High-Sensitivity C-Reactive Protein (hs-CRP)

High-sensitivity C-reactive protein (hs-CRP) is a protein produced by the liver in response to inflammation. Inflammation is the body’s natural defence process against infection, injury, or stress. While short-term inflammation is protective, long-term or low-grade inflammation can quietly contribute to chronic diseases — particularly those affecting the heart and blood vessels. hs-CRP is a more precise version of the traditional CRP test and can detect very small increases in inflammation that would otherwise go unnoticed.

Because hs-CRP responds to even subtle inflammatory activity, it is used to help identify people who may have hidden inflammation that elevates their risk for conditions such as coronary artery disease. Even when cholesterol, blood pressure, and glucose appear normal, hs-CRP can show whether inflammation is amplifying risk. This makes the test valuable in preventative health, especially for people with borderline or unclear cardiovascular risk profiles.

Importantly, hs-CRP does not tell where inflammation is coming from. Levels can rise from infections, chronic conditions, autoimmune disorders, or lifestyle factors such as poor diet, smoking, or inactivity. Its power lies in showing the overall inflammatory burden, allowing clinicians to understand whether inflammation is contributing to disease risk or worsening existing conditions.

Inflammation plays a major role in nearly every stage of cardiovascular disease, from the early buildup of plaque in arteries to the rupture of that plaque, which can trigger a heart attack or stroke. High hs-CRP levels indicate more active inflammation, and decades of clinical research show that people with elevated hs-CRP are significantly more likely to develop cardiovascular events, even when their cholesterol levels appear healthy. This is why leading cardiology organisations consider hs-CRP one of the most useful tools for refining cardiovascular risk.

When inflammation is chronic, the walls of blood vessels become more vulnerable. They attract immune cells, accumulate cholesterol more rapidly, and lose their ability to relax and maintain proper blood flow. This sets the stage for atherosclerosis (artery narrowing) and plaque instability. High hs-CRP reflects this internal activity and can serve as an early warning sign long before symptoms appear. People with persistent hs-CRP elevation may benefit from lifestyle changes or medical interventions aimed at lowering inflammation and improving heart health.

hs-CRP is also valuable beyond heart disease. It rises with infections, injuries, metabolic dysfunction, and autoimmune conditions. By signalling that the body is under stress, hs-CRP helps clinicians understand when inflammation may be contributing to fatigue, pain, or metabolic changes. When levels are above 10 mg/L, the elevation is often due to an acute illness such as a cold, flu, or significant infection, and retesting after recovery provides a clearer picture.

The test is particularly useful when other markers — such as cholesterol, blood pressure, or glucose — do not fully explain someone’s health picture. For example, two people with similar cholesterol levels may have very different cardiovascular risks if one has high hs-CRP and the other does not. Research also shows that reducing inflammation through lifestyle improvements or appropriate medications lowers hs-CRP and reduces the likelihood of cardiovascular events.

• Optimal: <1 mg/L

• Suboptimal: 1-3mg/L

• Elevated: >3mg/L

Dietary factors

Eating patterns have a strong influence on inflammation. Diets high in processed foods, refined sugars, and unhealthy fats tend to increase inflammatory activity and elevate hs-CRP. In contrast, anti-inflammatory diets — emphasising colourful fruits and vegetables, whole grains, legumes, nuts, olive oil, and fatty fish (2–3 servings weekly) — are associated with lower hs-CRP levels.

Lifestyle habits

Smoking, excess alcohol intake, chronic stress, and physical inactivity all raise inflammation and can increase hs-CRP. Regular movement, prioritising sleep, stress management, and maintaining a healthy body weight contribute to lower inflammatory levels.

Medical and biological factors

Acute infections, chronic inflammatory diseases (such as arthritis), diabetes, obesity, and autoimmune conditions can raise hs-CRP. Levels above 10 mg/L are often caused by infection or acute illness and should be rechecked when you are well.

Micronutrient and metabolic influences

Insulin resistance, metabolic dysfunction, and inflammatory adipose tissue raise hs-CRP. Certain medications — such as statins and bempedoic acid — can help lower inflammation and hs-CRP when medically appropriate.

Related biomarkers

hs-CRP is typically interpreted alongside cholesterol levels, blood pressure, glucose markers, and sometimes ferritin or other inflammatory markers to build a full picture of cardiovascular and metabolic risk.

If hs-CRP is high:

• Build a Mediterranean-style pattern. Meals rich in extra-virgin olive oil, vegetables, legumes, whole grains, nuts, and herbs have the best evidence for lowering CRP among dietary patterns. An umbrella review found the Mediterranean diet most effective for reducing circulating CRP compared with other patterns.

• Train consistently. Exercise reduces CRP, and the effect is stronger when body fat comes down. A meta-analysis of 83 trials found a small but significant reduction in CRP with training, with larger drops when BMI or body fat decreased. Combine aerobic and resistance work you can keep up most weeks.

• Layer anti-inflammatory habits.

  • Choose minimally processed foods and cook with olive oils

  • Get regular, sufficient sleep and a consistent sleep–wake schedule.

  • Avoid smoking and second-hand smoke.

  • Keep weight trending toward your personal healthy range, since fat loss amplifies hs-CRP improvements from diet and exercise.

1. Markers of Inflammation and Cardiovascular Disease, Application to Clinical and Public Health Practice – CDC and American Heart Association (AHA), 2003. https://www.ahajournals.org/doi/pdf/10.1161/01.cir.0000052939.59093.45
   

2. 2019 ACC/AHA Guideline on the Primary Prevention of Cardiovascular Disease – American College of Cardiology/American Heart Association, 2019. https://www.ahajournals.org/doi/pdf/10.1161/CIR.0000000000000678
   

3. Evaluating the effects of dietary patterns on circulating C-reactive protein levels, umbrella review of meta-analyses – Cambridge University Press (British Journal of Nutrition), 2024. https://www.cambridge.org/core/services/aop-cambridge-core/content/view/A22B85D3CECD3027134A0489121E8B70/S0007114524001648a.pdf
   

4. Effect of exercise training on C-reactive protein, systematic review and meta-analysis – British Journal of Sports Medicine, 2016. https://www.researchgate.net/profile/Michael-Fedewa-2/publication/305518565_Effect_of_exercise_training_on_C_reactive_protein_A_systematic_review_and_meta-analysis_of_randomised_and_non-randomised_controlled_trials/links/5c7d3f2da6fdcc4715ae1834/Effect-of-exercise-training-on-C-reactive-protein-A-systematic-review-and-meta-analysis-of-randomised-and-non-randomised-controlled-trials.pdf
   

5. Treatment of periodontitis and C-reactive protein, systematic review and meta-analysis of randomised clinical trials – Journal of Clinical Periodontology (UCL open-access), 2023. https://discovery.ucl.ac.uk/id/eprint/10153943/