Effects of Acute Oral Administration of <i>Hibiscus sabdariffa</i> Tea on Blood Pressure and Pulse Rate in Apparently Healthy Humans: A Randomized Double-blind Placebo-controlled Study

Abstract

Background: Although evidence suggests that acute ingestion of the aqueous calyx extract of Hibiscus sabdariffa inhibits sympathetic nervous system  activity, it is not known if this effect is associated with a fall in blood pressure (BP). This study therefore investigated the acute effect of Hibiscus sabdariffa  tea (HST) on BP and pulse rate using a randomized double-blind, placebocontrolled design.

Methods: Following ethical approval and informed consent, the BP and pulse rate of apparently healthy subjects were measured before (basal) and one  hour after the oral administration of 200mg/kg HST (n=20) or a food colourant (16ml/L; n=20) that served as placebo. The change (Δ) in these parameters  was obtained by subtracting the basal values from the values obtained in the presence of Hibiscus sabdariffa tea or placebo. The results are expressed as  mean ± SEM. P<0.05 was considered significant.

Results: In the presence of Hibiscus sabdariffa tea, the systolic blood pressure (SBP; 106.5±3.0mmHg) fell significantly (P<0.05) compared to the basal value (116.7±2.9mmHg), while the diastolic blood pressure (DBP); mean arterial pressure (MAP) and pulse  rate (PR) showed no significant difference. In the presence of the placebo, the blood pressure parameters (SBP, DBP and MAP) and PR showed no  significant difference from the basal values. However, in the presence of Hibiscus sabdariffa tea, the changes (Δ) in blood pressure parameters and PR were significantly (P<0.0001) lowered, compared to the change induced by the placebo.

Conclusion: It is concluded that acute consumption of Hibiscus  sabdariffa tea lowers blood pressure and pulse rate in normotensive subjects.