Herbal tea containing hibiscus may modestly lower blood pressure in prehypertensive and mildly hypertensive patients, researchers found.
Hibiscus-based tea reduced systolic blood pressure by 7.2 mm Hg, on average, over six weeks of daily intake, a significant reduction compared with the 1.3-mm Hg decline with placebo (P0.03), Diane L. McKay, Ph.D., of Tufts University in Boston, and colleagues reported here at the American Heart Association meeting.
In the small, randomized trial, patients with blood pressure higher than 129 mm Hg had significantly greater benefits for systolic, diastolic, and mean arterial pressure.
Even relatively small blood pressure changes like those seen in the study would likely have an impact on patient outcomes if maintained over time, Dr. McKay said.
Explain to interested patients that the study was relatively small and would need validation before hibiscus-containing tea could be recommended clinically.
Note that this study was published as an abstract and presented orally at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.
To prove her point, she noted that a 3 mm Hg decline in systolic pressure reduced the relative risk of stroke mortality by 8%, coronary artery disease mortality by 5%, and all-cause mortality by 4% in a population-based study reported in the Journal of the American Medical Association in 2002.
“Whether this type of behavior can be sustained, whether the blood pressure effect can be sustained ultimately in outcomes studies is open to speculation,” said Robert H. Eckel, M.D., of the University of Colorado Denver, who moderated a press conference at which the findings were presented.
But, he said, the magnitude of the antihypertensive effect was similar to standard blood pressure medications.
The idea of hibiscus tea as a nutraceutical is worthy of validation and further study, Dr. Eckel said.
Hibiscus is one of the most common components of herbal teas, contributing a fruity, tart taste and red color, Dr. McKay said. It contains anthocyanins, flavones, flavonols, and phenolic acids and has been shown in animal studies to reduce atherosclerosis and blood pressure, she said.
So, her group conducted a placebo-controlled randomized trial to see whether these effects were significant in humans.
The study included 65 healthy men and women ages 30 to 70 who were prehypertensive or mildly hypertensive (systolic 120 to 150 mm Hg, diastolic 95 mm Hg or lower) and not taking any blood pressure medications.
Patients were randomized to three 8-oz cups of herbal tea a day, brewed with one tea bag for six minutes or to a placebo containing artificial hibiscus flavor and color. These could be consumed at any time of day, hot or cold, with sweetener or milk according to patient preference.
After six weeks of treatment, systolic blood pressure dropped 7.2 mm Hg with hibiscus tea (P0.01 versus baseline) compared with a 1.3 mm Hg reduction among placebo-treated patients from a mean of 129.4 and 129.8 mm Hg at baseline, respectively (P0.03).
Diastolic pressure also declined in the tea-treated patients, although the difference was significant only for change from baseline (-3.1 mm Hg, P0.01) and not in comparison with the 0.5 mm Hg decline seen in the placebo group.
The fall in mean arterial pressure with hibiscus tea tended toward significance as well (change from baseline -4.5 versus -0.8 mm Hg, P=0.054).
The effect increased over time for systolic but not diastolic pressure, and was greatest for those with higher blood pressures.
Among those with a systolic pressure greater than 129 mm Hg, the reduction was almost double that in the overall cohort and was significant compared with placebo for every measure of hypertension. These findings included:
A 13.2 mm Hg reduction in systolic blood pressure compared with a 1.3 mm Hg reduction with placebo (P0.01 versus baseline, P0.02 versus placebo)
A 6.4 mm Hg reduction in diastolic pressure compared with a 1.3 mm Hg increase with placebo (P0.01 versus baseline, P0.02 versus placebo)
An 8.7 mm Hg drop in mean arterial pressure compared with a 0.4 mm Hg increase with placebo (P0.01 versus baseline, P0.02 versus placebo)
While cautioning that the study was relatively small and would need validation, Dr. McKay suggested that incorporating hibiscus tea into the diet on a regular basis may help control blood pressure in people at risk of developing hypertension.
The study was funded by Celestial Seasonings of the Hain Celestial Group, which makes hibiscus-containing teas, and the Department of Agriculture under a cooperative agreement.