Black Tea’s Blood Pressure Effect May Take Time

January 9, 2013

Blood pressure support may require months of drinking black tea.

Previously published research supports consumption of black tea for blood pressure support, including a recent six-month trial where 95 adults drank a polyphenol-rich black tea or placebo and tea drinkers experienced lower systolic and diastolic blood pressure. But results of a new study-by the same team of researchers-suggest that short-term black tea consumption isn’t enough to lower blood pressure.

The study is published in the journal Food & Function.

Researchers from the University of Western Australia assigned 111 adults to three cups of black tea for four weeks daily or placebo. At the end of this intervention, subjects then consumed three cups of powdered black tea solids (containing 429 mg of polyphenols) or a control beverage matched for flavor and caffeine levels. Blood pressure and heart rate readings taken at four weeks and after the 24-hour intervention revealed no significant changes for blood pressure and mixed results for heart rate.

In light of the results and those of their previous study, the researchers concluded that the significant blood pressure reductions observed with black tea consumption “are unlikely to be due to short-term changes.”