. Beneficial microbes help by interacting with immune cells in the gut lining and producing anti-inflammatory metabolites.
Research from NLM shows that certain microbial signals actively train the immune system to tolerate normal gut activity rather than over-react to it.
3. Microbes strengthen the gut barrier
Many people with IBS show increased intestinal permeability, sometimes referred to as “leaky gut”. When the gut barrier is damaged, food particles and bacterial fragments cross into the bloodstream, triggering immune responses and increasing pain.
Microbes help maintain the gut barrier by feeding the cells that line the gut, so keeping the gut barrier intact, and out-competing harmful bacteria for space and resources. A resilient barrier is quieter, calmer and less reactive.
IBS and the gut–brain axis
Why stress makes IBS worse
If you live with IBS, you already know stress and symptoms are linked. This is not coincidence. We know now that the gut and brain communicate constantly via the vagus nerve.
Chronic stress alters this communication ‘superhighway’. Studies from University of Oxford show that stress hormones can alter bowel movements, increase gut permeability, and change your microbial composition.
At the same time, microbes influence how the brain perceives stress by producing neurotransmitter messengers such as serotonin and GABA.
IBS is rarely caused by stress alone. But stress can tip an already vulnerable ecosystem into imbalance. Supporting microbes therefore supports both the gut and the nervous system.
IBS and the gut-brain axis diagram
Why one-size-fits-all probiotics often fail in IBS
Many people with IBS have tried probiotics with mixed results. Some help. Some make symptoms worse. This is because IBS is not a single condition and each microbiome is unique, so introducing the wrong strains at the wrong time can increase gas or discomfort.
Research increasingly supports the idea of adaptive, ecosystem-focused microbial support, rather than an aggressive high-dose, single-strain approach that can overwhelm a sensitive gut. Living, diverse microbial products that work with the body and rebalance the gut, rather than override it, align more closely with how biological systems naturally recover.
This mirrors what we see in soil: diversity and balance restore function more effectively than monoculture inputs.
IBS as an ecological issue, not a personal failing
At microbz, our soil-to-stomach philosophy is not metaphorical. It is biological.
Healthy soils are microbially diverse, they are more resilient to and recover faster from stresses from weather or disease, and they cycle nutrients more efficiently.
Healthy guts do the same. IBS often develops after antibiotic use, food poisoning, chronic stress, or repeated restricted dieting. All of these reduce diversity. Supporting IBS means rebuilding the ecology of the gut, not fighting the body.
Practical ways to support microbes if you have IBS
1. Feed microbes gently
Highly restrictive diets may reduce symptoms short term but starve microbes long term. Where tolerated, gradually reintroduce diverse plant fibres, polyphenol-rich food, and fermented foods that will support microbial recovery.
2. Support stress regulation
Microbes respond to nervous system signals. Practicing breathing exercises, spending time outdoors, getting regular sleep and taking gentle exercise directly influence microbial balance via the gut–brain axis.
3. Choose microbial support that respects sensitivity
For IBS, less aggressive approaches often work better. Go for living, liquid microbes rather than isolated high-dose powders. Look for diverse communities rather than single strains of microbes. Embrace change consistently rather than in short sharp bursts, because that works best to reduce the risk of symptoms flaring up and supports long-term balance.
Where microbz fits into IBS support
Microbz products are designed to:
• Support microbial diversity
• Work adaptively with the body
• Be gentle enough for sensitive systems
Many customers with IBS choose to start slowly, listening to their body, rather than forcing change. You can explore our revive gut health product and our wider gut support range online, where we share education alongside products.
IBS, microbes and hope
IBS can feel isolating, unpredictable and exhausting. But the science is shifting.
Microbiome research now recognises that IBS is real, that microbes play a central role, and that the gut ecosystem has an extraordinary capacity to recover.
Supporting microbes is not about fixing a broken body. It is about restoring trust in an internal ecology that is designed to adapt and thrive.
References and further reading
King’s College London (2024) Gut health and diet, King’s College London. Available at: https://www.kcl.ac.uk/research/gut-health-and-diet (Accessed: 11 February 2026).
University of Nottingham (2024) New research could lead to genetically tailored diets to treat patients with IBS, University of Nottingham. Available at: https://www.nottingham.ac.uk/news/new-research-could-lead-to-genetically-tailored-diets-to-treat-patients-with-ibs (Accessed: 11 February 2026).
Wang, Q., Meng, Q., Chen, Y., Liu, Y., Li, X., Zhou, J., Ma, Y., Yu, Z. and Chen, X. (2025) ‘Interaction between gut microbiota and immunity in health and intestinal disease’, Frontiers in Immunology, 16, Article 1673852. Available at: https://pmc.ncbi.nlm.nih.gov/articles/PMC12641010/ (Accessed: 11 February 2026).
University of Oxford (2018) Can microbes manipulate our minds?, University of Oxford. Available at: https://www.ox.ac.uk/news/2018-04-26-can-microbes-manipulate-our-minds (Accessed: 11 February 2026).
Vasant, D., Paine, P., Black, C., Houghton, L. A., Everitt, H., Corsetti, M., Aggarwal, A., Aziz, I., Farmer, A. D., Eugenicos, M. P., Moss-Morris, R., Yiannakou, Y. and Ford, A. C. (2021) British Society of Gastroenterology guidelines on the management of irritable bowel syndrome, Gut, 70(7), pp. 1214–1240. Available at: https://doi.org/10.1136/gutjnl-2021-324598 (Accessed: 11 February 2026).
Collins, S. M. (2014) ‘A role for the gut microbiota in IBS’, Nature Reviews Gastroenterology & Hepatology, 11, pp. 497–505. Available at: https://www.nature.com/articles/nrgastro.2014.40 (Accessed: 11 February 2026).
Soubieres, A., Wilson, P., Poullis, A., Wilkins, J. and Rance, M. (2015) Burden of irritable bowel syndrome in an increasingly cost-aware National Health Service, Frontline Gastroenterology, 6(4), pp. 246–251. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5369587/ (Accessed: 11 February 2026).
This article reflects the latest available research. As new studies emerge, this blog will be updated and republished to reflect current understanding.
