Habitual green tea consumption and risk of an aneurysmal rupture subarachnoid hemorrhage: a case-control study in Nagoya, Japan.

BACKGROUND

Green tea, a popular beverage in Japan, contains many polyphenolic antioxidants, which might prevent cardiovascular disease. This study is designed to determine whether the consumption of green tea is associated with a reduced risk for subarachnoid hemorrhage (SAH) using a case-control study.

METHODS

Incident SAH cases (n=201) were identified and individually matched by age (+/-2 years) and gender to hospital (n=201) and community controls (n=201) from April 1992 to March 1997. Habitual regular tea consumption was assessed with a structured questionnaire. Conditional logistic regression models were used to compute odds ratios adjusted for smoking, history of hypertension, and educational levels.

RESULTS

The proportion of the consumption of one time or more of tea per day was higher in controls (70.9%) than in SAH patients (60.3%). Multivariate analyses showed that green tea consumption was inversely associated with SAH risk. Subjects consuming <1, and >or=1 time per day had adjusted ORs of 0.74 (CI: 0.34-1.58), and 0.56 (CI: 0.32-0.98) in comparison with non daily green tea drinkers, respectively (p-trend <0.001).

CONCLUSIONS

In a case-control study in Japan, we found that habitual green tea consumption may be strongly associated with a reduced risk for SAH. Our findings will be useful in targeting individuals and populations for the primary prevention of SAH.