A warm cup of tea in your favorite mug can seem to heal the soul -- and a new study finds it may be good for your body, too.
Drinking two or more cups of black tea a day is associated with lower risk of death from all causes, according to the study published Monday in Annals of Internal Medicine.
The study looked at nearly 500,000 men and women ages 40 to 69 years old who participated in the UK Biobank, which houses in-depth genetic and health information, between 2006 and 2010. The database included information participants reported about their own tea drinking habits, such as frequency and what they added to their cup, according to the study.
Some participants didn't drink black tea at all, but since the data came from the United Kingdom, there also were plenty of people who drank it regularly -- and some who drank up to 10 cups a day, said lead study author Maki Inoue-Choi, an epidemiologist at the National Cancer Institute in the US.
The Biobank followed up about 10 years after the original survey, and researchers found that people who drank two or more cups of tea daily in the interim were less likely to have died from causes such as cardiovascular disease, ischemic heart disease and stroke, according to the study.
The research is an exciting look into tea drinking habits, but there is still more work that needs to be done before recommending dietary changes, said Howard Sesso, an associate professor of medicine at Harvard Medical School and associate epidemiologist at Brigham and Women's Hospital in Boston. Sesso was not involved in the study.
"The authors tried to control for other dietary factors, but tea drinkers typically differ from non-tea drinkers in other ways that would likely weaken these findings. We really need more randomized clinical trials testing tea intake," Sesso said in an email.
What about the milk and sugar?
For many tea drinkers, the process of making their tea is crucial.
What temperature does the water need to be? Do you take it black? Do you add milk? Sugar? How much?
If you can't imagine taking your tea black, don't worry just yet. There was no significant reduction in health benefits for those who added milk or sugar, according to the study.
That doesn't necessarily mean it's the healthiest way to drink tea, though. Inoue-Choi said health experts strongly encourage limiting sugar and the saturated fats like those in milk.
Should you change your drinking habits?
Although it's hard to say for sure from the research so far, Inoue-Choi said there are some good reasons why black tea might be so beneficial.
"There are multiple possible mechanisms," she said. "Tea is rich in bioactive compounds ... They have the potential to decrease oxidated stress and inflammation. That could protect against health conditions such as cancer and heart disease."
There has been plenty of research on the health benefits of green tea.
Observational studies, like one from 2013, suggest that it could slow the growth of precancerous legions, while a 2014 study found that green tea consumption is associated with a lower risk of cognitive decline.
Both black and green tea come from variations of the same plant, camellia sinensis, but little research before now has looked into the impacts of drinking black tea, Inoue-Choi said.
Because of the lack of research, it may not be time to add black tea into your daily routine just yet, she added.
"Our findings may provide reassurance to people who already drink tea every day, but we don't recommend making decisions about whether people start drinking tea or change how much they are drinking right now," Inoue-Choi said.
People shouldn't rely on the results from a single study for these kinds of changes, she said, and more research is needed to round out the findings.
"This study does not prove that tea intake reduces mortality, but it does suggest that if you are currently drinking tea -- and especially black tea, which was the tea type of choice in the UK -- you can continue to do so," Sesso said.