Your Five-a-Day Isn't Enough Flavanols, Says the Company That Sells Them by the Capsule

Flavanols charmed me before they made me suspicious. They’re the plant compounds in cocoa, tea, apples, and berries that coax your blood vessels into relaxing, partly by helping the lining of your arteries make more nitric oxide, the signaling molecule that tells a vessel to open up and let blood through. Eat your blackberries, dilate your arteries, live forever. I came to this story ready to be delighted.

Then I read the author list.

The study that landed last week carries a clean, alarming message: do everything the official dietary guidelines tell you, eat your five servings of fruit and veg a day, and you still probably won’t get enough flavanols to protect your heart. The researchers measured flavanol intake in more than 30,000 people across two cohorts, the American COSMOS group and Britain’s EPIC-Norfolk, and found that fewer than one in five hit the target. Precisely 19.2 percent in the US sample, 17.9 percent in the UK. Even among the dutiful people who were clearing their five-a-day, fewer than a quarter reached it. The paper ran June 8 in the Royal Society of Chemistry journal Food & Function.

What’s the target? Five hundred milligrams of flavanols a day. Hold that number. We’re coming back to it.

First, credit where it’s due, because I want to be fair to the science before I’m hard on the salesmanship. This study did something most nutrition research doesn’t. Instead of asking people to remember what they ate last Tuesday, which is how most of these studies generate their gloriously unreliable data, the team used two validated urinary biomarkers, the molecules your body produces when it metabolizes flavanols, to estimate real intake. That’s a better mousetrap. Food diaries drift; people misremember lunch. A biomarker is harder to fool. So when they say most people are low, I believe the measurement.

It’s the conclusion drawn from the measurement that needs a closer look.

The lead author, Javier Ottaviani, is described in the press materials as a researcher affiliated with UC Davis. True, as far as it goes. He’s also the director of the Core Laboratory of Mars Edge, the nutrition arm of Mars, Incorporated. A co-author, Hagen Schroeter, is likewise a Mars employee. The paper’s own disclosure says it plainly: both are “employed by Mars, Incorporated, a company engaged in flavanol research and flavanol-related commercial activities.” The flavanol data came from COSMOS, a trial supported by an investigator-initiated research grant from Mars Edge, which also donated the pills.

So a company that sells flavanols co-authored a study concluding that you aren’t getting enough flavanols. You can see the shape of it now.

Here’s where the 500-milligram number comes back. Mars Edge sells a supplement called CocoaVia, and its flagship product delivers 500 milligrams of cocoa flavanols per serving. The dose the new study sets as the heart-protective threshold is, to the milligram, the dose in the bottle. The paper never tells you to buy a supplement. It doesn’t have to. It establishes a target almost no one reaches through food, and the company that ran the study happens to sell that exact target in capsule form.

And the load-bearing claim underneath all of it, the reason 500mg is “the heart-protective dose” at all, is the part that made me put my coffee down.

The figure traces back to COSMOS, the Mars-funded randomized trial of about 21,000 older adults. You’ll read everywhere that COSMOS proved cocoa flavanols cut cardiovascular death by 27 percent. The record shows what happened. The trial’s primary endpoint, the main question it was built to answer, total cardiovascular events, came in about 10 percent lower in the flavanol group and missed statistical significance (hazard ratio 0.90, P = 0.11). The headline result the study was designed to deliver did not land. The 27 percent figure is from a secondary endpoint, cardiovascular death, a hazard ratio of 0.73, the kind of result that’s interesting and hypothesis-generating and not at all the same thing as the trial succeeding. When a trial’s main endpoint fails and a secondary one shines, careful scientists call that a lead worth chasing. CocoaVia’s website goes further, advertising a “39% Improvement on important heart health outcomes,” a number you won’t find as the primary result of any single COSMOS analysis.

Watch the sequence, because it’s executed cleanly. Run a large, expensive, legitimately rigorous trial. Watch the primary endpoint come up short. Harvest a positive secondary endpoint, and define its dose as the official “you need this much” threshold. Then publish a second, biomarker-grade study showing that almost nobody reaches the threshold through ordinary eating. Each paper is defensible on its own. Stacked together, they construct a deficiency, and the company that diagnosed it sells the cure.

None of this means the flavanols are useless, and I won’t flatten it into a villain story. The mechanism holds up. The blood-flow effects show up consistently in short-term studies, and a diet heavy in berries, apples, broad beans, and green tea is one I’d recommend to anyone, corporate grant or no. If you want to chase the target through food, the study points at the obvious suspects: blackberries, plums, apples, broad beans, cherries, and green tea, the foods carrying the most flavanols per serving. None of that requires a capsule.

What I don’t trust is the framing. When the entity defining the recommended dose, funding the trial behind the dose, and selling the product that delivers the dose is one and the same, the deficiency it discovers deserves the skepticism you’d bring to a mechanic who finds a new problem with your car on every visit, always one he happens to stock the part for. The biology isn’t the spin. The spin is the quiet slide from “people who eat more flavanols tend to do better” to “you’re deficient and we can fix it.”

So what would I do? Eat the blackberries. Drink the green tea. Skip the bottle until somebody who doesn’t sell flavanols runs the trial that COSMOS’s own primary endpoint never quite delivered. The plants were free the whole time.

Sources

1. Food & Function (RSC), Ottaviani et al., “Adhering to dietary guidelines does not yield flavanol intake levels associated with beneficial cardiovascular effects” (June 8, 2026), DOI 10.1039/D6FO00867D
2. American Journal of Clinical Nutrition, Sesso et al., COSMOS randomized clinical trial of cocoa flavanol supplementation (2022)
3. CocoaVia, “The COSMOS Trial” product/marketing page (Mars Edge)
4. Mars, CocoaVia / Mars Edge flavanol product page
5. ScienceDaily, “Think you’re eating healthy? You may be missing this heart-protecting nutrient” (June 19, 2026)