The relationships between
green tea and
black tea consumption and
colorectal cancer risk were examined within the Singapore Chinese Health Study, a prospective cohort study of diet and
cancer involving >60,000 men and women. Intake of
green tea and
black tea was assessed through in-person interviews. Incident
cancer cases and deaths among cohort members were identified through record linkage of the cohort database with respective databases from the nationwide Singapore
Cancer Registry and the Singapore Registry of Births and Deaths. The proportional hazard regression method was used to examine the associations between intake of green and
black tea separately and
colorectal cancer risk with adjustment for potential confounders. After an average of 8.9 years of follow-up, 845
colorectal cancer cases were identified. Subjects who drank
green tea exhibited a statistically non-significant increase in risk [relative risk (RR) = 1.12, 95% confidence interval (CI) = 0.97-1.29] relative to non-drinkers of
green tea. This risk increase was mainly confined to men (RR = 1.31, 95% CI = 1.08-1.58); the comparable RR in women was 0.89 (95% CI = 0.71-1.12). In men, the
green tea-
colorectal cancer association was noted mainly in those with advanced disease (Duke C or D) (RR = 1.53, 95% CI = 1.19-1.97), and the association was dose dependent (P for trend = 0.0002). This latter association was especially strong within the colon subsite (RR = 1.75, 95% CI = 1.24-2.46; P for trend < 0.0001). Irrespective of gender, intake of
black tea was not associated with risk of
colorectal cancer (RR = 0.92, 95% CI = 0.79-1.07) in this Asian population.