Tea drinkers
live longer
Sophia Antipolis
Drinking tea at least three times a
week is linked with a longer and healthier life, according to a study published
today in the European Journal of Preventive Cardiology, a
journal of the European Society of Cardiology (ESC).
“Habitual tea consumption is
associated with lower risks of cardiovascular disease and all-cause death,”
said first author Dr. Xinyan Wang, Chinese Academy of Medical Sciences,
Beijing, China.
“The favourable health effects are the most robust for green tea and for long-term habitual tea drinkers.”
“The favourable health effects are the most robust for green tea and for long-term habitual tea drinkers.”
The analysis included 100,902
participants of the China-PAR project with no history of heart
attack, stroke, or cancer. Participants were classified into two groups:
habitual tea drinkers (three or more times a week) and never or non-habitual
tea drinkers (less than three times a week) and followed-up for a median of 7.3
years.
Habitual tea consumption was
associated with more healthy years of life and longer life expectancy.
For example, the analyses estimated that 50-year-old habitual tea drinkers would develop coronary heart disease and stroke 1.41 years later and live 1.26 years longer than those who never or seldom drank tea.
Compared with never or non-habitual
tea drinkers, habitual tea consumers had a 20% lower risk of incident heart
disease and stroke, 22% lower risk of fatal heart disease and stroke, and 15%
decreased risk of all-cause death.
The potential influence of changes
in tea drinking behaviour were analysed in a subset of 14,081 participants with
assessments at two time points. The average duration between the two surveys
was 8.2 years, and the median follow-up after the second survey was 5.3 years.
Habitual tea drinkers who maintained
their habit in both surveys had a 39% lower risk of incident heart disease and
stroke, 56% lower risk of fatal heart disease and stroke, and 29% decreased
risk of all-cause death compared to consistent never or non-habitual tea
drinkers.
Senior author Dr. 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.”
In a subanalysis by type of tea,
drinking green tea was linked with approximately 25% lower risks for incident
heart disease and stroke, fatal heart disease and stroke, and all-cause death.
However, no significant associations were observed for black tea.
Dr. Gu noted that a preference for
green tea is unique to East Asia. “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.”
Two factors may be at play. First,
green tea is a rich source of polyphenols which protect against cardiovascular
disease and its risk factors including high blood pressure and dyslipidaemia.
Black tea is fully fermented and during this process polyphenols are oxidised into pigments and may lose their antioxidant effects. Second, black tea is often served with milk, which previous research has shown may counteract the favourable health effects of tea on vascular function.
Black tea is fully fermented and during this process polyphenols are oxidised into pigments and may lose their antioxidant effects. Second, black tea is often served with milk, which previous research has shown may counteract the favourable health effects of tea on vascular function.
Gender-specific analyses showed that
the protective effects of habitual tea consumption were pronounced and robust
across different outcomes for men, but only modest for women. Dr. Wang said:
“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 added: “The China-PAR project is
ongoing, and with more person-years of follow-up among women the associations
may become more pronounced.”
The authors concluded that
randomised trials are warranted to confirm the findings and provide evidence
for dietary guidelines and lifestyle recommendations.
