A little, and not reliably. A 2026 meta-analysis pooled 24 randomized trials with 2,068 adults. Daily walnuts came with small drops in CRP and IL-6, two blood markers of inflammation, and no change in three others. The drops looked bigger past 12 weeks and above 50 grams a day, but they faded when a few influential trials were removed.
What the new study did
A research team searched the medical databases through July 2026 for every randomized controlled trial that fed adults walnuts and then measured inflammation. In a randomized trial, chance decides who gets the walnuts, so the two groups start out alike. A meta-analysis pools those trials into one bigger answer.
They found 24 trials with 2,068 people between them. That is a decent haul for a single food. It also works out to about 86 people per trial, which matters later.
Five things were measured. Three are inflammation signals: C-reactive protein (CRP), a protein the liver releases when the body is inflamed, plus interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-alpha), two messenger proteins the immune system uses. The other two are adipokines, hormones made by fat tissue: adiponectin and leptin. The team also checked whether more walnuts meant more change, and whether the answer survived dropping single trials. Both checks turned out to matter.
What it found: do walnuts reduce inflammation?
Two of the five markers moved. Here is the paper's own scorecard, showing the average difference between walnut eaters and the comparison groups at the end of the trials.
Two of five inflammation markers moved with walnuts, and the authors say the change did not hold once a few influential trials were removed.From a 2026 meta-analysis in J Hum Nutr Diet
| Marker | Average difference with walnuts | Range the authors consider plausible | Moved? |
|---|---|---|---|
| CRP | -1.0 mg/dL, as printed | -1.9 to -0.1 | Yes, small |
| IL-6 | -0.11 pg/mL | -0.20 to -0.01 | Yes, small |
| TNF-alpha | +0.21 pg/mL | not significant (p = 0.306) | No |
| Adiponectin | -0.17 ng/mL | not significant (p = 0.678) | No |
| Leptin | +1.39 ng/mL | not significant (p = 0.314) | No |
Look at the CRP range. Both ends sit below zero, which is what makes it count as a real difference. But it is wide: the true effect could be close to the full 1.9, or a tenth of that.
How many walnuts a day?
Two patterns are worth knowing. Trials that ran longer than 12 weeks showed larger anti-inflammatory effects, and so did trials that used more than 50 grams of walnuts a day. Walnut trials overall have used anywhere from about 10 to 99 grams a day, and a 3-week gut study used 42 grams. Fifty grams is a generous handful of halves. Over 12 weeks it adds up: 50 grams times 84 days is 4,200 grams, about 4.2 kilograms of walnuts. That is what the stronger trials asked people to get through.
What it can't tell us
Start with the authors' own caution. When they left out several influential trials, the CRP and IL-6 drops were no longer clear. A result that depends on a few trials is a result that could flip. That is why we grade this Emerging rather than Moderate. With about 86 people in the average trial, a wobble in one or two studies can tilt the pooled number.
There is also a unit puzzle. The abstract prints the CRP result in mg/dL. Most labs and most trials report CRP in mg/L, a unit ten times smaller; the 2017 review of nuts and inflammation used mg/L. Read as mg/dL, a 1.0 drop would be very large, yet the authors describe their effect as small and modest. We could not settle this from the abstract, so trust the direction more than the decimal.
And markers are not outcomes. Nobody in these trials was followed to see whether they had fewer heart attacks or less joint pain. The authors say the clinical relevance of the change remains uncertain.
How it fits with earlier research: are nuts anti-inflammatory?
Earlier reviews pooled all nuts together. A 2017 meta-analysis of 32 randomized trials of tree nuts and peanuts found CRP almost unchanged: an average difference of 0.01 mg/L across 25 studies, with the plausible range straddling zero. Its authors found no consistent evidence that nuts affect inflammation, though nuts did improve how well arteries relax. A 2018 meta-analysis of 23 trials found one marker that fell with nuts: ICAM-1, a sticky molecule on blood vessel walls, especially in trials of 12 weeks or more.
Walnut-only reviews tell a similar story. A 2022 systematic review of 23 walnut trials, at doses from about 10 to 99 grams a day, found no consistent direction of effect for inflammation markers and judged only one trial to be at low risk of bias. In 2026 the team behind the new meta-analysis pooled 36 walnut trials on blood vessels. Walnuts improved flow-mediated dilation, a test of artery relaxation, by 0.93 percentage points, and ICAM-1 fell more at higher intakes and in people at high cardiovascular risk.
So here is the pattern across a decade of pooling. Walnuts change blood fats and artery function clearly, and inflammation markers a little, late, and at larger doses. In 13 trials, walnuts lowered total cholesterol by 8.58 mg/dL, LDL cholesterol by 5.68 and triglycerides by 10.94.
Why would walnuts do anything at all? They are a main food source of alpha-linolenic acid (ALA), a plant omega-3 fat, and some ALA trials point to an anti-inflammatory effect. The 3-week feeding study of 18 adults also shifted gut bacteria toward butyrate producers and cut two bile acids the authors call pro-inflammatory by 25% and 45%. That is a plausible route, not a proven one.
Should you change anything?
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you have a tree nut allergy or have ever reacted to walnuts; you are on a medically supervised eating plan that limits fat or calories; or you hope a food change can stand in for a medicine for cholesterol, blood pressure or an inflammatory condition. Keep taking it as prescribed and ask before changing anything.
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How this article was made
Researched and written from 9 peer-reviewed papers. Our automated check matched every claim against the exact words of its source, confirmed every paper exists in PubMed, and found none retracted. Checked November 3, 2026. Not individually reviewed by a doctor. Photos are illustrative; the people in them are not patients or readers.
Grades run Strong, Moderate, Emerging, Early and Not supported, and the grade decides the words we may use. How we grade evidence · Medical disclaimer
Sources
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