A six month study by scientists at the University of Western Australia (UWA), Unilever and the National Health and Medical Research Council of Australia suggests that people who drink black tea throughout the day may get the benefit of a slight reduction in their blood pressure. Funding for the study was provided by the National Health and Medical Research Council of Australia and Unilever Research and Development, Vlaardingen, The Netherlands.
Before the study started, the participants' blood pressure throughout the day was about 121/72 millimeters of mercury (mm Hg). Blood pressure readings less than or equal to 120/180 mm Hg are considered normal.
The research, now published in the Archives of Internal Medicine(1), is the first of its kind to show that drinking black tea may have this effect.
"High blood pressure can significantly impact people's risk of developing cardiovascular disease, so this is a very significant discovery," said Professor Jonathan Hodgson at UWA. "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."
In the study, 95 Australian participants aged 35 to 75 were recruited 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.
More research is required to better understand how tea may reduce blood pressure, although earlier studies reported a potential link between tea consumption and the improved health of people's blood vessels(2).
"This is a hugely exciting development for us," said Jane Rycroft, senior nutrition and health manager at Unilever's Research & Development laboratories.
"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."
Tea is the second most consumed drink in the world, after water. Unilever is the world's largest tea company, making brands including Lipton and PG Tips. Every year, consumers in more than 130 countries drink 117 billion cups of Unilever tea.
Note: Individuals with high blood pressure should consult their physicians for medical advice and treatment.
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(1)Hodgson, JM, Puddey, IB, Woodman, RJ, et.al. Effects of black tea on blood pressure: a randomized controlled trial. Arch Intern Med. 2012;172(2):186-188.