Not Quite Right: 500mg of Flavanols a Day Isn't a Magic Number for Heart Health

You may have seen the claim circulating online: get 500 milligrams of flavanols a day and you'll protect your heart. It sounds precise and actionable. The problem is the science doesn't support a single magic number — and 500mg is not a firmly established threshold for cardiovascular benefit.

The 500mg figure likely comes from the COSMOS-Cocoa trial, a large study of over 21,000 participants published in the New England Journal of Medicine in 2022. Researchers tested a 500mg daily cocoa flavanol supplement and found a reduction in cardiovascular mortality in a subgroup analysis. But the trial did not find a significant reduction in major cardiovascular events overall. That's a meaningful distinction — and it means 500mg is a dose that was tested, not a proven optimal minimum.

Meanwhile, the European Food Safety Authority authorized a health claim for cocoa flavanols at just 200mg per day, specifically for maintaining healthy blood vessel function. A 2020 review in the journal Nutrients found that cardiovascular benefits — including lower blood pressure and improved endothelial function — appear across a broad range of 200 to 1000mg per day. No single cut-off has been universally established.

To be fair, 500mg isn't a bad number. A 2022 paper in Frontiers in Nutrition proposed a dietary reference value of 400 to 600mg per day for cardiovascular health, putting 500mg squarely in a plausible range. But "plausible range" and "the level associated with benefits" are very different claims. The honest answer is that the research points to a spectrum, not a single target.

This kind of misinformation is easy to miss because it's not entirely wrong — it just strips away the nuance. Watch out for precise-sounding numbers in nutrition headlines. A specific figure feels more credible and useful than "somewhere between 200 and 1000mg," even when the latter is closer to the truth.