NEW ORLEANS — Quaffing three cups of hibiscus tea daily for 6 weeks resulted in a mean 7.2-mm Hg reduction in systolic blood pressure in mildly hypertensive or prehypertensive adults in a randomized, double-blind placebo-controlled trial.
“This suggests that regularly incorporating hibiscus tea into the diet may help control blood pressure in people at risk of developing hypertension,” Diane L. McKay, Ph.D., said at the annual scientific sessions of the American Heart Association.
The public health implications of a blood pressure reduction of this magnitude, if extended to a large population, could be profound. According to the National High Blood Pressure Education Program Coordinating Committee, a mere 3-mm Hg reduction in systolic blood pressure (SBP) would reduce the relative risk of death due to stroke by 8%, due to coronary artery disease by 5%, and all-cause mortality by 4% (JAMA 2002;288: 1882-8), said Dr. McKay, of the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston.
She reported on 65 prehypertensive or mildly hypertensive adults who took part in a 6-week double-blind study in which they consumed three 8-ounce cups of hibiscus tea daily or a placebo beverage similar in color and taste.
Mean SBP dropped by 7.2 mm Hg in the herbal tea group from a baseline of 129.4 mm Hg, compared with a 1.3-mm Hg decline in the control group. Diastolic blood pressure (DBP) fell by a mean of 3.1 mm Hg from a baseline of 78. 9 mm Hg and mean arterial pressure dropped by 4.5 mm Hg from 95.7 mm Hg at enrollment, although neither of these changes achieved statistical significance.
However, the tea's antihypertensive effect increased with higher baseline blood pressure. In the half of subjects whose SBP exceeded 129 mm Hg, mean SBP reduction after 6 weeks of hibiscus tea consumption was 13.2 mm Hg, and the reductions of 6.4 mm Hg in DBP and 8.7 mm Hg in mean arterial pressure were also statistically significant.
The intervention had no side effects or downsides, said Dr. McKay.
Dr. Robert H. Eckel observed that the blood pressure reduction seen with hibiscus tea in this trial is equal to the typical effect of a single antihypertensive medication.
But although the notion of the tea as a nutraceutical for blood pressure lowering is intriguing, a larger confirmatory study with longer follow-up is needed, said Dr. Eckel, past president of the AHA and professor of medicine, physiology, and biophysics, and program director of the adult general clinical research center at the University of Colorado, Denver.
Dr. McKay and coworkers conducted their randomized trial because earlier animal studies suggested Hibiscus sabdariffa L. has antihypertensive and antiatherosclerotic effects. Hibiscus contains flavinoids and phenolic acids which have potent antioxidant properties. The study was supported by the Agricultural Research Service of the U.S. Department of Agriculture and by Celestial Seasonings.
To view a video interview of Dr. McKay, go to http://www.youtube.com/familypracticenews
Regularly incorporating hibiscus tea into the diet may help control blood pressure. DR. MCKAY
The tea had the greatest effect in thosewith higher baseline blood pressure. ©Monika Adamczyk/