Black Tea Lowers Blood Pressure
High blood pressure (BP) is a leading risk factor contributing to the global burden of disease. Small changes in BP due to dietary modification may have a significant impact on the prevalence of hypertension and risk of cardiovascular disease.
Dr Jonathan Hodgson (University of Western Australia, Perth) and colleagues reported in the Archives of Internal Medicine that regular consumption of black tea reduced systolic and diastolic blood pressure between 2 to 3 mm Hg
In their study, the group randomized 95 men and women with a daytime ambulatory systolic blood pressure between 115 and 150 mm Hg to three cups of black tea daily or to placebo that matched the tea in flavor and caffeine content (approximately 96 mg of caffeine per day). There were no significant differences between patient groups at baseline.
Daily consumption of the tea resulted in a significantly lower 24-hour systolic and diastolic blood pressure compared with the control arm. The net-effect difference in systolic blood pressure at three and six months was -2.7 mm Hg and -2.0 mm Hg, respectively (p=0.006 at three months, p=0.05 at six months). Diastolic blood pressure was reduced 2.3 mm Hg and 2.1 mm Hg at three and six months, respectively (p<0.001 at three months, p=0.003 at six months).
Black tea is a common source of flavonoids, which have been suggested to contribute to vascular health. The researchers point out that they have shown that flavonoids augment nitric-oxide status and reduce plasma concentration of endothelin-1, both of which could contribute to reductions in vascular tone and reduced blood pressure.
Hodgson JM, Puddey IB, Woodman RJ, et al. Effects of black tea on blood pressure: A randomized controlled trial. Arch Intern Med 2012; 172:186-188.