Green Tea Slashes Heart Disease and Cancer Death Risk
Lee Swanson Research Update
Seven cups of green tea a day over the long-term may massively reduce the risk of death from heart disease and colorectal cancer, a new study from Japan suggests.
Compared to people who drank less than one cup a day, seven or more cups of green tea a day may reduce the risk of dying from heart disease by a whopping 75%, report scientists from Okayama University in the Annals of Epidemiology.
Additionally, a reduction in the risk of colorectal cancer mortality of 31% was observed for people who drank more than seven cups of green tea a day, compared to people who drank less than three cups a day.
"To our knowledge, this is the first cohort study that shows the inverse association between green tea and colorectal cancer mortality," wrote the researchers, led by Etsuji Suzuki.
The strong effects observed in the study may be due to long-term, high consumption of green tea, said the researchers. Only people aged between 65 and 84 participated in the study.
"Assuming that green tea consumption at the time of assessment is sufficiently representative of long-term, previous exposure to make a plausible link with the risk of mortality, the longer cumulative exposure to green tea may be responsible for the stronger effects of the present study, [compared to past studies]," they added.
Green tea contains between 30% and 40% of water-extractable polyphenols, while black tea (green tea that has been oxidized by fermentation) contains between 3% and 10%. The four primary polyphenols found in fresh tea leaves are epigallocatechin gallate (EGCG), epigallocatechin (EGC) epicatechin gallate (ECG) and epicatechin (EC).
The Japanese team recruited 14,001 elderly residents in Japan, of which 12,251 individuals were analyzed to estimate the various associations between green tea consumption and all-cause mortality, cardiovascular disease (CVD) and cancer.
During an average of 5.2 years of follow-up, 1,224 participants died, 400 were due to cancer and 405 from CVD.
Compared to people who drank less than one cup per day, drinking seven or more cups of green tea a day was associated with a 55% and 75% lower risk of all-cause and CVD mortality, respectively, said the researchers. Furthermore, "green tea consumption was associated with lower risk of colorectal cancer mortality," they said.
Annals of Epidemiology 19(10):732-739, 2009