Cocoa flavanols for 3.6 years: primary vs secondary results explained
COSMOS gave thousands of older adults a cocoa flavanol capsule for years. The result that the trial was built to answer, and a later result that it was not built to answer, do not say the same thing. Neither result is a chocolate bar.
Short answer
- About 21,000 older adults, 500 mg cocoa flavanols a day, in a capsule, for a median of 3.6 years.
- Primary outcome: total cardiovascular events were not significantly lower.
- Secondary: cardiovascular deaths were about 27% lower. A secondary result only suggests a next study.
- A companion cognition paper found no benefit of the cocoa extract on its global cognition score.
The trial: a capsule, not chocolate
Sesso and colleagues reported the cardiovascular paper in the American Journal of Clinical Nutrition (2022). Participants took cocoa extract with 500 mg of flavanols a day, or a placebo. The dose was a capsule from the trial pharmacy. It was not a square of chocolate, and the trial does not grade any brand of bar.
Primary first
The primary outcome was total cardiovascular events (a composite the protocol named in advance). Those events were not significantly lower with the cocoa extract. If you only remember one line, remember that one. A trial is allowed one main question. COSMOS did not clear it.
Why the 27% line is secondary
Cardiovascular deaths were lower, by about 27%, in a secondary analysis. Secondary means the trial was not sized and locked to answer that question alone. A real difference can show up there. It can also be chance, or one slice of a bigger picture that did not move. The honest use of a secondary result is a hypothesis for a new study, not a claim that the capsule prevents death.
Cognition, as the paper reported it
Baker and colleagues tested cognition in COSMOS-Mind (Alzheimer's & Dementia, 2023). Daily cocoa extract for three years had no effect on the global cognition score (mean z 0.03, confidence interval crossing zero). That is the cocoa result. It is not a reason to start any other supplement that happened to be in the same factorial design.
A capsule is not a chocolate bar
Halloween or not, the study object was a measured flavanol capsule. A bar of chocolate brings sugar, fat and a much less controlled dose. Liking chocolate is fine. It is not what COSMOS tested.
This post is general information, not medical or dietary advice.
Sources
- Sesso H. D. et al. (2022), cocoa flavanols and cardiovascular outcomes in COSMOS, American Journal of Clinical Nutrition. PubMed
- Baker L. D. et al. (2023), cocoa extract, a multivitamin and cognition in COSMOS-Mind, Alzheimer's & Dementia. PubMed
Video transcript
Twenty-one thousand older adults took cocoa flavanols for three and a half years. Result?
They took five hundred milligrams of cocoa flavanols a day in a capsule. Not chocolate.
Total heart and blood vessel events weren't significantly lower. That was the main outcome. Heart deaths were twenty-seven percent lower, but that was a secondary result.
Secondary results only give ideas for new studies. And again: this was a capsule, not a chocolate bar.
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This blog does not give medical advice. Health disclaimer.