Effects of a quercetin-rich onion skin extract on 24 h ambulatory blood pressure and endothelial function in overweight-to-obese patients with (pre-)hypertension: a randomised double-blinded placebo-controlled cross-over trial.

Abstract in brief

• The study investigated whether quercetin, a polyphenol found in onion skin extract, can lower blood pressure and improve blood vessel function in overweight or obese people with prehypertension or stage I hypertension.
• Results showed that quercetin did not significantly change blood pressure in the overall group, but it did lower 24-hour systolic blood pressure by about 3.6 mmHg in hypertensive patients, especially during day and night periods.
• The study found no significant effects of quercetin on various biomarkers or endothelial function measures, suggesting that its blood pressure-lowering effect may involve mechanisms not captured by these biomarkers.]