Effects of hydroxyhydroquinone-reduced coffee on vasoreactivity and blood pressure.

Recent studies suggest that chlorogenic acids, which are the main components of the polyphenol class in coffee, decrease blood pressure, and that hydroxyhydroquinone (HHQ), which is generated by roasting coffee beans, inhibits the antihypertensive effect of chlorogenic acids in brewed coffee. Here, we examined the vasoreactivity and antihypertensive effects of HHQ-reduced coffee in mild hypertension. The study design was a double blind, randomized, placebo-controlled intervention study, with a 4-week run-in period, followed by an 8-week test beverage ingestion period. The subjects were Japanese men and women with mild hypertension and vascular failure, who were not taking any antihypertensive drugs. During the test beverage ingestion period, the subjects ingested either active or placebo HHQ-reduced coffee (chlorogenic acids per 184 ml of coffee: active, 300 mg; and placebo, 0 mg) daily. Subjects were randomly divided into two groups: active group (n=9) and placebo group (n=12). In the active beverage group, endothelium-dependent, flow-mediated vasodilation impairment was significantly ameliorated and systolic blood pressure was significantly decreased from the baseline, but not in the placebo group. There were no test beverage consumption-related changes in other parameters that may influence blood pressure, such as pulse, cardiac output, body weight or 24-h urine volume. Ingestion of the active beverage significantly decreased urinary isoprostane levels, suggesting a reduced oxidative stress. These findings indicate that HHQ-reduced coffee decreased blood pressure in subjects with mild hypertension. The decreased blood pressure was associated with improved vascular endothelial function.