Black Tea Reduces Stroke and Heart Disease Risk by Up To 50 Percent
Green tea is often lauded for the many amazing health benefits that it touts. However, black tea drinkers should rejoice after a a team of Australian scientists found that its daily consumption could help to reduce the risk of heart disease in the general population by reducing blood pressure.
While green tea usually loses its flavor within a year, black tea retains its stronger flavour for several years. Black tea undergoes full oxidation and fermentation.
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 which may have a substantial long-term benefit.
A previous study of over 3,000 adults in Saudi Arabia - where black tea is favored over green - found that regular consumption of the dark brew can reduce the risk of coronary heart disease by fifty percent.
Another long-term study by the Netherlands National Institute of Public Health and the Environment found a correlation between regular consumption of black tea and reduced risk of stroke. Researchers looked at data from a study examining the health benefits of foods that are high in flavonoids - phytonutrients with antioxidant benefits. While some of the flavonoids were obtained from fruits and vegetables, seventy percent came from black tea. The study looked at 552 men over a 15 year period. Researchers concluded that the flavonoids in black tea helped reduce the production of LDL - the "bad" cholesterol that can lead to stroke and heart attacks. Furthermore, men who drank over four cups of black tea per day had a significantly lower risk of stroke than men who drank only two to three cups per day.
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Like green tea, extracts from black tea may also help reduce weight gain and cut body fat levels. Supplementing the diet of lab animals fed a high-fat diet with black tea extracts suppressed body weight gain and body fat levels, with the benefits linked to reduced fat absorption, according to findings published in Nutrition.
Studies funded by the Tea Trade Health Research Association found several doses of black tea every day not only reduced plaque build-up but also helped control bacteria while essentially preventing cavities.
The research team who published the recent study in JAMA, 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 2-3 mm Hg compared to non-tea drinkers.
A separate study by Dr. Joseph Vita at Boston's School of Medicine supported these results. For four months, sixty-six men drank four cups of either black tea or a placebo daily. Dr. Vita concluded that drinking black tea can help reverse an abnormal functioning of the blood vessels that can contribute to stroke or heart attack. Furthermore, improvement in the functioning of the blood vessels was visible within two hours of drinking just one cup of black tea.
"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.