Drinking green tea can substantially cut the risk of dying from a range of illnesses, a Japanese study has found.
Green tea is a favourite drink in Japan
The research, which looked at over 40,000 people, found the risk of fatal cardiovascular disease was cut by more than a quarter.
But British heart experts said the benefits may be linked to the whole Japanese diet, which is healthier than that eaten in the west.
The work is published in the Journal of the American Medical Association.
Tea is the most consumed beverage in the world, aside from water.
Three billion kilograms of tea are produced each year worldwide.
Studies carried out in laboratories and on animals have suggested green tea in particular has extensive health benefits.
Women 'greater benefit'
In this study, which began in 1994, researchers from Tohoku University looked at how humans could benefit.
They examined data on 40,530 healthy adults aged 40 to 79 in north-eastern Japan, where green tea is widely consumed.
Around 80% of people in the region drink green tea, with more than half consuming three or more cups each day.
The people in the study were followed for up to 11 years (1995-2005), when 4,209 people died from all causes.
The researchers also looked at seven years' worth of data (from 1995-2001) to look at deaths from specific causes.
In that period, 892 people died of cardiovascular disease (CVD) and 1,134 participants died of cancer.
Compared with people who drank less than one cup per day of green tea, those who consumed five or more had a 16% lower risk of dying from any cause during the 11-year study.
They also had a 26% lower risk of dying from CVD in the seven years of follow-up.
There was no significant association between green tea consumption and death from cancer.
Throughout the study, the benefits of green tea appeared greater in women.
Those who drank five cups or more of green tea each day had a 31% lower risk of dying from cardiovascular disease compared with those who had less than one.
But the study failed to find a beneficial link between drinking black or oolong tea and a reduced risk of dying from CVD.
'Low disease rate'
Dr Shinichi Kuriyama, who led the research, said: "The most important finding is that green tea may prolong people's lives through reducing the risk of cardiovascular disease."
The study attempted to take account of other factors, such as diet.
But Ellen Mason, a cardiac nurse at the British Heart Foundation, said the Japanese diet as a whole was particularly healthy, and the findings may not apply to people eating western diets.
"The rate of heart disease in Japan is already one of the lowest in the world, and the Japanese diet is believed to play a substantial role in keeping this low.
"Drinking 3-4 cups of green tea in parts of Japan is a daily habit.
"The average British diet contains more saturated fat than the average Japanese diet, and our levels of heart disease are relatively high compared with many other countries in the world.
"It is questionable whether drinking the same amount of green tea a day in the UK would have a significant impact on levels of heart disease."
She added: "Clinical trials are now needed to discover whether something as simple as green tea really can prevent deaths from heart disease."