Dr. Javier Ottaviani's research team discovered something that upends the standard nutrition advice: eating five portions of fruit and vegetables a day may not be enough to protect your heart. Their study of more than 30,000 people across the UK and United States, published in Food & Function, found that fewer than one in five participants reached the daily intake of flavanols—powerful plant compounds that clinical trials have shown significantly reduce the risk of dying from cardiovascular disease.
The difference between what people eat and what actually protects them comes down to one crucial insight: which five you choose matters far more than simply hitting the number five. Scientists from the University of Reading, Harvard Medical School, the University of California Davis, and Mars, Inc. tracked participants' diets using biomarker measurements and discovered that most people fall well short of 500mg of flavanols daily—the threshold established by the COSMOS study, the largest clinical trial of these compounds. "Most people assume that eating plenty of fruit and vegetables covers this, but what this research shows is that the specific choices you make matter far more than the total amount," Ottaviani explained.
The foods with the highest flavanol concentrations per portion tell a clear story. A 500g serving of plums delivers approximately 450mg of flavanols, nearly meeting the entire daily target in a single food. Cranberries pack about 300mg per 250g serving, while blackberries offer 250mg per 200g portion. A simple cup of green tea contributes around 200mg. Even smaller portions help: broad beans deliver about 140mg per 80g serving, and a medium apple with skin provides 110mg. Cherries, strawberries, and blueberries round out the list with meaningful but lower amounts.
The findings reveal a gap between current dietary guidelines and what science now shows is necessary for real cardiovascular protection. The NHS Eatwell Guide and similar recommendations emphasize portion counts without distinguishing between, say, a handful of blackberries and a handful of strawberries—despite the flavanol difference of 160mg. "Five a day is the right message," said Professor Gunter Kuhnle of the University of Reading, "but we may need to think more carefully about which five."
This research arrives at a moment when dietary science is evolving. Different fruits and vegetables offer vastly different nutritional profiles beyond basic vitamins and minerals. The compounds that protect the heart are not evenly distributed. A person following conventional healthy eating guidance could easily fall short of heart-protective flavanol intake simply by choosing the wrong fruits, even while technically eating well.
What makes this work particularly valuable is its scale and method—tracking real eating patterns across thousands of people in two countries, rather than relying on assumptions about adherence. The biomarker approach captures what people actually absorbed, not just what they ate. That distinction matters because flavanol absorption varies based on how foods are prepared and what else is consumed alongside them.
The implications extend beyond individual choices. If only one in five people eating conventionally reach protective flavanol levels, the standard recommendations may need refinement. Kuhnle suggests the opportunity lies in making dietary guidance "more specific and more effective." That might mean educating people that a cup of green tea alongside their meal could materially improve their heart health outcomes. Or that adding a handful of blackberries to breakfast delivers more cardiovascular benefit than the same portion of blueberries. Strategic choices, not just volume, emerge as the key to turning the five-a-day message into real protection.