November 27, 2025

expert reaction to study looking at polyphenol-rich diets and long-term heart health

A study published in BMC Medicine looks at polyphenol rich diets and cardiovascular disease risk. 

Tracy Parker, senior dietician at the British Heart Foundation, said:

“This study adds to the growing body of evidence that diets rich in polyphenols – naturally occurring antioxidants and plant compounds found in foods such as onions, peppers, garlic, nuts, wholegrains, berries, tea, coffee, and olive oil – may help protect heart health over time.

“While the findings are encouraging, it is important to note that the study is observational, meaning further research is needed to confirm these associations, and to understand how other lifestyle factors, such as exercise and medication, may have influenced the results.

“Expanding urine sample analysis to a larger participant group – only 200 samples out of over 3,000 people in the study were tested – would also strengthen findings by providing a clearer picture of how polyphenol intake affects markers of heart health.

“We already know that diet plays a central role in managing risk factors such as high blood pressure, elevated cholesterol, poor blood sugar control, and excess weight – all of which contribute to heart disease.  A healthy diet that supports heart health is one that emphasises diversity: eating a wide range of fruits and vegetables daily, choosing wholegrains over refined grains, incorporating nuts and seeds, and enjoying moderate amounts of tea and coffee.  These foods not only provide polyphenols but also provide fibre, healthy fats, and essential micronutrients that work together to help reduce the risk of heart disease.”

Dr Mark Thomas, Associate Professor of Cardiology and Consultant Cardiologist in Preventive Cardiology, University of Birmingham, said:

“This is a large well-performed observational study that demonstrates that polyphenol-rich diets are associated with lower levels of markers of cardiovascular risk.  The long follow-up time of 11 years is particularly helpful.  Another strength of the study is that it used urinary metabolites of polyphenols in a subset of patients, to make it more quantitative rather than entirely using surveys, which can be unreliable.

“The author’s statement that “a high (poly)phenol-rich diet may substantially slow [cardiovascular risk] progression” suggests causation beyond the level demonstrated in the study, however.

“Although the study looks promising, it was not randomised and patients with a high (poly)phenol diet may have also been more physically active with different medical problems and socioeconomic status compared to those who did not consume that diet.  It is therefore equally possible that these factors, or other factors, are responsible for the beneficial effects seen.

“A critical point to understand is that this study did not investigate whether people actually had fewer heart attacks, strokes or death.  Instead it looked at markers of cardiovascular risk, which may have been largely driven by lower blood pressure.  Whilst this is likely to be beneficial, the effect sizes were relatively small and do not suggest a dramatic effect.  In addition, the study population was almost entirely white female and therefore we do not know whether the results generalise more broadly to more diverse populations.

“Overall, this is a well-performed study that is consistent with broader evidence supporting plant-rich dietary patterns for cardiovascular health.  We now need randomised controlled trials with cardiovascular endpoints (heart attacks, stroke and death) rather than risk scores to establish how beneficial a high (poly)phenol diet is.”

‘Higher adherence to (poly)phenol-rich diet is associated with lower CVD risk in the TwinsUK cohort’ by Yong Li et al. was published in BMC Medicine at 01:00 UK time on Thursday 27 November 2025.

Declared interests

Tracy Parker: “No declarations of interest.”

Dr Mark Thomas: “I don’t have any relevant disclosures for this.”