The six month study – published in JAMA’s Archives of Internal Medicine– reports that people who drink black tea throughout the day may benefit from slight reductions in blood pressure.
The research team, led by Professor Jonathan Hodgson from the University of Western Australia (UWA), revealed that regular consumption of three or more cups of black tea per day (supplying approximately 429 miligrams per day of polyphenols – resulted in subtle yet significant decreases in diastolic and systolic blood pressure (BP).
“Our study has demonstrated for the first time to our knowledge that long-term regular consumption of black tea can result in significantly lower BPs in individuals with normal to high-normal range BPs,” said Hodgson and his team.
“At a population level, the observed differences in BP would be associated with a 10% reduction in the prevalence of hypertension and a 7% to 10% reduction in the risk of cardiovascular disease,” they revealed.
The research group, made up of scientists from UWA, Unilever, and the National Health and Medical Research Council of Australia, said that after the six-month trial period tea drinkers’ systolic and diastolic blood pressure fell between 2–3mm Hg compared to non-tea drinkers.
"This is a hugely exciting development for us," said Jane Rycroft, senior nutrition and health manager at Unilever's Research & Development.
"This is further evidence to suggest that tea and its natural ingredients can help people become healthier. While a 2-3 mm Hg decrease is a small change to an individual's blood pressure, it's tantalising to think what positive impact this could have on reducing the risk of heart disease among the general public," she said.
Hodgson and his team recruited 95 Australian participants aged between 35 and 75. They were randomised to drink either three cups of black tea or another beverage similar in taste and caffeine content, but not derived from tea, daily for six months.
After the six month period the research found that the tea drinkers' systolic (top number) and diastolic (bottom number) blood pressure fell between 2 and 3 mm Hg compared to non-tea drinkers.
They added that whilst the results showed a subtle lowering of blood pressure, which in itself may offer benefits at the population level, “it is also possible that longer-term regular consumption of black tea is needed for larger falls in blood pressure to become apparent.”
"High blood pressure can significantly impact people's risk of developing cardiovascular disease, so this is a very significant discovery," Hodgson explained.
"There is already mounting evidence that tea is good for your heart health, but this is an important discovery because it is evidence of a link between the two," he added.
Source: Archives Internal Medicine
Vol. 172 No. 2, Pages 186-188, doi:10.1001/archinte.172.2.186
“Effects of Black Tea on Blood Pressure: A Randomized Controlled Trial”
Authors: J.M. Hodgson, I.B. Puddey, R.J. Woodman, T.P.J. Mulder, D. Fuchs, K. Scott, K.D. Croft