In vitro studies show Hibiscus sabdariffa L., an ingredient found in many herbal tea blends and other beverages, has antioxidant properties, and, in animal models, extracts of its calyces have demonstrated hypocholesterolemic and antihypertensive properties.

 

The objective of this study—conducted at USDA Human Nutrition Research Center on Aging at Tufts University in Boston, MA—was to examine the antihypertensive effects of H. sabdariffa tisane (hibiscus tea) consumption in humans.

 

A randomized, double-blind, placebo-controlled clinical trial was conducted in 65 pre- and mildly hypertensive adults, age 30–70, not taking blood pressure-lowering medications, with either three 240-mL servings/day of brewed hibiscus tea or placebo beverage for 6 weeks. A standardized method was used to measure BP at baseline and weekly intervals.

 

At 6 weeks, hibiscus tea lowered systolic BP (SBP) compared with placebo. Diastolic BP was also lower, although this change did not differ from placebo. The change in mean arterial pressure was of borderline significance compared with placebo. Participants with higher SBP at baseline showed a greater response to hibiscus treatment. No effects were observed with regard to age, gender, or dietary supplement use.