Drink 3 or More Cups of Tea a Week and You Might Live Longer, Study Suggests
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Tea lovers, it's time to rejoice. A new research study published in the European Journal of Preventive Cardiology suggests that drinking tea at least three times per week is associated with a longer and healthier life.1
Sitting under a tree drinking tea
As legend goes, in 2737 BC, Shen Nung, the Chinese emperor and renowned herbalist, was sitting underneath a Camellia sinesis tree (isn't that how all of the best stories start?!). His servant was boiling a cup of drinking water when leaves from the tree blew into the water. Nung decided to taste test the concoction of water and leaves served up to him. Low and behold, he had drunk the first cup of "tea".
Nowadays tea comes in a variety of different forms and flavors, and is enjoyed by many; it’s the most widely consumed drink next to water.
Why a brew is good for you
The proposed health benefits of drinking tea are an interesting topic that, in the past, "stirred" the scientific community. However, it is increasingly acknowledged that tea contains polyphenols and other metabolites that may decrease the risk of developing diseases such as cancer, cardiovascular disease (CVD) and arthritis.2
A new study by researchers at the Chinese Academy of Medical Sciences aimed to investigate the associations of tea consumption with the risk of atherosclerotic CVD and all-cause mortality.
The study utilized 100,902 participants from the project of Prediction for ASCVD Risk in China (also known as the China-PAR project) that did not have any history of heart attack, cancer or stroke. The participants were divided into two groups: "habitual", defined as drinking tea >3 per week, and "non-habitual" tea drinkers, defined as drinking <3 per week.
The sample of participants were then followed for a median of 7.3 years, in which time a combination of face-to-face questionnaires were used to collect data on tea consumption, demographic characteristics, lifestyle risk factors and personal medical history. Blood specimens were also collected at study visits after fasting for at least 10 hours in order to assess blood glucose and blood lipid levels.
Putting tea to the test
During the follow-up period, 3683 atherosclerotic CVD events occurred, 1477 atherosclerotic CVD deaths were reported and 5479 all-cause deaths were recorded. From this data, the researchers were able to conclude that habitual tea consumers had a 20% lower risk of incident heart disease and stroke, a 22% lower risk of fatal heart disease and stroke, and 15% decreased risk of all-cause death.
The data also implies that 50-year-old habitual tea drinkers were developing coronary heart disease and stroke approximately 1.41 years later than non-habitual tea drinkers and would live approximately 1.26 years longer.
Senior author Dongfeng Gu, Chinese Academy of Medical Sciences, said: "The protective effects of tea were most pronounced among the consistent habitual tea drinking group. Mechanism studies have suggested that the main bioactive compounds in tea, namely polyphenols, are not stored in the body long-term. Thus, frequent tea intake over an extended period may be necessary for the cardioprotective effect."
Impact of changing tea drinking behaviors
The longitudinal nature of the study must account for the fact that certain participants might choose to change their tea drinking behaviors over a period of time. The authors did just that; analyzing a subset of 14,081 participants with assessments at two specific time points. Compared to non-habitual tea drinkers, habitual tea drinkers that maintained their habit in both surveys had demonstrated a 39% lower risk of incident heart disease and stroke, 56% decreased risk of fatal heart disease and stroke and a 29% decreased risk of all-cause death.
Does the type of tea make a difference?
A sub analysis of the results revealed that drinking green tea was linked with approximately 25% lower risk for incident heart disease, stroke, fatal heart disease stroke and all-cause death. For black tea, no significant association was discovered.
Of these findings, Gu says: "In our study population, 49% of habitual tea drinkers consumed green tea most frequently, while only 8% preferred black tea. The small proportion of habitual black tea drinkers might make it more difficult to observe robust associations, but our findings hint at a differential effect between tea types."
The fact that green tea is a rich source of polyphenols is one proposed explanation for the findings. Black tea, unlike green tea, is fully fermented, which oxidizes polyphenols and may lead to the loss of their antioxidant qualities. Furthermore, black tea is often offered with milk, which has been postulated to offset the health effects of tea in terms of vascular function.
Males vs females
Analysis also revealed that the protective effects of habitual tea consumption were more pronounced in males when compared to females. First author of the study, Xinyan Wang, Chinese Academy of Medical Sciences, suggests these differences may be attributed to the amount of tea consumption: "One reason might be that 48% of men were habitual tea consumers compared to just 20% of women. Secondly, women had much lower incidence of, and mortality from, heart disease and stroke. These differences made it more likely to find statistically significant results among men."
She concludes: "The China-PAR project is ongoing, and with more person-years of follow-up among women the associations may become more pronounced."
References:
1. Wang et al. (2020). Tea consumption and the risk of atherosclerotic cardiovascular disease and all-cause mortality: The China-PAR project. European Journal of Preventative Cardiology, 0(00) 1–8. DOI: 10.1177/2047487319894685.
2. Khan, N., & Mukhtar, H. (2013). Tea and health: studies in humans. Current pharmaceutical design, 19(34), 6141–6147. doi:10.2174/1381612811319340008.
