Regular tea intake tied to reduced ASCVD risk
Regular tea consumption may be linked to reduced incidence and mortality from atherosclerotic cardiovascular disease (ASCVD), according to a study from China.
“Habitual tea consumption is associated with lower risks of [CVD] and all-cause death,” said study first author Dr Xinyan Wang from the Chinese Academy of Medical Sciences and Peking Union Medical College in Beijing, China. “The favourable health effects are the most robust for green tea and for long-term habitual tea drinkers.”
Participants were 100,902 individuals enrolled in the prospective China-PAR* study. Information on tea consumption was obtained from questionnaires, while interviews, hospital records, and death certificates provided information on outcomes. The participants were followed up for a median 7.3 years during which time there were 3,683 incidents of ASCVD**, 1,477 deaths due to ASCVD, and 5,479 all-cause deaths.
At baseline, 31.6 percent of participants were characterized as habitual tea drinkers (≥3 times/week), of whom 49 percent most commonly consumed green tea.
Compared with never or non-habitual tea drinkers (<3 times/week), habitual tea drinkers had lower risks of ASCVD (adjusted hazard ratio [adjHR], 0.80, 95 percent confidence interval [CI], 0.75–0.87), CHD (adjHR, 0.82, 95 percent CI, 0.70–0.96), and stroke (adjHR, 0.80, 95 percent CI, 0.73–0.87). [Eur J Prev Cardiol 2020;doi;10.1177/2047487319894685]
Habitual tea drinkers also had lower risks of mortality due to ASCVD (adjHR, 0.78, 95 percent CI, 0.69–0.88) or stroke (adjHR, 0.73, 95 percent CI, 0.63–0.86), and all-cause mortality (adjHR, 0.85, 95 percent CI, 0.79–0.90).
Habitual tea drinkers also experienced a delay in developing ASCVD, CHD, and stroke, by 1.41, 0.32, and 1.23 years, respectively. At age 50 years, they had 1.26 years greater life expectancy than never or non-habitual tea drinkers.
Of the 14,081 participants with information on changes in tea consumption habits, the risks of ASCVD, ASCVD mortality, and all-cause mortality were further reduced in those who maintained their tea consumption habits compared with consistent never or non-habitual tea drinkers (adjHR, 0.61, 0.44, and 0.71, respectively). However, among those who began or stopped drinking tea over the follow-up period, no significant association was detected between tea drinking and any of the outcomes.
“The protective effects of tea were most pronounced among the consistent habitual tea drinking group,” noted senior author Dr Dongfeng Gu from the same institution. “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.”
The reduction in CV risk (except CHD mortality) appeared restricted to habitual consumption of green and not black tea, though the researchers recommended caution when interpreting this finding.
“The small proportion of habitual black tea drinkers [8 percent] might make it more difficult to observe robust associations, but our findings hint at a differential effect between tea types,” noted Gu.
The more robust findings in men compared with women may be due to variability in tea drinking habits (48 percent vs 20 percent were habitual tea drinkers) or lower ASCVD incidence and mortality in women, results that may be clarified in ongoing research in this population.
Confirmation of the results through clinical trials could lead to the development of dietary guidelines and recommendations on tea consumption, said the researchers. The findings may also currently be limited to populations with similar tea drinking cultures, they said.