Scientists calculate that regular tea drinkers gain 1.41 years of cardiovascular disease-free years and 1.26 years longer of life expectancy at the index age of 50 years.
“The current study indicates that tea might be a healthy beverage for primary prevention against atherosclerotic cardiovascular disease (ASCVD) and premature death,” the paper states.
“Our findings give a further insight into the beneficial role of tea consumption and have great public health implications for guiding primary prevention among general Chinese adults.”
The study’s findings were met with broad agreement by nutrition experts, who point to the tea’s rich source of flavonoids including mainly epicatechin, catechin, and epigallocatechin-3-gallate (EGCG).
Mechanism studies reveal these bioactive compounds to play an important role in lessening oxidative stress, relieving inflammation and enhancing blood vessel cell and cardiac muscle function.
“The study does build on a growing body of evidence that tea contains many healthful properties (such as flavonoids) and builds on the several previous studies which collectively did not find a unanimous conclusion,” says Dr Jenna Macciochi, lecturer in immunology at the University of Sussex.
Liver damage link?
Dr Duane Mellor, registered dietitian and senior teaching fellow at Aston Medical School, Aston University adds “Green tea has been linked with a number of health benefits and this was the case in this study and the journal’s editorial links the associated benefits of green tea to compounds called catechins.”
“However, what should be remembered is that although green tea is safe and may have benefits, the use of green tea supplements should be considered carefully as there has been a number of cases of liver damaged reported in individuals who have consumed these in large doses.”
Colleagues from the Chinese Academy of Medical Sciences and Nanjing Medical University in China began sifting through data collected from 100,902 Chinese adults living in 15 provinces since 1998.
Information on tea consumption was collected through standardised questionnaires. Outcomes were identified by interviewing study participants and checking hospital records and/or death certificates.
During a median follow-up of 7.3 years, 3683 atherosclerotic cardiovascular disease events, 1477 atherosclerotic cardiovascular disease deaths, and 5479 all-cause deaths were recorded.
Habitual tea drinkers had 1.41 years longer of atherosclerotic cardiovascular disease-free years and 1.26 years longer of life expectancy at the index age of 50 years.
The observed inverse associations were strengthened among participants who kept the habit during the follow-up period.
No causal link found
“Speaking more colloquially, habitual tea drinkers might develop ASCVD 1.41 years later or die 1.26 years later than those who never or seldom drank tea,” the team says.
“The observed inverse associations were strengthened among participants who stuck to their habit all along.”
“It’s important to note this study hasn’t found a causal link, and there are confounders and limitations with this type of study – so ‘tea drinkers live longer’ cannot be assumed to mean ‘drinking tea leads to living longer,’” adds Dr Macciochi.
“These studies are inherently subject to confounding e.g. it doesn’t take into account other lifestyle factors. A body of evidence in nutrition suggests that whole diet patterns are more informative of diet-disease relationships than any isolated food or nutrient.”
Polyphenols not responsible
Also commenting on the study’s findings is Gunter Kuhnle, professor of Nutrition and Food Science, at the University of Reading, who points out it is currently not known how tea – or compounds found in tea – affect health.
“The antioxidant effect of polyphenols found in tea has long been assumed to be responsible, but this has been resoundingly disproved in the last decade.
“Some of the compounds found in tea might have a beneficial effect, but this is currently still under investigation,” he adds.
“Among the habitual tea drinkers, only about 10% consumed black tea whereas almost 50% consumed green tea – which is different from the UK population.
“A beneficial effect was only observed for green and other types of tea, but not black tea: however, this might be due to the very small number of black tea drinkers.
“While black and green tea contain similar amounts of caffeine, they differ in their content and composition of polyphenols. However, the data available do not allow us to attribute any observed effect to these differences.”
Source: European Journal of Preventive Cardiology
Published online: DOI: 10.1177/2047487319894685
“Tea consumption and the risk of atherosclerotic cardiovascular disease and all-cause mortality: The China-PAR project.”
Authors: Xinyan Wang et al