“Reduces inflammation” is the most-used phrase in nutrition writing and the least often defined. Inflammation in what tissue, measured how, compared with what? This article answers those questions, because once you know what is actually being measured, most of the claims in this field become easy to sort.
The short version
- Acute and chronic inflammation are different things. Acute lasts days; chronic runs for months to years.
- CRP is the usual measurement — and it is non-specific. It tells you how much inflammation you have, “but not what’s causing it or where it is.”
- No agency recommends hs-CRP testing for healthy people. The US Preventive Services Task Force rates the evidence insufficient.
- The only proof that lowering inflammation lowers heart attacks came from a drug — and that drug also increased fatal infections.
- The Dietary Inflammatory Index scores diets, not people. It is a literature-derived algorithm frozen at December 2010.
- Watch the units: 1.0 mg/dL and 1.0 mg/L are not the same number.
Two different things share one word
Acute inflammation is the response to injury or infection. It “starts rapidly, becomes severe in a short time and symptoms may last for a few days.” It is not a malfunction — it is how tissue repair begins.
Chronic inflammation is a different phenomenon that borrowed the name: “slow, long-term inflammation lasting for prolonged periods of several months to years.” Between them sits subacute inflammation, roughly two to six weeks.
What nutrition articles usually mean is a third thing again, generally called systemic chronic inflammation in the literature. A 2019 paper in Nature Medicine describes it as a state that certain social, environmental and lifestyle factors can promote, and which is associated with cardiovascular disease, cancer, diabetes, kidney and liver disease and more. Associated. That word is doing a great deal of work, and the rest of this article is about how much.
CRP: what the test measures and what it cannot
C-reactive protein is made by the liver in response to inflammation, and a blood test measures it. Its central limitation is worth memorising, in the words of the National Library of Medicine: “Your CRP test results tell you how much inflammation you have in your body, but not what’s causing it or where it is.”
A high-sensitivity version, hs-CRP, detects much smaller increases and is used to estimate cardiovascular risk. The familiar three-band scale comes from a 2003 CDC and American Heart Association scientific statement:
| hs-CRP | Category |
|---|---|
| Below 1.0 mg/L | Low relative cardiovascular risk |
| 1.0 to 3.0 mg/L | Average |
| Above 3.0 mg/L | High |
| Above 10 mg/L | Repeat the test and look for infection or another inflammatory source |
A units trap that ruins home comparisons. MedlinePlus reports ordinary CRP in mg/dL and gives a normal range of about 0.8–1.0 mg/dL or lower. The cardiology hs-CRP cut-offs above are in mg/L. The two scales differ by a factor of ten. If you are reading your own lab report against a number from an article, check which unit each is using before drawing any conclusion.
The same 2003 statement also specifies how the measurement should be done: twice, averaged, ideally two weeks apart, in a metabolically stable person. A single reading is not a result.
Should you get tested? Every agency says no
This is unusually clear for a nutrition topic. The 2003 CDC and AHA statement says outright: “The entire adult population should not be screened for hs-CRP for purposes of cardiovascular risk assessment.”
The US Preventive Services Task Force reached the same place in 2018, giving a Grade I — insufficient evidence — for adding hs-CRP to traditional cardiovascular risk assessment in asymptomatic adults. Where hs-CRP does appear in current practice is narrow: the 2019 ACC/AHA primary prevention guideline lists an elevated value of 2.0 mg/L or above as one “risk-enhancing factor” among many, used to help decide a treatment question in someone already being assessed.
So a CRP result cannot tell you whether your diet is working. It is not specific to diet, not specific to a site in the body, and moves with any infection you happen to be fighting that week.
The one experiment that proved the concept — and it was a drug
If chronic inflammation causes cardiovascular events, then reducing it should reduce events. That has been tested. The CANTOS trial gave 10,061 people who had already had a heart attack and had elevated hs-CRP an injected anti-inflammatory antibody, canakinumab, every three months.
At the 150 mg dose, the rate of cardiovascular death, heart attack or stroke fell from 4.50 to 3.86 events per 100 person-years (p=0.02). The 50 mg and 300 mg doses did not reach significance. And there was a cost: fatal infection or sepsis rose from 0.18 to 0.31 per 100 person-years, also p=0.02.
