Chronic Conditions and Diseases
Chronic Conditions and Diseases
Cocoa Extract and Blood Pressure
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A 2025 study conducted by the Harvard Osher Center for Integrative Medicine, part of Brigham and Women’s Hospital and Harvard Medical School, explored whether cocoa flavanols (the natural compounds found in cocoa, the plant ingredient used to make chocolate) can help prevent high blood pressure. Earlier small studies had suggested cocoa might have blood pressure–lowering benefits, but no large, long-term trials had confirmed this.
The COcoa Supplement and Multivitamin Outcomes Study (COSMOS) included over 21,000 older adults (women aged 65 and older, men aged 60 and older) who were randomly assigned to take either a daily cocoa extract capsule, a placebo, a multivitamin, or both. The cocoa extract provided 500 milligrams of cocoa flavanols per day.
Among 8,905 participants who did not already have high blood pressure, researchers followed them for more than three years to see who developed hypertension, defined as a doctor’s diagnosis, starting medication, or high readings.
The cocoa extract did not significantly reduce the number of new cases—about 7 out of every 100 people developed high blood pressure each year in both the cocoa and placebo groups.
However, the researchers wanted to examine this further. They divided the “healthy” groups into two subgroups: those who began the study with healthy blood pressure (below 120 mm Hg systolic) and those who began with elevated—but not high—blood pressure (120 to 129 systolic).
With these subgroups analyses, the researchers discovered that for participants who began the study with healthy blood pressure, those taking cocoa extract had a 24% lower risk of developing hypertension compared to those on placebo. This benefit became noticeable after about two years. People who started with elevated blood pressure did not experience the same protective effect.
In short, this large Harvard-led study found that long-term cocoa extract may help maintain healthy blood pressure but does not prevent hypertension if blood pressure is already elevated.
REFERENCES
COSMOS Research Group. Long-Term Effect of Cocoa Extract Supplementation on Incident Hypertension. Hamaya R, Li S, Lau J, Allison M, Haring B, Shadyab AH, Matthew N, Martin LW, Rist PM, Manson JE, Sesso HD; Hypertension. 2025 Aug 20. doi: 10.1161/HYPERTENSIONAHA.125.25209.
