Eating five servings of fruits and vegetables per day does not always protect your heart. A study involving more than 30,000 participants shows that fewer than one in five reach the flavanol intake needed to reduce cardiovascular disease risk — even when following standard nutritional guidelines. The precise choice of foods matters far more than their sheer quantity.
What you will learn
- Why following the five-a-day rule does not guarantee an adequate intake of protective flavanols
- Which specific foods concentrate the most flavanols per serving—and which ones are surprisingly at the top
- What this finding could change in future official nutrition guidelines
Inadequate intake despite a “balanced” diet
A study conducted by researchers from the University of Reading, Harvard Medical School, the University of California, Davis, and Mars, Inc., published in Food & Function, tracked the diets of more than 30,000 participants in the United Kingdom and the United States using precise biomarkers.
The finding is striking: fewer than one in five achieve the flavanol intake associated with a meaningful reduction in cardiovascular risk — including among those who regularly consume the recommended five portions of fruits and vegetables daily.
Why quantity is not enough
According to Dr. Javier Ottaviani, the study’s lead author, flavanols can substantially reduce the risk of death from cardiovascular disease — but only if consumed in sufficient amounts. Most people assume that a diet rich in fruits and vegetables in general is enough. This research shows the opposite: the specific food choices matter far more than the total volume consumed.
The COSMOS study, the largest clinical investigation on flavanols to date, had already established that a daily intake of 500 mg significantly reduces the risk of death from heart disease. Yet the new study reveals that the vast majority of people stay well below this threshold, even when following official dietary guides such as the British Eatwell Guide.
The ranking of the flavanol-rich foods
Some results are surprising relative to the common ideas about “superfoods.” Prunes come out on top with about 450 mg of flavanols per 500 g, followed by cranberries (300 mg per 250 g) and blackberries (250 mg per 200 g). Green tea provides around 200 mg per 250 ml cup — a beverage often overlooked in conventional fruit-and-vegetable guidelines.
Beans, cherries, and apples with skin follow, contributing roughly 140, 130, and 110 mg respectively. Strawberries and blueberries, frequently regarded as antioxidant benchmarks, actually supply only 90 and 80 mg respectively — less than one might expect given their nutritional reputations.
Toward more precise recommendations
Professor Gunter Kuhnle of the University of Reading notes that the idea of five fruits and vegetables per day remains relevant, but a finer consideration is needed of the exact composition of those five portions. Different fruits and vegetables offer highly varied nutritional benefits beyond the vitamins and minerals traditionally highlighted.
As scientific understanding of these bioactive compounds deepens, this research paves the way for more specific dietary guidelines — not only focusing on the amount of fruit and vegetables consumed, but on their precise content of compounds beneficial to cardiovascular health.
