The Ohsaki Study
The Ohsaki Study
The green tea studies have being performed in oriental countries where the consumption is large and widespread.
The objective of this studywas to investigate the associations between green tea consumption and all-cause and cause-specific mortality for cardiovascular and cancer disease in Japan.
The observation was carried out on a wide number of subjects: it was initiated in 1994 as population-based, prospective cohort study among 40,530 Japanese adults, from 40 to 79 years hold who had not clinical history of stroke, coronary hearth desease, or cancer at baseline. The participants were followed up for up 11 years (1995-2005) for all-cause mortality and for up 7 years (1995-2001) for cardiovascular disease and cancer.
After 11 years of (follow up rate 86,1%) 4209 subject died; after 7 years (follow up rate 89,6%) 892 subject died for cardiovascular causes and 1134 for cancer.
“The green tea consumption was inversely associated with mortality due to all causes and due to cardiovascular disease” as the authors reported.
Conclusions were based on the multivariate hazard ratio of mortality due to all causes associated with different green tea consumption frequencies, a the decrease of the hazard ratio was found for all-causes and cardiovascular causes of mortality while the index parameter was not influenced by the green tea different consumption levels (less than 1 cup daily, for 1 to 2 cups/d, for 3 to 4 cups/d, for 5 or more cups/d.
In particular the inverse association was stronger in women respect to the male sex reaching a similar association value with a less cups intake (3-4 instead 5 or more).
The trend was even more favourable for both sex when associated with cardiovascular disease as death cause, especially for stroke.
Women were observed to reach a maximal decrease in hazard ratio at 3-4 cups/d (HR 0,69 – 95% CI, 0.52-0.93) instead 5 or more cups /d (HR 0,69 – 95% CI, 0,53-0,90).
Bibliography reference: S Kuriyama JAMA. 2006;296:1255-1265