Health benefits tea drinkers enjoy

Tea can be part of a healthy diet. [iStockphoto]

The study, published Monday in Annals of Internal Medicine, found the association held up for heart disease deaths, but there was no clear trend for cancer deaths. Researchers weren't sure why, but it's possible there weren't enough cancer deaths for any effect to show up, said Maki Inoue-Choi, who led the study.

A study like this, based on observing people's habits and health, can't prove cause and effect.

"Observational studies like this always raise the question: Is there something else about tea drinkers that makes them healthier?" said Marion Nestle, a professor of food studies at New York University. "I like tea. It's great to drink. But a cautious interpretation seems like a good idea."

There's not enough evidence to advise changing tea habits, said Inoue-Choi.

"If you drink one cup a day already, I think that is good," she said. "And please enjoy your cup of tea."