Symptoms and conditions
Gut inflammation and its role in chronic disease
Long-term, low-grade inflammation throughout the body is linked with heart disease, type 2 diabetes, fatty liver and some cancers. The gut contributes to it through the state of its lining, the balance of its bacteria and the food it receives. Some of these links are firmly established, and others are still being studied. The measures that lower inflammation are well known and available to everyone.
In short
- Acute inflammation is a healthy, short-lived response. Chronic low-grade inflammation is a persistent, quiet activation of the immune system.
- It is driven largely by weight around the waist, inactivity, poor sleep, smoking and diet.
- The gut is one source: a damaged lining and a depleted population of bacteria allow more inflammatory signals into the blood.
- Some gut conditions have proven long-term consequences elsewhere. Many other claimed links are not yet proven.
What is chronic low-grade inflammation?
When you cut a finger, the immune system responds for a few days and then stands down. In chronic inflammation it never fully stands down. There is no pain or fever. It is detected only by slightly raised markers in the blood, and over years it contributes to damage in blood vessels, the liver and other organs.
How does the gut contribute?
The gut lining
A healthy lining keeps bacteria and their products inside the gut. When it is more permeable, more of this material reaches the liver and the bloodstream and stimulates the immune system. See the gut lining.
Gut bacteria
Bacteria that ferment fibre produce short-chain fatty acids, which calm immune activity. A low-fibre diet reduces these bacteria.
What we eat
Diets high in refined sugar, processed food and alcohol, and low in plants, are associated with higher inflammatory markers.
Fat inside the abdomen
Fat around the organs releases inflammatory substances directly into the blood flowing to the liver.
Which links are well established?
| Gut condition | Long-term consequence |
|---|---|
| Long-standing colitis | Higher risk of bowel cancer, reduced by good control and surveillance |
| H. pylori gastritis | Higher risk of stomach ulcers and stomach cancer, reduced by treatment |
| Untreated coeliac disease | Anaemia, weak bones and, rarely, lymphoma of the intestine |
| Fatty liver with inflammation | Liver scarring, and a higher risk of heart disease |
| Chronic reflux | Barrett’s change in the food pipe |
In each of these, treating the gut condition lowers the later risk.
Which links are still uncertain?
Research connects the gut with depression, Parkinson’s disease, arthritis, allergies and skin disease. In most of this work it is not yet clear whether the gut changes are a cause, a consequence or a companion of the illness. It is reasonable to look after the gut for its own sake. It is not reasonable to expect that doing so will treat these conditions.
What lowers chronic inflammation?
Reduce weight around the waist
Even a modest loss lowers inflammatory markers.
Move every day
Regular exercise has a direct anti-inflammatory effect, independent of weight.
Eat mostly plants and whole foods
Vegetables, fruit, pulses, whole grains, nuts and fish, with less sugar, refined flour and processed meat. In one trial, a diet rich in fermented foods lowered several markers of inflammation.
Sleep seven to eight hours
Short sleep raises inflammatory markers.
Stop smoking, and limit alcohol
Both drive inflammation in the gut and beyond.
Treat the gut conditions you have
Reflux, H. pylori, coeliac disease, colitis and fatty liver, each properly.
Should I have my inflammation tested?
A blood marker of inflammation is useful to a doctor in the right setting. It is not a screening test for general health, and a single raised value has many possible explanations, including a recent cold. I measure it when the result would change what we do.
When should I see a doctor?
See a doctor for persistent gut symptoms, and for the checks that find silent conditions: blood sugar, cholesterol, liver tests and, from about 45, bowel cancer screening.
Questions patients ask me
Is there an anti-inflammatory diet?
There is no single one. The patterns with the most evidence are rich in vegetables, fruit, pulses, whole grains, nuts and fish, and low in processed food. A traditional home-cooked Indian diet with plenty of vegetables and pulses fits this well.
Do turmeric and other supplements reduce inflammation?
Turmeric in cooking is a healthy habit. Concentrated supplements have not been shown to prevent chronic disease, and some have caused liver injury. Food, movement and sleep have far more evidence.
Can I feel chronic inflammation?
Usually not. It causes no specific symptoms, which is why its drivers, such as waist size, blood sugar and blood pressure, are worth measuring.
Sources
This page is written for patients and is based on the guidelines and studies below. It is for education and does not replace a consultation.
- Review of chronic inflammation in disease across the life span. Furman D et al. Nat Med. 2019. PubMed 31806905
- Review of the gut-liver axis and the microbiome. Tripathi A et al. Nat Rev Gastroenterol Hepatol. 2018. PubMed 29748586
- Review of the microbiota in immunity and inflammation. Belkaid Y, Hand TW. Cell. 2014. PubMed 24679531
- Review of intestinal permeability: mechanisms, measurement and clinical implications. Camilleri M. Gut. 2019. PubMed 31076401
- Trial of high-fibre and fermented-food diets and immune status. Wastyk HC et al. Cell. 2021. PubMed 34256014