What CANTOS does and does not license you to say. It supports the underlying idea that inflammation is part of the causal chain in cardiovascular disease. It does not support any claim about food, because the intervention was a targeted monoclonal antibody at a specific dose in people who had already had a heart attack. As the NHLBI’s own scientist put it, “The immune system is complex. Manipulating one part of it could have unknown and/or unintended consequences.”
The Dietary Inflammatory Index, explained properly
The DII is the tool behind most headlines of the form “a pro-inflammatory diet was linked to X.” Knowing what it is changes how you read them.
It was built by screening around 6,500 publications and scoring roughly 1,943 of them, through December 2010, to assign inflammatory scores to 45 food parameters against six biomarkers: IL-1β, IL-4, IL-6, IL-10, TNF-α and CRP. Its stated purpose was “to compare diverse populations on the inflammatory potential of their diets.”
Three consequences follow. It scores a diet using published literature — it does not measure inflammation in the person eating it. Its evidence base stops in 2010. And it is a research instrument, not a clinical or diagnostic test: no agency endorses it for individual use. A study reporting that a “high DII” diet was associated with an outcome has scored questionnaires, not measured anyone’s blood.
Why studies in this field keep disagreeing
Three structural reasons, all visible in the primary literature.
- The comparator is never the same. The umbrella review of anti-inflammatory dietary patterns flags “significant heterogeneity of comparator diets” — a Mediterranean diet tested against a low-fat diet and against a typical Western diet are two different experiments.
- Marker panels differ. A 2025 meta-analysis of 18 trials could pool hs-CRP from only five of them, and could not pool IL-6 or TNF-α at all.
- Most of the evidence is observational and short. The VA review notes that researchers must rely on “prospective cohort studies of relatively short-term duration,” and that on inflammation’s causal role, “direct evidence is generally lacking.”
What this means in practice
You cannot measure your own inflammation usefully, you cannot verify that a food changed it, and the diets that show the best signal in pooled research are the same ones already recommended for blood pressure and cholesterol — where the evidence is far stronger. That is not a disappointing conclusion. It means the correct action is the ordinary one, and you can stop paying a premium for the word “anti-inflammatory” on a package.
FAQ
What is a normal CRP level?
MedlinePlus gives roughly 0.8–1.0 mg/dL or lower for standard CRP. For hs-CRP, the cardiovascular bands are below 1.0 mg/L, 1.0–3.0 and above 3.0 mg/L. Different units — do not compare them directly, and interpret any result with the clinician who ordered it.
Can I lower my CRP with diet?
Pooled trials of anti-inflammatory dietary patterns found a hs-CRP effect that was borderline and drawn from few studies, while blood pressure and cholesterol improved clearly. Treat CRP as a research endpoint, not a personal target.
Is chronic low-grade inflammation a diagnosis?
No. There is no accepted clinical definition or diagnostic threshold. The term in the research literature is systemic chronic inflammation, and it is a description of an associated state, not a condition you can be diagnosed with at a checkup.
Why do so many articles say the opposite of each other?
Different comparator diets, different marker panels, mostly observational designs, and a scoring index whose literature base ends in 2010. Those four things account for most of the contradiction.
Does that mean diet does not matter here?
It matters — the effects on blood pressure and cholesterol are real and well measured. What is weak is specifically the inflammation framing used to sell it.
Where this fits
For what to actually eat, see anti-inflammatory foods: what the evidence actually supports. For the popular list of individual foods checked one by one against NIH and NCCIH, see inflammatory vs anti-inflammatory foods.
Every figure here is linked to its source in the text: MedlinePlus and the National Library of Medicine, the CDC/AHA scientific statement in Circulation, the US Preventive Services Task Force, the 2019 ACC/AHA primary prevention guideline, the NHLBI, the US Department of Veterans Affairs Evidence Synthesis Program, and peer-reviewed papers in Nature Medicine and Public Health Nutrition. Checked against those sources on 1 September 2026. Educational information, not medical advice — see our medical disclaimer.
This content is for educational purposes only and is not medical advice. Always consult a qualified healthcare professional for personalised guidance.
