Cocoa flavanols lowered inflammation markers in aging adults. The effect may help protect cardiovascular health.
Could cocoa extract supplements, which are rich in cocoa flavanols, help reduce inflammation and lower the risk of age-related chronic disease? In a recent investigation from the COcoa Supplement and Multivitamin Outcomes Study (COSMOS), researchers from Mass General Brigham and their collaborators tracked five markers of inflammation linked to aging in participants who took daily cocoa extract supplements for several years.
They observed that levels of hsCRP—an inflammatory protein associated with higher cardiovascular risk—declined in those receiving the supplement. This finding points to an anti-inflammatory effect that may help account for cocoa’s protective influence on heart health. The results were published in Age and Ageing.
Nutritional strategies are gaining attention as promising ways to slow age-related inflammation, often referred to as “inflammaging.” Earlier, smaller studies suggested that cocoa extract could lower inflammatory biomarkers, an effect attributed to flavanols—bioactive compounds present in cocoa beans as well as in foods like berries, grapes, tea, and other plant-based sources. To build on this evidence and better understand its relevance in humans, scientists launched the large-scale COSMOS trial, designed to investigate whether cocoa extract can influence cardiovascular outcomes and whether its benefits may be tied to a reduction in inflammaging.
Trial design and key findings
“Our interest in cocoa extract and inflammaging started on the basis of cocoa-related reductions in cardiovascular disease,” said corresponding author Howard Sesso, ScD, MPH, associate director of the Division of Preventive Medicine and associate epidemiologist at Brigham and Women’s Hospital, a founding member of the Mass General Brigham healthcare system. “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.”
From 2014 to 2020, Brigham and Women’s Hospital conducted the COSMOS trial, a large, randomized, double-blind, placebo-controlled study involving 21,442 participants aged 60 and older. The trial showed that cocoa extract supplementation was linked to a 27% reduction in deaths from cardiovascular disease.
Biomarker results and future directions
In this follow-up analysis, researchers examined blood samples from 598 COSMOS participants to assess markers of age-related inflammation. They focused on three pro-inflammatory proteins (hsCRP, IL-6, and TNF-α), one anti-inflammatory protein (IL-10), and one immune-related protein (IFN-γ). Over the course of baseline, one year, and two years of follow-up, hsCRP levels fell by 8.4% annually in participants taking cocoa extract compared with placebo, while the other biomarkers showed little change or modest increases.
“Interestingly, we also observed an increase in interferon-γ, an immune-related cytokine, which opens new questions for future research,” said senior author Yanbin Dong, MD/PhD, Director of the Georgia Prevention Institute (GPI) and cardiologist/population geneticist at the Medical College of Georgia/Augusta University. “While cocoa extract is not a replacement for a healthy lifestyle, these results are encouraging and highlight its potential role in modulating inflammation as we age.
The decrease in hsCRP may help explain the cardio-protective effects seen with cocoa extract supplement in the larger COSMOS trial, where participants experienced a reduction in cardiovascular disease death. Researchers said that changes in the other inflammaging markers, including a small reduction in IL-6 observed in female but not male participants, warrant additional study. The team will continue to evaluate the COSMOS trial to determine whether the cocoa—and multivitamin—regimens can curb more severe inflammaging, as well as other important aging-related health outcomes.
“This study calls for more attention to the advantage of plant-based foods for cardiovascular health, including cocoa products rich in flavanols,” added Sesso. “It reinforces the importance of a diverse, colorful, plant-based diet—especially in the context of inflammation.”
Reference: “Effects of 2-year cocoa extract supplementation on inflammaging biomarkers in older US adults: findings from the COcoa Supplement and Multivitamin Outcomes Study randomised clinical trial” by Sidong Li, Rikuta Hamaya, Haidong Zhu, Allison Clar, Pamela M Rist, Ying Huang, JoAnn E Manson, Howard D Sesso and Yanbin Dong, 17 September 2025, Age and Ageing.
DOI: 10.1093/ageing/afaf269
Manson and Sesso received investigator-initiated grants from Mars Edge, a segment of Mars Incorporated dedicated to nutrition research and products, for infrastructure support and donation of COSMOS study pills and packaging, and Pfizer Consumer Healthcare (now Haleon) for donation of COSMOS study pills and packaging during the conduct of the study. Sesso additionally reported receiving investigator-initiated grants from Pure Encapsulations, American Pistachio Growers, and Haleon, and honoraria and/or travel for lectures from the Council for Responsible Nutrition, BASF, Haleon, and NIH during the conduct of the study. No other authors reported any conflicts of interests for this study
This work is supported by the National Institutes of Health (HL157665). The COcoa Supplement and Multivitamin Outcomes Study (COSMOS) is supported by an investigator-initiated grant from Mars Edge, a segment of Mars dedicated to nutrition research and products, which included infrastructure support and the donation of study pills and packaging. Pfizer Consumer Healthcare (now Haleon) provided support through the partial provision of study pills and packaging. COSMOS is also supported in part by the National Institutes of Health (AG050657, AG071611, and EY025623). Neither company had a role in the trial design or conduct, data collection, data analysis, or manuscript preparation or review.
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