King’s College London has just released a groundbreaking study tracking over 3,100 people for more than 11 years. What makes it different? Instead of guessing polyphenol intake from food questionnaires, researchers mapped real polyphenol-rich eating habits and matched them with urinary metabolites—offering the clearest link yet between these powerful plant compounds and heart disease risk.
The findings come from the TwinsUK cohort, an ongoing study of British twins that has been running for more than 30 years. For this analysis, researchers tracked 3,110 participants (average age 52 at baseline, predominantly female) over roughly 11.2 years, making it one of the most comprehensive long-term datasets available for evaluating diet and cardiometabolic health.
They found that higher adherence to polyphenol-rich dietary patterns were inversely associated with cardiovascular disease risk scores.
For many health professionals this will be no surprise, but this study is interesting because the polyphenol dietary score (PPS) takes a different approach. Instead of counting milligrams, it essentially asks - how often and how much do you eat from a list of 20 polyphenol-rich whole foods. Higher polyphenol dietary scores (PPS) were negatively correlated with atherosclerotic cardiovascular (ASCVD) risk scores and HeartScore measurements. This pattern-based approach better captures the synergistic effects of polyphenols consumed as whole foods, the diversity of polyphenol types, and overall diet quality. This dual approach of dietary questionnaire and urinary metabolites (in a subset of 200 participants) provides complementary evidence, with the biomarkers offering objective validation of self-reported intake.
The PPS was based on the relative intake of 20 polyphenol-rich foods, including tea, coffee, red wine, wholegrains, breakfast cereals, chocolate and cocoa products, berries, apples and apple juice, pears, grapes, plums, citrus fruits and citrus juice, potatoes and carrots, onions, peppers, garlic, green vegetables, pulses, soybeans, nuts, and olive oil. Participants were scored on their consumption of each food group - those eating the most of each food received 5 points, while those eating the least received 1 point, with scores then totalled across all 20 food groups.
A subset of 200 participants’ urine samples were analysed to measure 114 different polyphenol metabolites using advanced laboratory techniques (UHPLC-MS). This provided an objective biomarker of polyphenol exposure that was independent of self-reported dietary intake - effectively validating participants’ reported diets with measurable evidence of what their bodies actually absorbed and metabolised.
Understanding the Key Polyphenol Classes
The study identified specific polyphenol subclasses that showed the strongest associations with cardiovascular benefits. Both flavonoids and phenolic acids in the urinary metabolites correlated with reduced CVD risk. For phenolic acids specifically, coffee, tea, and red wine were key sources, while berries contributed significantly to both phenolic acid and flavonoid metabolite profiles - particularly anthocyanins, the pigments responsible for their vibrant colours.
When researchers analysed the urinary metabolites, they found compelling patterns. Individuals with elevated urinary flavonoids, phenolic acids, and tyrosols (predominantly from olive oil) showed correlations with multiple cardiovascular benefits: lower diastolic blood pressure, reduced cardiovascular risk scores, and higher HDL cholesterol levels. The fact that these benefits were detected through urinary metabolites rather than just dietary recall adds credibility to the dietary pattern approach and suggests these polyphenols are biologically active in the body.
Clinical Implications
For many nutritional health practitioners, this research provides robust scientific validation for what we're already doing in clinical practice. The practical application remains straightforward: encourage patients to regularly incorporate a variety of polyphenol-rich whole foods into their daily eating patterns. Patients who consume tea or coffee, include berries and other fruits in their diets, use olive oil, eat wholegrains and pulses, and incorporate vegetables like onions, peppers, and leafy greens are naturally following a heart-protective dietary pattern. This aligns perfectly with evidence-based approaches like the Mediterranean diet that are already recommended.
What makes this study particularly valuable is the strength of its methodology - validating dietary intake with objective urinary biomarkers gives us greater confidence in explaining to patients why these dietary patterns translate into measurable cardiovascular benefits. It's evidence we can point to when patients question whether these fundamental dietary recommendations really make a difference.
Practical Ways to Boost Polyphenol Intake in Clinical Practice
Looking for simple, actionable strategies to help clients increase their polyphenol-rich food consumption? Here are five easy wins:
1. Berry boost shortcuts - Recommend freeze-dried berry powders like haskap (exceptionally high in anthocyanins) to stir into yoghurt, porridge, or smoothies - no washing, chopping, or worrying about fresh berries going off
2. The olive oil drizzle habit - Encourage clients to finish cooked dishes with a drizzle of extra virgin olive oil rather than cooking with it, preserving the heat-sensitive polyphenols including hydroxytyrosol
3. Herb and spice volume - Fresh herbs aren't just garnishes - suggest using them by the handful. Parsley, oregano, and thyme are polyphenol powerhouses that can transform a meal's nutritional profile
4. The tea swap - For coffee-only drinkers, suggest alternating with green or black tea to diversify their polyphenol intake and add different flavonoid subclasses (particularly catechins from green tea)
5. Nuts as a daily non-negotiable - Rather than occasional snacking, recommend a small daily portion (30g) of mixed nuts, which provides not just polyphenols but also supports the absorption of fat-soluble polyphenols from other foods in the diet.
REFERENCES
Li, Yong, et al. “Higher Adherence to (Poly)Phenol-Rich Diet Is Associated with Lower CVD Risk in the TwinsUK Cohort.” BMC Medicine, vol. 23, no. 1, 2025, p. 645, pubmed.ncbi.nlm.nih.gov/41299455/, https://doi.org/10.1186/s12916-025-04481-5.