WAlthough green tea has long been known for its health benefits and reputation, the research is mixed about black tea. One problem, says Maki Inoue-Choi, an epidemiologist at the National Cancer Institute, is that large observational studies on tea and mortality have focused on countries like Japan or China—places where green tea is more popular.
InoueChoi, along with her coworkers, analyzed data from the United Kingdom where black tea is popular to fill that gap. These results were published by the journal on Aug. 29 after Inoue-Choi and her colleagues surveyed approximately 500,000 people. They followed them for an average of 11 years. Annals of Internal MedicineThis gave black tea an extra boost. Among the population of tea drinkers—89% of whom drank black tea, compared to 7% who drank green—drinking tea was associated with a modestly lower mortality risk for those who had two or more cups a day compared to non-drinkers. People who added milk or sugar also experienced the benefit, and the results remained consistent regardless of the tea’s temperature. The findings also indicate that tea drinkers had a lower risk of dying from cardiovascular disease, ischemic heart disease, and stroke than those who didn’t drink tea.
While it’s difficult to say why people who drink tea may live longer, it’s not entirely a surprise. According to Inoue-Choi, tea is “very rich in bioactive compounds” that reduce stress and inflammation, including polyphenols and flavonoids.
A 2020 study that used the same British database as the new research found that there’s an association between higher consumption of both black and green tea and biomarkers that predict cardiometabolic health, including lower cholesterol levels. Studies have also shown that tea may lower blood pressure.
Going forward, researchers should take a closer look at the connection between tea and cardiovascular disease, says Rob M. van Dam, professor of exercise and nutrition sciences at George Washington University’s Milken Institute School of Public Health, who did not participate in the study. One striking thing about the new research, he notes, is that there isn’t an association between increasing the dose of tea—the amount a person consumes—and decreased mortality after the person had consumed two or three cups. He said that the exception is when you remove coffee drinkers. They may have been able to make it more difficult to find a link between increased tea intake and higher mortality. It was clearer without the caffeine drinkers that tea consumption is associated with lower mortality from heart disease. “The association between tea consumption and cardiovascular mortality may be driving the association between tea consumption and all-cause mortality,” van Dam says.
This is not to suggest that you shouldn’t run for your life. The new research is based on an observational study—meaning that the evidence wasn’t gathered from an experiment, and the results were inferred by the researchers. The findings shouldn’t be used to make health decisions, and must be replicated in randomized clinical trials, experts say. Plus, the magnitude of the association between tea drinking and mortality was modest, which means it’s likely that another characteristic of people who drink tea could have led to this effect, says van Dam. People who drink tea could hypothetically be less inclined to consume soft drinks.
According to InoueChoi, these new results should be comforting for tea drinkers. But “people shouldn’t change how many cups of tea to drink every day because of these results,” she says.
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