A prospective study of half a million tea drinkers in the UK aged 40-69 has shown that higher tea intake was “modestly associated with lower all-cause mortality risk among those who drank 2 or more cups per day,” regardless of genetic variation in caffeine metabolism. These findings suggest that tea, even at higher levels of intake, can be part of a healthy diet, the study concluded.

Led by researchers at the National Cancer Institute, part of the National Institutes of Health, results from this large and comprehensive analysis were published in the Annals of Internal Medicine.

Past studies finding a modest association between higher tea intake and lower risk of death have mainly focused on Asian populations, who commonly drink green tea. Studies on black tea have yielded mixed results.

In the new study, the researchers found that people who consumed two or more cups of tea per day had a 9-13% lower risk of death from any cause than people who did not drink tea. Higher tea consumption was also associated with a lower risk of death from cardiovascular disease, ischemic heart disease, and stroke. The association was seen regardless of preferred tea temperature, the addition of milk or sugar, and genetic variations affecting the rate at which people metabolize caffeine.

The study involved 498,043 men and women between ages 40 and 69 who participated in a large cohort study called UK Biobank. The participants were followed for about 11 years, and death information came from a linked database from the UK National Health Service.