Guide · Lab tests

Chronic inflammation: what it is, how to measure it and what reduces it

The silent inflammation that comes with ageing, the tests that reveal it and the habits with the most evidence for reducing it.

In this article

1. Acute inflammation and chronic inflammation
2. Why chronic inflammation matters for longevity
3. What fuels chronic inflammation
4. Signs and tests for chronic inflammation
5. Habits that reduce chronic inflammation
6. When to see a doctor
7. How to track your inflammation
8. Frequently asked questions
9. Sources

Acute inflammation and chronic inflammation

Inflammation is one of the body's oldest defence tools. When you cut yourself or catch an infection, the immune system recruits cells, increases blood flow and releases chemical signals. The area becomes red, warm and swollen. Once the problem is solved, everything goes back to normal. This is acute inflammation, and it is essential.

Chronic inflammation is a different story. It is a mild, systemic and persistent activation that has no clear target and does not switch off. A perspective published in Nature Medicine calls this state chronic systemic inflammation and describes how social, environmental and lifestyle factors can keep it on for years.

The problem is that it does not hurt. Nobody feels their CRP rising. That is why it often appears only in tests, or once it is already part of a disease.

Why chronic inflammation matters for longevity

The same Nature Medicine perspective links chronic systemic inflammation to several of the leading causes of disability worldwide: cardiovascular disease, cancer, diabetes, chronic kidney disease, fatty liver disease and autoimmune and neurodegenerative diseases.

With ageing, this state tends to settle in. Italian researchers use the term inflammaging to describe the chronic, sterile, low-grade inflammation that develops with age. In a review in Nature Reviews Endocrinology, they propose that chronic diseases, besides resulting from this process, also accelerate ageing. Among the new markers suggested for measuring the gap between biological and chronological age are DNA methylation and metabolomics.

The proof that inflammation and the heart are connected

For decades, the link between inflammation and heart attack was a hypothesis. The CANTOS trial, published in the New England Journal of Medicine, tested an antibody that blocks an inflammatory molecule, interleukin-1β, in 10,061 people who had already had a heart attack and had high-sensitivity CRP of 2 mg/L or more. Without changing cholesterol, the 150 mg dose reduced major cardiovascular events by about 15%.

The study did not change routine prevention, but it confirmed a principle: reducing inflammation, on its own, protects the arteries. For prevention, the good news is that several habits lower these same markers.

What fuels chronic inflammation

The Nature Medicine perspective lists the main factors that promote chronic systemic inflammation:

• Physical inactivity. Spending most of the day sitting is among the most common factors and the easiest to change.
• Poor-quality diet. Too many ultra-processed foods, sugar and low-quality fats.
• Excess visceral fat. The Brazilian dyslipidaemia guideline describes how obesity increases inflammatory cytokines such as TNF-α and IL-6.
• Persistent psychological stress.
• Poor sleep.
• Chronic infections.
• Environmental and industrial toxins, including smoking and air pollution.

The review on inflammaging adds the role of the gut: the microbiota can release inflammatory products and interacts with the circadian rhythm and other organs. Nutrient excess generates a specific form of inflammation, called metaflammation, which follows the same mechanisms as inflammatory ageing.

Signs and tests for chronic inflammation

There is no typical symptom. Some people report tiredness, unrefreshing sleep or diffuse aches, but these signs are non-specific. Chronic inflammation really shows up in tests:

Why does the guideline give CRP this weight? According to the 2025 text, adding high-sensitivity CRP to traditional factors improved risk classification, and a review of four large cohorts showed a gain mainly in people at intermediate risk. That grey zone is where the test helps the doctor most.

CRP rises a lot in acute infections, after intense workouts and with injuries. So, to assess chronic inflammation, the test should be done well away from colds, viral infections or exhausting training, and a single high value should be repeated.

