Effects of hydroxyhydroquinone-reduced coffee on blood pressure in high-normotensives and mild hypertensives

The influence of hydroxyhydroquinone (HHQ) on the antihypertensive effects of chlorogenic acids in coffee was evaluated in a double-blind, randomized controlled trial of high-normotensive and mild hypertensive adult men and women. The subjects were randomly assigned to either an active group that ingested HHQ-reduced coffee (0.05 mg/184 ml) containing chlorogenic acids (299 mg/184 ml) or a control group that ingested coffee containing HHQ (1.69 mg/184 ml) and chlorogenic acids (299 mg/184 ml), corresponding to commercially available products. Each subject was instructed to continuously ingest one can of test beverage (coffee) daily for 12 weeks. A linear mixed-model repeated-measures analysis of covariance of 38 high-normotensives and 60 mild hypertensives showed that systolic blood pressure (SBP) was significantly lower in the active group (n = 51) than in the control group (n = 47) throughout the intake period (Group effect; p = 0.031). A stratified analysis suggested that the antihypertensive effect was greater in the mild hypertensives (Group effect; p = 0.013 in SBP and p = 0.015 in diastolic blood pressure) than in the high-normotensives. Safety assessment revealed no adverse effects associated with the reduction of HHQ to a level lower than the amounts in commercially available coffee products. These results suggest that HHQ-reduced coffee containing chlorogenic acids can be safely ingested to improve hypertension.