For years, health experts have encouraged people to eat at least five portions of fruit and vegetables each day.
This advice has been promoted around the world because fruits and vegetables contain vitamins, minerals, fiber, and many other nutrients that help protect health.
In the United Kingdom, the National Health Service recommends eating five 80-gram portions daily, a message that has become widely known as “five a day.” Many people assume that as long as they reach this target, they are getting everything they need from plant foods.
However, a new study suggests the story may be more complicated. Researchers have found that the specific fruits and vegetables people choose may be just as important as the total amount they eat.
The study indicates that many people are missing out on natural compounds called flavanols, which may play an important role in protecting the heart and blood vessels.
Flavanols are natural substances found in certain fruits, vegetables, beans, tea, and other plant foods. Scientists have been studying these compounds for many years because they appear to help blood vessels function properly and may support healthy circulation.
Some research suggests that flavanols can improve blood flow, reduce inflammation, and lower the risk of cardiovascular disease.
The new research was conducted by scientists from the University of Reading, Harvard Medical School, the University of California Davis, and Mars, Inc.
The team examined dietary information from more than 30,000 people living in the United Kingdom and the United States. Instead of relying only on food questionnaires, the researchers also used biological measurements that can estimate flavanol intake more accurately.
Their findings revealed a surprising problem. Even among people who regularly ate five portions of fruits and vegetables each day, fewer than one in five consumed enough flavanols to reach levels previously linked to better heart health.
According to the researchers, this means that following general dietary advice may not automatically provide enough of these potentially beneficial compounds. The types of foods chosen matter greatly because flavanol levels vary enormously between different fruits and vegetables.
Dr. Javier Ottaviani, the lead author of the study, explained that flavanols have been associated with a lower risk of dying from cardiovascular disease, but only when people consume sufficient amounts.
He noted that many people assume eating plenty of fruits and vegetables automatically provides enough flavanols, but the new findings suggest that this is not always true.
Some foods were found to be particularly rich sources of flavanols. Green tea ranked among the highest. Certain fruits such as plums, blackberries, apples, cherries, cranberries, strawberries, and blueberries also provided meaningful amounts. Broad beans and pinto beans were additional sources.
The findings build on earlier research, including the large COSMOS clinical trial. That study found that approximately 500 milligrams of flavanols per day was associated with a significant reduction in the risk of dying from heart disease. Yet the new analysis suggests that most people consume much less than that amount.
This raises important questions about current dietary recommendations. Public health advice has traditionally focused on increasing the overall consumption of fruits and vegetables.
While that guidance remains valuable, researchers suggest that future recommendations may also need to highlight foods that provide specific health-promoting compounds.
Professor Gunter Kuhnle from the University of Reading said that the message of eating five portions daily remains important. However, he noted that different fruits and vegetables offer different nutritional benefits. As scientists learn more about compounds such as flavanols, dietary advice may become more detailed and personalized.
The study has several strengths. It included a very large number of participants and used biological markers rather than relying solely on self-reported food intake. This improves confidence in the findings.
However, the research also has limitations. It cannot prove that increasing flavanol intake alone will directly prevent heart disease. Many factors influence cardiovascular health, including exercise, smoking, body weight, genetics, and overall diet quality.
Overall, the findings suggest that eating a variety of flavanol-rich foods may be an easy way to support heart health. The study highlights that healthy eating is not only about quantity but also about food choices.
Future research will help determine whether dietary guidelines should place greater emphasis on specific fruits, vegetables, and beverages that provide higher levels of flavanols.
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The research was published in the journal Food & Function.
Source: University of Reading.
