Summary: Drinking two or more cups of black tea per day moderately reduces mortality risk, researchers report.
Source: American College of Physicians
A prospective cohort study found that drinking black tea may be associated with a moderately lower mortality risk. The risk was lowest among persons drinking two or more cups of tea per day.
The findings are published in Annals of Internal Medicine.
Tea is one of the most consumed beverages worldwide. Previous research has suggested an association between tea consumptions and lower mortality risk in populations where green tea is the most common type of tea. In contrast, published studies in populations where black tea drinking is more common are limited with inconsistent findings.
Researchers from the National Institutes of Health conducted a study to evaluate the associations of tea consumption with all-cause and cause-specific mortality using data from the U.K. Biobank, where black tea drinking is common.
They also assessed whether the associations differ by use of common tea additives (milk and sugar), tea temperature, and genetic variants affecting the rate at which people metabolize caffeine.
The U.K. Biobank includes data on a half a million men and women, aged 40 to 69 years, who completed a baseline questionnaire between 2006 and 2010. Of those, 85 percent reported regularly drinking tea and of them, 89 percent reported drinking black tea.
Relative to tea nondrinkers, participants who reported drinking 2 or more cups each day had 9 to 13 percent lower risk for mortality.
The associations were observed regardless of whether participants also drank coffee, added milk or sugar to their tea, their preferred tea temperature, or genetic variants related to caffeine metabolism.
According to the authors, their findings suggest that tea, even at higher levels of intake, can be part of a healthy diet.
498 043 men and women aged 40 to 69 years who completed the baseline touchscreen questionnaire from 2006 to 2010.
Self-reported tea intake and mortality from all causes and leading causes of death, including cancer, all cardiovascular disease (CVD), ischemic heart disease, stroke, and respiratory disease.
During a median follow-up of 11.2 years, higher tea intake was modestly associated with lower all-cause mortality risk among those who drank 2 or more cups per day. Relative to no tea drinking, the hazard ratios (95% CIs) for participants drinking 1 or fewer, 2 to 3, 4 to 5, 6 to 7, 8 to 9, and 10 or more cups per day were 0.95 (95% CI, 0.91 to 1.00), 0.87 (CI, 0.84 to 0.91), 0.88 (CI, 0.84 to 0.91), 0.88 (CI, 0.84 to 0.92), 0.91 (CI, 0.86 to 0.97), and 0.89 (CI, 0.84 to 0.95), respectively. Inverse associations were seen for mortality from all CVD, ischemic heart disease, and stroke. Findings were similar regardless of whether participants also drank coffee or not or of genetic score for caffeine metabolism.
Potentially important aspects of tea intake (for example, portion size and tea strength) were not assessed.
Higher tea intake was associated with lower mortality risk among those drinking 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.
Primary Funding Source:
National Cancer Institute Intramural Research Program.