Study finds many heart-healthy diets still miss key flavanols

A plate that looks healthy is not always delivering the compounds linked to heart protection. New research led by the University of Reading found that many adults who met standard fruit-and-vegetable advice still missed flavanols, the plant compounds associated with lower cardiovascular risk.

The study examined dietary data from more than 30,000 people in the United Kingdom and the United States, using validated urinary biomarkers to estimate flavanol intake. It drew on two large cohorts, COSMOS with 6,509 participants and EPIC-Norfolk with 24,154 participants. Fewer than one in five participants reached the intake level tied to benefit: 19.2% of COSMOS participants and 17.9% of EPIC-Norfolk participants hit a biomarker-estimated intake of at least 500 mg a day.

The gap persisted even among people who appeared to follow official dietary guidance. The paper said fewer than 25% of participants meeting dietary guidelines achieved an estimated flavanol intake of at least 500 mg a day. That finding matters because the research team said a daily intake of 500 mg of flavanols was associated with reduced risk of dying from heart disease.

The difference, the researchers said, came down less to total produce and more to the kind of produce on the plate. Foods and drinks highlighted as higher in flavanols included blackberries, plums, apples, broad beans, cherries and green tea. The implication is that a person can eat the recommended amount of fruits and vegetables and still fall short if those choices are low in flavanols.

The study involved scientists from the University of Reading, Harvard Medical School, the University of California Davis and Mars, Inc., and it was published in Food & Function. Lead researcher Javier Ottaviani said flavanols can significantly reduce cardiovascular risk, but only if people eat enough of them, underscoring that specific choices matter more than the total amount of produce.

The findings also drew support from COSMOS, a randomized, double-blind, placebo-controlled trial of cocoa extract supplements containing 500 mg a day of cocoa flavanols. COSMOS focused on women aged 65 and older and men aged 60 and older and is described as the first large-scale randomized trial testing long-term flavanol supplementation for prevention of cardiovascular disease and cancer. The researchers said similar patterns appeared in EPIC-Norfolk and in simulations using fruits and vegetables commonly eaten in the U.S. diet.

For doctors, dietitians and consumers, the message is precise rather than punitive: five-a-day still helps, but it is not a guarantee of flavanol intake. If further studies keep linking flavanols to long-term cardiovascular outcomes, the result could shape food labeling and future dietary guidance around which fruits, vegetables and beverages actually deliver the benefit.