And those with the highest systolic blood pressure readings at the start of the study (129 or above) had a greater response to hibiscus tea.
AHA nutrition scientist Diane McKay delivered the paper from the Antioxidants Research Laboratory of the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University in Boston to the AHA’s annual conference in New Orleans.
The government and business co-funded study tested 65 volunteers aged 30 to 70 years whose systolic blood pressure was 120 to 150mm/Hg and whose diastolic blood pressure was 95 mm/Hg or less when the study began.
Blood pressure readings of 120 over 80 or greater are considered a risk factor for heart disease, stroke and kidney disease.
The 65 volunteers were split into two groups with one drinking three cups of hibiscus tea per day for six weeks. The other group was administered a placebo beverage containing artificial hibiscus flavouring and colour.
Participants followed regular dietary and physical activity patterns and their blood pressure was measured weekly.
Those who drank hibiscus tea had a 7.2 per cent drop in their systolic blood pressure, compared to a 1.3 per cent drop in the placebo group.
Those with the highest systolic blood pressure (129 and above) saw their systolic blood pressure drop 13.2 per cent, and diastolic blood pressure went down by 6.4 per cent. In this sub-group, mean arterial pressure went down by 8.7 per cent.
Hypertension, or chronically high blood pressure, affects one third of US adults.
The blood pressure study was funded by the Agricultural Research Service, a scientific research agency of the US Department of Agriculture, along with Colorado-based food maker, Hain Celestial Group.
Despite the positive results, the AHA said further study was required if the hibiscus/blood pressure benefits are to be quantified over the long-term.
French hibiscus extract supplier, Burgundy Botanical Extracts, welcomed the results but noted its own investigations revealed hibiscus could only affect blood pressure when taken at daily doses of 3-5 grams, a level not compatible with most food matrices.
Hibiscus is found in most tea blends in North America, but at low levels.
“We are investigating different effects and matrices and expect to complete some research in mid-2009,” sales and marketing director, Gontran Gaillot, told NutraIngredients.com. Male kidney health was one area being investigated.
Burgundy has been building awareness around the ingredient on the back of science supporting its ability to benefit urinary tract infections (UTIs) and to function as a diuretic.