8 September 2009
MedWire News: A study from Japan supports previous evidence that drinking
green tea may have cardiovascular benefits.
The prospective cohort study of elderly people from Shizuoka found regular
green-tea drinkers have significantly lower all-cause and cardiovascular
mortality than those who rarely drink the beverage.
Etsuji Suzuki (Okayama University) and colleagues followed 12,251 individuals
for up to 6 years, from December 1999 to March 2006. All participants completed
a questionnaire at baseline that included items about frequency of green tea
consumption.
The team reports in the Annals of Epidemiology that the proportions of
individuals drinking less than one, one to three, four to six, and seven or more
cups of green tea per day were 2.8%, 25.2%, 48.1%, and 23.9%, respectively.
A total of 1224 participants died over 64,002 person-years of follow-up. An
inverse association was observed between green tea consumption and all-cause and
cardiovascular mortality, but not cancer mortality.
All-cause mortality was 62.0 per 1000 person-years among those consuming less
than one cup of green tea per day compared with 14.4 per 1000 person-years among
those drinking more than seven cups a day.
Corresponding cardiovascular death rates were 17.1 versus 51.0 deaths per 1000
person-years.
Multivariate analysis, adjusting for smoking status, alcohol consumption, body
mass index, and the frequency of physical activity, showed that drinking seven
or more cups of green tea a day was associated with a 26% lower relative risk
for all-cause mortality in the first 3 years of follow-up and 44% lower risk in
the second 3-year period, compared with consuming less than one cup a day.
For cardiovascular mortality, there was a 48% reduction in relative risk
associated with drinking seven or more versus less than one cup of green tea per
day in the first 3 years, and a 62% reduction in the second 3 years of
follow-up.
Over the entire study period there was a 76% reduction in relative risk for
cardiovascular mortality associated with the highest versus lowest level of
green tea consumption among all participants, with 70% and 82% risk reductions
for men and women, respectively.
The authors note that the magnitude of the risk reductions for cardiovascular
mortality are larger than those seen in previous studies in Japan.
“In conclusion, the present study provides more evidence of the protective
effects of green tea on all-cause and cardiovascular disease mortality,” the
team writes.
“The protective effects could have significant implications for public health.”
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Medicine Group Ltd; 2009