Protocol · not graded
Cocoa flavanol supplementation (polyphenols)
A cocoa extract providing 500 mg of flavanols a day, tested for cardiovascular events in older adults.
At a glance
This page is about a cocoa extract pill, rich in plant compounds called flavanols. One very large trial gave it or a dummy pill to over 21,000 older adults for about three and a half years. It did not clearly lower heart attacks and strokes, the main question. Fewer people died of heart disease, but that was a side question and needs repeating.
Cardiovascular events in older adults: primary endpoint The one outcome a trial names in advance as its main test. Results on other outcomes carry less weight. missed in one large trial; not graded.
Why this letter
Not graded. One large randomized trial missed its primary cardiovascular endpoint The outcome a trial measures to decide whether the treatment worked, such as heart attacks, blood pressure or a symptom score.; the lower cardiovascular death rate was a secondary outcome and has not been replicated The same finding reproduced by a separate research group. A result seen once can be chance or bias; a replicated one is harder to explain away..
Evidence notes: randomized trial, not independently replicated
Last reviewed: October 2026
Dose, form and timing
No outcome target is established.
Grade history
How this letter has changedLatest: No. 352 · October 2026 · Corrected.
The nutrition page's polyphenol entry had no citation. It now cites COSMOS (Sesso et al., Am J Clin Nutr, 2022; PMID PubMed ID: the permanent number the US National Library of Medicine gives a published paper. Each one links to that paper's record on PubMed. 35294962): 21,442 older adults, 500 mg of cocoa flavanols a day for a median 3.6 years, with total cardiovascular events not significantly lower and cardiovascular deaths lower as a secondary outcome. One trial that missed its primary endpoint carries no letter.PMID 35294962
Every change to a letter on this site is dated and published. The full evidence log →
Sources
The evidence, in fullOne paper, linked to its PubMed record.
Sesso et al. (Am J Clin Nutr, 2022; PMID 35294962), COSMOS: 21,442 older US adults randomized to a cocoa extract supplement providing 500 mg of flavanols a day or placebo An inactive substitute made to look like the real treatment, so participants cannot tell which one they received., median 3.6 years. Total cardiovascular events were not significantly reduced (hazard ratio How often an event happened in the treated group compared with the control group over the same period. A ratio of 0.80 means 20 percent fewer events. 0.90, 95% CI 0.78 to 1.02). Cardiovascular death, a secondary outcome, was lower (hazard ratio 0.73, 95% CI 0.54 to 0.98).
Disclosure
Educational use only · Not medical advice · EBL grades published human evidence and does not recommend treatment.
Evidence Based Longevity, Inc. is owner-operated and edited by Arnold Sandlow, D.C., a California-licensed chiropractor. Evidence Based Longevity publishes in English only · Machine translations are not produced or reviewed by EBL for accuracy
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