Habits that reduce chronic inflammation

Regular exercise

A meta-analysis published in the British Journal of Sports Medicine pooled 83 controlled studies with 3,769 participants. Physical training reduced CRP regardless of age and sex. The drop was larger when it came with weight or fat loss, but it appeared even without weight loss. In other words, movement counts on its own.

A Mediterranean-style diet

A meta-analysis of 17 randomised trials, with 2,300 participants followed for at least 12 weeks, showed that a Mediterranean-style diet reduced high-sensitivity CRP by almost 1 mg/L and also lowered IL-6, as well as improving blood vessel function. In practice: vegetables, fruit, legumes, whole grains, olive oil, nuts and fish as the base, with little ultra-processed food.

Regular sleep

A meta-analysis in Biological Psychiatry, with 72 studies and more than 50,000 people, associated sleep disturbances with higher CRP and IL-6. Habitually sleeping too long was also associated with more inflammation. Regularity matters as much as quantity.

Where to start

You do not need to change everything at once. A practical sequence that combines the evidence above:

1. Choose a fixed time to go to bed and wake up and protect it for a few weeks.
2. Add movement to the day: walks, stairs, active breaks every hour of sitting, then structured workouts.
3. Build your plate around plants, legumes, olive oil and fish, and cut ultra-processed foods one item at a time.
4. Repeat high-sensitivity CRP after a few months, away from infections, to see the direction.

Small changes that last usually yield more than big changes that are abandoned.

Other fronts

• not smoking and avoiding exposure to smoke;
• reducing belly fat with movement and diet;
• managing stress with breaks, slow breathing, social contact and time outdoors;
• treating chronic infections with the appropriate professional.

When to see a doctor

High-sensitivity CRP persistently above 2 mg/L, in two tests taken away from infections, deserves a conversation with your doctor, especially alongside high cholesterol, raised blood pressure or abnormal blood glucose. Very high values usually point to an acute process, such as an infection, and call for investigating the cause. Fever, unexplained weight loss, persistent joint pain or intense tiredness are also reasons to book an appointment. The doctor decides which further tests make sense and whether any treatment is indicated.

How to track your inflammation

Inflammation is a matter of trends: what matters is the direction of CRP and the other markers over months, alongside sleep, training and stress. Keep your results together and compare them over time.

Frequently asked questions

Sources

1. Furman D et al. Chronic inflammation in the etiology of disease across the life span. Nature Medicine, 2019. doi.org/10.1038/s41591-019-0675-0 · Evidence B
2. Franceschi C et al. Inflammaging: a new immune-metabolic viewpoint for age-related diseases. Nature Reviews Endocrinology, 2018. doi.org/10.1038/s41574-018-0059-4 · Evidence B
3. Ridker PM et al. Antiinflammatory therapy with canakinumab for atherosclerotic disease. New England Journal of Medicine, 2017. doi.org/10.1056/NEJMoa1707914 · Evidence A
4. Fedewa MV, Hathaway ED, Ward-Ritacco CL. Effect of exercise training on C reactive protein: a systematic review and meta-analysis of randomised and non-randomised controlled trials. British Journal of Sports Medicine, 2017. doi.org/10.1136/bjsports-2016-095999 · Evidence A
5. Schwingshackl L, Hoffmann G. Mediterranean dietary pattern, inflammation and endothelial function: a systematic review and meta-analysis of intervention trials. Nutrition, Metabolism and Cardiovascular Diseases, 2014. doi.org/10.1016/j.numecd.2014.03.003 · Evidence A
6. Irwin MR, Olmstead R, Carroll JE. Sleep disturbance, sleep duration, and inflammation: a systematic review and meta-analysis of cohort studies and experimental sleep deprivation. Biological Psychiatry, 2016. doi.org/10.1016/j.biopsych.2015.05.014 · Evidence A
7. Rached FH et al. Diretriz Brasileira de Dislipidemias e Prevenção da Aterosclerose – 2025. Arquivos Brasileiros de Cardiologia, 2025. doi.org/10.36660/abc.20250640 · Evidence A