The study, published Monday in the journal Annals of Internal Medicine, found that tea drinkers have a "slightly" lower risk of death from all causes, as well as death from cardiovascular disease, coronary heart disease and stroke.
Although there has been evidence in the past for a link between tea consumption and life expectancy, these studies mostly evaluated green tea and were conducted in typical Asian populations. Research on black tea, the most commonly consumed tea in the United Kingdom, has been limited to date and has had mixed results.
However, the current study suggests that the health benefits of black tea are similar to those of green tea and that higher tea consumption is part of a healthy diet.
Two cups of tea a day are associated with a lower risk of death.
In this study, scientists from the National Cancer Institute evaluated health data on 498,043 people between the ages of 40 and 69 in the United Kingdom from UK Biobank, a large biomedical database.
Participants filled out a basic questionnaire with questions about tea drinking habits and lifestyle, and researchers compared these self-reported habits with all-cause mortality.
Participants were followed for about 11 years, and the researchers found that those who drank at least two cups of tea a day had a 9-13% lower risk of all-cause mortality compared to those who did not drink at all.
They also found that those who drank more tea had lower rates of death from cardiovascular disease, coronary heart disease and stroke.
This was true regardless of how the tea was drunk (hot or cold, with or without milk or sugar) or how quickly or slowly caffeine was metabolized.
The health benefits show up after about two cups of tea a day. Drinking more than that will not do any harm, but it will not be good for your health either.
Health Benefits of Green Tea
The health benefits associated with black tea
Dana Hannes, PhD, MPH, RD, senior clinical dietitian at UCLA Medical Center and assistant professor at the UCLA School of Public Health, said black tea contains high levels of polyphenols and flavonoids known to reduce oxidative stress and inflammation, but this new study was not conducted.
"What this study looked at may be related to the action of these phytonutrients and compounds in tea, which reduce oxidative stress and inflammation, thereby reducing the risk of all-cause mortality," Hannes, who is also the author of The Survival Prescription, told Health.
Both inflammation and oxidative stress damage our cells and can eventually lead to cancer, according to Benjamin Hirsch, MD, director of preventive cardiology at Northwell Health Sandra Atlas Bath Heart Hospital, who was not involved in the new study.
Hannes added that inflammation is also a factor in many other diseases, such as heart disease, stroke and diabetes.
Inflammation depends largely on what we eat, drink and other things.
But by consuming foods and drinks rich in phytonutrients - compounds produced by plants - people can boost their immunity and increase their nutritional value by repairing and protecting damaged cells.
As with fruits and vegetables, polyphenols and flavonoids help reduce inflammation and protect cells from damage, says Dr. Hirsch.
According to Guy L. Mintz, M.D., director of cardiovascular health and lipidology at Northwell Health's Sandra Atlas Bath Heart Hospital, consuming flavonoids and, in particular, polyphenols, phytonutrients found in black tea, can improve vascular function, lower bad cholesterol, among other things. and managing insulin sensitivity, new research has not been conducted.
Tea consumption may not be the only factor.
Although the researchers concluded that tea is part of a healthy diet, even in large quantities, it is important to note that the participants in this study were predominantly white, so further research is needed to determine how tea consumption affects other populations.
"Although the associations have been comprehensively and thoroughly evaluated, these results should be replicated in future studies and extended to other diverse populations," said Maki Inoue-cho, PhD, a staff scientist at the National Cancer Institute and the Division of Cancer Epidemiology and Genetics, author of the relevant study, at a media briefing.Hannes said further research is needed on how lifestyle and genetic factors influence the benefits of drinking tea, especially since the study is observational in nature.
'Does it mean they drink tea instead of sugar-sweetened beverages. Tea is a great drink containing phytonutrients, polyphenols and flavonoids. Is it a combination of all of the above." says Hannes, adding that the answer is not yet known.
The findings suggest that tea can be part of a healthy diet, but that doesn't mean everyone should drink several cups of tea a day, the researchers said.
If you do include tea in your diet, listen to your body. Tea contains a lot of caffeine, which some people may be sensitive to. It also has diuretic properties, and drinking too much can lead to dehydration, Dr. Mintz says.
However, those who like to drink two to three cups of tea a day can continue to drink it because of the potential health benefits. If you don't have a caffeine problem, drink it to your health," says Hannes, "but you won't get more than a couple of cups a day.
