Glossary · Dysbiosis and disease
Low-grade inflammation
In one sentence
Low-grade inflammation is a mild, persistent, systemic inflammatory activation with no acute infection or injury to explain it. It is detected through modest rises in markers such as high-sensitivity CRP.
Also known as: chronic low-grade inflammation · systemic low-grade inflammation · silent inflammation · inflammaging · metaflammation
What is low-grade inflammation?
Acute inflammation is a useful, time-limited response: it follows an infection or injury and then settles. Low-grade inflammation is different. It is systemic, mild and persistent, with no obvious acute trigger.
A 2019 Perspective in Nature Medicine by Furman and colleagues links systemic chronic inflammation with cardiovascular disease, cancer, diabetes, chronic kidney disease, non-alcoholic fatty liver disease, and autoimmune and neurodegenerative disorders. Risk factors it highlights include chronic infections, physical inactivity, poor diet, environmental toxicants and psychological stress. When the process is tied to ageing it is called inflammaging, a concept introduced by Franceschi and colleagues in 2000; when tied to obesity and metabolism, it is often called metaflammation.
How it is measured
There is no single test. The most widely used marker is high-sensitivity C-reactive protein (hs-CRP). The 2003 AHA/CDC scientific statement (Pearson et al., Circulation) proposed these bands for cardiovascular risk assessment:
- Below 1 mg/L: lower risk.
- 1 to 3 mg/L: average risk.
- Above 3 mg/L: higher risk.
Values above 10 mg/L point to an acute inflammatory process rather than low-grade inflammation, and the test is usually repeated. Other biomarkers studied include interleukin-6, TNF-α and fibrinogen, which are less used in routine practice. Reference ranges can vary between laboratories.
The gut connection
One of the most studied hypotheses links dysbiosis with increased intestinal permeability: bacterial components such as lipopolysaccharide (LPS) crossing into the circulation could activate the immune system. Cani and colleagues described this “metabolic endotoxaemia” in 2007 in mice fed a high-fat diet. In people, the evidence is mostly associative. Meanwhile, short-chain fatty acids produced by the microbiota have documented anti-inflammatory effects on the gut lining.
Low-grade systemic inflammation should be distinguished from local gut inflammation, which is assessed with markers such as faecal calprotectin.
Example
A physician reviews a patient with central obesity and prediabetes. hs-CRP is 4 mg/L on two measurements taken a fortnight apart, with no sign of infection. She interprets this as a possible low-grade inflammatory state related to the metabolic profile and prioritises weight, physical activity and diet, with repeat bloods at follow-up.
Low-grade inflammation at Xenogene
Xenogene does not offer a dedicated test for systemic inflammation. It does study factors that the literature links to it along the gut axis: microbiota composition, short-chain fatty acid metabolomics, calprotectin and zonulin as accessory data. The integrated profiles bring these results together, and interpretation always rests with the healthcare professional who requests them.
Frequently asked questions
What are the symptoms of chronic low-grade inflammation?
Usually none that are specific, which is why it is sometimes called silent inflammation. It is suspected from the clinical context and confirmed with blood tests, not symptoms. Tiredness or vague aches have many other possible causes.
Which blood test shows chronic inflammation?
The most widely used is high-sensitivity C-reactive protein (hs-CRP), sometimes alongside markers such as interleukin-6 or fibrinogen. No single marker is enough; the healthcare professional interprets results together with the clinical history.
Is gut health linked to low-grade inflammation?
Research connects them, mainly through the intestinal barrier and bacterial products that may reach the bloodstream. Much of the mechanistic evidence comes from animal models, while human data are largely associative.
Related terms
- Dysbiosis
Dysbiosis is a change in the composition or function of the microbiota away from what is considered compatible with health: loss of diversity, loss of beneficial microbes or overgrowth of others.
- Intestinal permeability
Intestinal permeability is how easily substances in the gut lumen cross the intestinal lining into the bloodstream. It is a normal, regulated property; increased permeability is associated with several diseases.
- Biomarker
A biomarker is a characteristic that is objectively measured and evaluated as an indicator of normal biological processes, disease processes or responses to a therapeutic intervention. It may be a molecule, a genetic variant or an imaging finding.
- Faecal calprotectin
Faecal calprotectin is a neutrophil protein measured in stool as a marker of inflammation of the intestinal lining. It helps distinguish inflammatory bowel disease from functional disorders such as irritable bowel syndrome.
- Short-chain fatty acids
Short-chain fatty acids (SCFAs) are fatty acids with one to six carbon atoms produced by colonic bacteria when they ferment fibre and other non-digestible carbohydrates. The main ones are acetate, propionate and butyrate.
Educational content for healthcare professionals and the general public. It does not replace assessment by a healthcare professional: ordering and interpreting any test is the responsibility of the requesting clinician.
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