A new large scale clinical study suggests that daily cocoa extract supplements rich in flavanols could slow one of the most damaging biological processes of aging – chronic low-grade inflammation, also known as inflammaging.
The study “Effects of 2-year cocoa extract supplementation on inflammaging biomarkers in older US adults” was conducted by researchers from Mass General Brigham and Augusta University, led by Sidong Li, Howard D. Sesso, JoAnn E. Manson and Yanbin Dong. It was published in September 2025 in Age and Ageing (Oxford University Press) as part of the large-scale COSMOS trial, and funded by the National Institutes of Health (NIH), with supplementary support from Mars Edge and Pfizer Consumer Healthcare (now Haleon).
Daily cocoa extract may slow “inflammaging”
Researchers found that cocoa flavanols significantly reduced levels of high sensitivity C-reactive protein (hsCRP), a key biomarker linked to inflammation and cardiovascular disease.
Over a two-year randomized, double-blind, placebo-controlled trial involving 598 older adults (part of the 21,442 participants in COSMOS), those who took daily cocoa extract supplements experienced an 8.4% yearly reduction in hsCRP compared to placebo.
This decrease may help explain prior COSMOS results showing that cocoa extract supplementation reduced cardiovascular disease mortality by 27% between 2014 and 2020.
Howard D. Sesso, ScD, MPH, of Brigham and Women’s Hospital: “We wanted to see whether multi-year cocoa extract supplementation could modulate inflammaging – and the data suggests it does.”
Why this matters for healthy aging
Inflammaging – the chronic, low-level inflammation that develops with age – plays a central role in cardiovascular disease, diabetes, neurodegeneration and frailty.
The fact that cocoa extract reduced hsCRP – a validated predictor of heart disease risk – suggests flavanol-rich cocoa may act as a nutritional tool to slow inflammatory aging and protect long-term cardiovascular health.
This reinforces a growing body of evidence showing that plant-based diets rich in polyphenols and flavanols can support longevity by improving endothelial function, reducing oxidative stress and modulating immune signaling.
“This study reinforces the importance of a diverse, colorful, plant-based diet — especially in the context of inflammation,” said Sesso.
Study design in brief
| Feature | Description |
| Trial name | COSMOS: COcoa Supplement and Multivitamin Outcomes Study |
| Design | Randomized, double-blind, placebo-controlled, 2×2 factorial |
| Participants | 21,442 adults (≥60 men, ≥65 women); 598 analyzed for inflammaging |
| Duration | 2 years (blood samples at baseline, 1 and 2 years) |
| Intervention | 500 mg/day cocoa flavanols, including 80 mg (−)-epicatechin |
| Main finding | ↓ hsCRP (−8.4%/year) and ↑ IFN-γ (+6.8%/year) |
| Publication | Age and Ageing (Oxford University Press, Sept 2025) |
Practical implications for longevity and daily life
1. Cocoa extract (500 mg/day of flavanols) may help reduce inflammation and support cardiovascular longevity:
- Supplements used in the COSMOS study were standardized for flavanol content, not sugar or caffeine.
2. Flavanols are also abundant in natural cocoa powder, dark chocolate (≥85% cacao), berries, grapes, and green tea.
3. Synergy with other nutrients: anti-inflammatory benefits may be enhanced by combining cocoa flavanols with omega-3 fatty acids, curcumin or vitamin D, all of which modulate immune pathways.
4. Lifestyle context matters: regular exercise, good sleep and a fiber-rich diet amplify the anti-inflammatory effects of flavanols.
Caution: Commercial chocolate bars are often high in sugar and low in bioactive flavanols. They do not replicate these effects.
