In a double-blind, placebo-controlled trial with patients suffering from an early form of hypertension (pre-hypertension and stage 1 hypertension), the effect of quercetin on blood pressure was investigated. This dietary supplement led to a reduction in both systolic and diastolic blood pressure. The reduction in diastolic blood pressure was statistically significant (P < 0.01). Please see the study for more details.
Edwards et al.