Flavonoid-rich foods: a possible vascular benefit, not proof of cardiovascular prevention

What the researchers compared

The systematic review brings together 11 randomized trials comparing consumption of flavonoid-rich foods with control groups in healthy adults. The literature search covers studies available up to June 10, 2026, and includes a search for unpublished trials on ClinicalTrials.gov.

The abstract consulted reports a risk-of-bias assessment using the Cochrane RoB 2.0 tool. However, it does not detail the foods tested, doses, intervention durations, or composition of the control groups. This document alone cannot identify a food or quantity to prioritize.

A measurable but variable improvement

The main finding concerns flow-mediated dilation, an indicator of an artery’s response to increased blood flow. The mean difference between groups is 1.58 percentage points in favor of flavonoid-rich foods, with a 95% confidence interval ranging from 0.90 to 2.27 points.

This result is statistically significant, but heterogeneity is high: I² reaches 75.7%. The trials therefore do not all show effects of the same magnitude. The pooled average is not a promise of individual benefit.

Carotid-femoral pulse wave velocity, a marker of arterial stiffness, also changes in a favorable direction. However, this finding does not hold up in some sensitivity analyses. The signal is therefore less robust.

Finally, no statistically significant difference is observed in systolic or diastolic blood pressure. This does not prove a complete absence of an effect, but it does not support a claim that these interventions lower blood pressure.

What this means for your diet

These data support a possible effect of flavonoid-rich foods on certain markers of vascular function in healthy people. They demonstrate neither a reduction in heart attacks or strokes nor an equivalent benefit in people with cardiovascular disease.

They also do not justify applying the result to a concentrated supplement. The authors call for larger trials to clarify the relevant flavonoid subclasses, doses, and durations. At this stage, the review sheds light on a nutritional avenue, not a protocol.

What we can take away

The most convincing signal concerns arterial dilation, with results varying across trials. A better biomarker is not enough to demonstrate cardiovascular prevention.