What if one of the biggest drivers of your pain isn't in your back or your knee—but in your gut?

It sounds surprising, but research over the past decade suggests exactly that. Scientists are increasingly discovering that the bacteria living inside our intestines influence inflammation, immunity and even how sensitive our nervous system becomes to pain.

The good news? One of the simplest ways to support those bacteria is something most of us aren't eating enough of: fibre and fermented foods.

Let me explain the link between your own gut health, chronic pain and what you can do today to start helping relieve your pain.

Our gut (yours included) is its own ecosystem living inside of you - fibre is the main source of food for the gut bacteria and only 4% of UK adults consume the recommended 30g of fibre daily (Cooper, 2025).

Foods that contain soluble, fermentable fibre are taken into the body and the gut where they are digested by microbes in the gut.

The bacterial colonies in your gut ferment fibre and create short chain fatty acids (SCFAs) - acetate, propionate and butyrate – or from dietary or endogenous proteins, such as mucous and sloughed epithelial cells (Du et al., 2024).

These acids determine gut microbiome and host physiology.

So why gut health matter if you have chronic back or joint pain?

Lack of fibre, antibiotic use, or high processed food intake impacts our microbiome diversity and can lead to gut dysbiosis.

This is characterised by a decrease in microbial diversity, reduced good bacteria and increases in harmful bacteria (ref) and the consequences are wide ranging (Shen et al., 2025):

·       Immune dysregulation including changing the profile of T-cell differentiation which leads to immune hypersensitivity and inflammation

·       Changes in the cell function of the nervous system and impaired regeneration and growth of certain cells of the nervous system

·       Increased gut permeability leading to endotoxemia (toxins leaking into the blood stream)

·       Chronic low grade systemic inflammation

·       Bacterial translocation (bacteria escape from the gut and into the body and tissues!

It is unsurprising then that gut dysbiosis is now being linked as a cause across many chronic pain conditions including the development of low back pain and osteoarthritis of joints (Su et al., 2023; Wei et al., 2026).

Building on the research in both areas over the last 10 years, gut health impacts pain through three main ways.

1.       Leaky gut from intestinal permeability secondary to localised intestinal inflammation allows bacteria and their metabolites to sneak out through the gut walls and into the body via the blood stream.

These bacteria can get into joints like the knee or hip and the lumbar discs (Ratna et al., 2023) and cause significant inflammation and structural damage over time, often leading to an imbalance of activity of bone regeneration and catabolism. This imbalance further perpetuates localised pro-inflammatory pathways and further joint destruction.

2.       The gut hosts many immune-related cells in the gut lining and hormonal receptors.

Gut dysbiosis regulates local intestinal and systemic immunity and hormonal signalling pathways. Changes in permeability and ‘leaky gut’ then lead to neuroinflammation, collectively forming a gut-brain-joint axis (Wei et al., 2026).

Neuroinflammation has a causal role in nearly all pain conditions because of the aberrant sensitisation of the peripheral and central nervous system.

3.       In the spine there may also be possible localised adaptive immune cell profiling

The spinal bone marrow is a rich source of immune cells and the increasing pro-inflammatory state in the body (and the blood) due to gut dysbiosis may result in localised immune changes in the marrow that may then impact surrounding structures via immune-modulatory pathways (Li et al., 2024).

It would appear then that osteoarthritis and low back pain share a causal mechanism of altered intestinal microbiome that shifts the body into a pro-inflammatory, immune-hypersensitive state.

Given the systemic effects of dysbiosis I would hazard an educated guess that this is possibly linked to most chronic joint pain conditions as we cannot escape the notion that chronic low-grade inflammation and immune hypersensitivity impact every tissue and all nociceptive free nerve endings in the body.

How to improve your gut health – and possibly your back and knee pain!

Short chain fatty acids directly inhibit proinflammatory pathways (Du et al., 2024) and control the actions of neutrophils, macrophages, dendritic cells, T cells and B cells, causing them to release less cytokines and pro-inflammatory molecules (Du et al., 2024).

Akkermansia is a bacterium in the gut that is emerging as a key player in SCFA synthesis and the deficiency of which leads to the downstream consequences described above.

Fibre is needed for gut health.

Dietary fibre encompasses a diverse set of plant-derived compounds, including but not limited to carbohydrates, that resist digestion by human enzymes and are associated with health-promoting effects.

The definition of dietary fibre is contested and varies depending on who you read but a recent review proposes that a working definition of fibre is the components of plant-based foods that contain varying chemical structures that are non-digestible in the small intestine (Goñi et al., 2026).

The easiest way to remember high fibre sources are BBGS which translates to… Beans, Berries, Seeds, Greens and Nuts (Nutrition.org).

Having a port of these with at least 2 meals per day will help feed your gut the right stuff it needs to develop a diverse, healthy bacterial colony and maximise your SCFA production!

It also seems that incorporating fermented food may have benefit for everyone – these are foods that contain live bacterial colonies.

Human trials show increases in gut diversity following regular consumption of fermented foods although it is unclear whether this is due to the new introduction of microbes, the metabolites (like SCFAs) present in the fermented foods – or other yet discovered mechanisms (Leeuwendaal et al., 2022).

The combination of regular fermented foods and daily fibre above and beyond the recommended UK guidelines for fibre intake will improve gut health and, given the causal pathways described above, help relieve symptoms associated with chronic low back or knee pain.

At least in knee osteoarthritis this appears to be true – high dietary fibre intake above the recommended daily guidelines led to reduced moderate-to-severe knee pain over an 8-year period in > 8000 people with knee osteoarthritis (Dai et al., 2017).

If you have persistent back pain or knee pain and you want a physiotherapist that looks at the person as a whole – not just the painful area – then click the book now button below to secure your physiotherapy assessment today!