Background: Hibiscus sabdariffa (HS) is widely consumed in Nigeria as a refreshing beverage and also as an antihypertensive agent. Since three decades ago when its antihypertensive activities were reported in several animal experiments, its consumption has greatly increased.
Aim: The aim of this study is to investigate the effect of HS consumption on blood pressure (BP) and electrolytes of mild to moderate hypertensive Nigerians and compare it with that of hydrochlorothiazide (HCTZ), a diuretic widely used as first-line antihypertensive drug.
Subjects and methods: Eighty newly diagnosed, but untreated mild to moderate hypertensive subjects attending Medical Out-Patients clinic of Enugu State University Teaching Hospital, Enugu, were recruited for the study. They were randomly divided into three groups: A, B and C. Those in Groups A were given placebo; those in Group B took HCTZ while those in Group C were given HS. Treatment lasted for 4 weeks. BP, serum, and urine electrolytes were measured at baseline, weekly during treatment and 1 week after withdrawal of treatment.
Results: At the end of treatment, both HCTZ and HS significantly (P<0.001) reduced systolic BP, diastolic BP, mean arterial pressure and serum Na+ compared to placebo. When compared to each other, HCTZ significantly (P<0.001) reduced serum Na+ and Cl- compared to HS and significantly (P<0.001) increased K+ and Cl- output in urine. After withdrawal of treatment, the fall in BP and serum Na+ in HS group were significant compared to HCTZ where they returned to baseline values. No side effect was reported during the study.
Conclusion: HS was a more effective antihypertensive agent than HCTZ in mild to moderate hypertensive Nigerians and did not cause electrolyte imbalance. HS showed longer duration of action compared to HCTZ and reduction in serum Na+ may be another antihypertensive mechanism of action of HS.