Is the antihypertensive activity of Hibiscus sabdariffa affected by factors such as origin of the plant and time of decoction? Implications for clinical practice.

Hibiscus sabdariffa is effective against hypertension in clinical trials, with a dose-response effect, making it an important, accessible and sustainable treatment. The aim of the present work was to clarify the influence of origin of Hibiscus on clinical effect and decoction time on the yield of active substances, in order to issue recommendations for use. This study reviewed blood pressure progress in three clinical trials after 3-4 weeks of Hibiscus tea consumption, with batches analyzed for total anthocyanins (TA) and hibiscus acid (HA), the 2 known active substances, with two different decoction times (10 vs 20 min). HA levels appeared consistent across batches for a given decoction time, whereas TA levels varied up to 4-fold. Despite this variation, clinical outcomes remained similar. Quantities of TA extracted increased with a longer decoction time. These results suggest that the batch of Hibiscus does not significantly influence its antihypertensive activity, and that HA is a main active principle. Thus, a future perspective of this work could be the development of a more available method, other than NMR, for the characterization of the HA content. Clinical practice should involve adjusting Hibiscus dosage based on individual BP response. Starting treatment with, instead of 10 g, 2.5 g/day and adjusting as needed is recommended, and a 20 min decoction remains advisable. HS decoctions can be recommended for broad BP control thanks to their safety and effectiveness.