A large clinical trial found cocoa extract cut levels of hsCRP, an inflammation marker, by about 8.4% per year.
Other markers showed mixed results, with a small IL-6 reduction in women but no broad changes.
Findings may explain part of cocoa’s heart health benefits seen in earlier COSMOS results.
A new analysis from the COSMOS trial suggests that cocoa extract could help reduce age-related inflammation.
Researchers reported that adults who took a flavanol-rich cocoa supplement daily for two years had significantly lower levels of hsCRP, a well-known marker of systemic inflammation and cardiovascular risk.
“Our interest in cocoa extract and inflammaging started on the basis of cocoa-related reductions in cardiovascular disease,” researcher Howard Sesso, ScD, MPH, said in a news release.
“We also appreciate the important overlap between healthy aging and cardiovascular health, where aging-related inflammation can harden arteries and lead to cardiovascular disease. Because of that, we wanted to see whether multi-year cocoa extract supplementation versus a placebo could modulate inflammaging — and the data suggests it does.”
The study
The findings come from a substudy within COSMOS, a nationwide clinical trial involving over 21,000 older adults. For this analysis, scientists focused on 598 participants who provided blood samples at the start, after one year, and after two years. Participants were randomly assigned to take either cocoa extract capsules or placebo, without knowing which they received.
Blood tests measured five key proteins:
hsCRP (C-reactive protein): a marker linked to cardiovascular risk
IL-6 and TNF-α: pro-inflammatory proteins
IL-10: an anti-inflammatory protein
IFN-γ: an immune signaling protein
This design allowed researchers to track whether cocoa supplementation influenced inflammation compared to placebo over time.
The results
The standout result was a steady reduction in hsCRP: about 8.4% lower each year in the cocoa group versus placebo. Researchers say this may help explain the cardiovascular benefits tied to cocoa extract in earlier COSMOS reports.
Other results were less consistent:
IL-6 dropped modestly in women but not men.
TNF-α and IL-10 showed little change.
IFN-γ levels actually increased, a surprising finding the team says needs more study.
Overall, the data suggest cocoa extract could play a role in easing age-related inflammation, though its effects appear strongest for hsCRP. Researchers caution that supplements are not a substitute for healthy lifestyle habits, but the results add another piece to the puzzle of how cocoa may support heart health and aging.
“This study calls for more attention to the advantage of plant-based foods for cardiovascular health, including cocoa products rich in flavanols,” Sesso said. “It reinforces the importance of a diverse, colorful, plant-based diet — especially in the context of inflammation.”