A research team from Glasgow University have spent the past 37 years tracking the health of more than 6,000 men. They found that men who indulged in over 7 cups of tea a day increased their chances of developing prostate cancer by 50% compared to moderate tea drinkers, or those who avoid Britain’s favourite drink entirely.
However, the team were uncertain whether tea was a cause of the cancer, or if it helped drinkers live to an age where they were more likely to develop the disease.
In Scotland, prostate cancer is the most common to develop in men, and has seen a rise of 7.4% in diagnosed cases during the 2000s.
The study, called the Midspan Collaborative Study, began in 1970. It collected data from 6,016 men aged between 21 and 75 who were living in Scotland.
They were asked to fill in a questionnaire that asked for their usual consumption of tea, coffee, alcohol, tobacco, general fitness, and were asked to attend a medical examination.
Roughly a quarter of the men polled reported themselves to be heavy tea drinkers. Out of these, 6.4% developed prostate cancer during the following 37 years.
Researchers found this was significantly higher than the remaining three quarters, who drank four cups a day or less.
Leading the study was Dr Kashif Shafique of Glasgow University’s Institute for Health and Wellbeing.
He said: "Most previous research has shown either no relationship with prostate cancer for black tea or some preventive effect of green tea.
"We don't know whether tea itself is a risk factor or if tea drinkers are generally healthier and live to an older age when prostate cancer is more common anyway."
"We found that heavy tea drinkers were more likely not to be overweight, be non alcohol-drinkers and have healthy cholesterol levels.
"However, we did adjust for these differences in our analysis and still found that men who drank the most tea were at greater risk of prostate cancer."
Dr Kate Holmes, head of research at the Prostate Cancer Charity, said: "Whilst it does appear that - of the 6,000 men who took part in this study - those who drank seven or more cups of tea each day had an increased risk of developing prostate cancer, this did not take into consideration family history or any other dietary elements other than tea, coffee and alcohol intake.
"We would therefore not wish any man to be concerned that drinking a moderate amount of tea as part of a healthy diet will put them at an increased risk of developing prostate cancer."