Drinking tea may improve cardiovascular health

The benefits of drinking tea may extend to improving cardiovascular health. After adjusting for multiple variables, adults who drank at least one cup of tea per day had a slower progression of coronary artery calcium and 29 percent lower incidence of cardiovascular events compared with adults who never drank tea.

The same study found that there was no association between drinking at least one cup of coffee per day and the progression of coronary artery calcium or cardiovascular events. However, participants who drank less than one cup of coffee per day had an increased incidence of cardiovascular events compared with those who never drank coffee.

Lead researcher P. Elliott Miller, MD, of the National Institutes of Health and Johns Hopkins University in Baltimore, and colleagues published their results online in The American Journal of Medicine Sept. 15.

“Our study supports regular tea consumption as part of a heart healthy diet as recommended by the American Heart Association (AHA),” the researchers wrote. “Further studies are needed to delineate whether the protective association with tea consumption can be harnessed or if tea drinkers generally have healthier behaviors not measured in this study.”

The researchers evaluated 6,508 participants from the Multi-Ethnic Study of Atherosclerosis, a prospective study of adults between 44 and 84 years old from Columbia University, Johns Hopkins University, Northwestern University, University of California-Los Angeles, University of Minnesota and Wake Forest University. They excluded participants who had a history of cardiovascular disease at baseline.

The mean age of the participants was 62.3 years old, and 52.9 percent were women. Of the participants, 25 percent never drank coffee, 24 percent drank less than a cup of coffee per day and 50.9 percent drank at least one cup of coffee per day. In addition, 57.6 percent of participants said they never drank tea, 29.5 percent drank less than one cup per day and 12.9 percent drank at least one cup per day.

Further, 49.9 percent of participants had a coronary artery calcium score of 0, 26.5 percent had a score from 1 to 99 and 23.6 percent had a score of 100 or greater.

After a median follow-up of 11.1 years, the incidence of cardiovascular events was 10.8 per 1,000 person-years and the incidence of hard cardiovascular events was 7.5 per 1,000 person-years. Cardiovascular events included MI, angina resulting in revascularization, resuscitated cardiac arrest, stroke and cardiovascular death, while hard cardiovascular events included cardiovascular events except for angina resulting in revascularization.

A multivariable model found that participants who drank at least one cup of tea per day had a lower prevalence of coronary artery calcium scores of 100 or greater compared with those who did not drink tea. In addition, longitudinal analyses found that participants who drank at least one cup of tea per day had a reduced progression of coronary artery calcium.

Further, drinking less than one cup of coffee per day was associated with an increased incidence of cardiovascular events compared with not drinking coffee, while drinking at least one cup of tea per day was associated with a lower incidence of cardiovascular events compared with not drinking tea. The researchers also mentioned that caffeine intake was not associated with cardiovascular events.

They added that the study had a few limitations, including that they used a retrospective questionnaire to evaluate coffee and tea intake. The questionnaire did not differentiate between decaffeinated or caffeinated beverages or between green and black tea, although it did ask about caffeine consumption. They suggested that future studies track participants’ diet through smartphone fitness applications or other means.