A nice cup of tea for your blood pressure?

24th January  2012 - Many of us look forward to a nice cup of tea, now new research suggests it can help lower blood pressure.

Australian researchers compared a group of people drinking three cups of black tea a day with another group given a similar tasting dummy drink. The black tea drinkers’ systolic (the top number in blood pressure readings) and diastolic (the lower number) blood pressures were found to be  two to three points (mm/Hg) lower.

Small difference, big impact?

A couple of points may not seem like much, but researchers say even small reductions in blood pressure can have a major impact on the prevalence of high blood pressure (hypertension) and a person's risk of heart disease, because so many people world-wide have the condition .

Writing in the Archives of Internal Medicine, the team from the School of Medicine and Pharmacology at the University of Western Australia in Perth say: "At a population level, the observed differences in BP [blood pressure] would be associated with a 10% reduction in the prevalence of hypertension and a 7% to 10% reduction in the risk of [heart disease and stroke]."

The researchers say it’s the first time that long-term use of black tea has been shown to lower blood pressure in people with normal to high-normal blood pressure.

Put the kettle on?

In the study, researchers looked at the effect of black tea on blood pressure levels among 95 men and women who were regular tea drinkers. Their average systolic blood pressure was between 115 and 150 at the start of the study.

Half of the participants drank three cups of black tea per day for six months, and the other half drank a placebo drink with a similar flavour and caffeine content. Both groups were similar in terms of gender, age and weight and were picked randomly.

By the end of the study, those who drank black tea experienced an average reduction of between two and three points in their 24-hour average systolic blood pressure level and about two points in their diastolic level.

Tea science

Researchers say there are some possible explanations for this health benefit.

Studies have shown that drinking black tea can improve the function of the endothelial cells, which line the interior of blood vessels. Endothelial dysfunction is an early indicator of blood pressure changes.

Recent research has also suggested that green tea and its flavonoids-many of which are structurally similar to black tea flavonoids-together with caffeine can reduce body weight and abdominal fat.

Reaction

In an emailed statement, Paul Newman, the Blood Pressure Association chief executive says: "This was a very small study with good intentions. A much larger study would be required though to show any effect if one existed.

"The best way to protect against developing high blood pressure is to keep to a low salt, healthy diet, don't drink too much alcohol, maintain a healthy weight and take regular exercise."

Paul Newman says all adults should know their blood pressure numbers and have their blood pressure checked every year.