Tea polyphenols have consistently demonstrated leukemic-inhibition in numerous vivo and vitro studies [1-6]. However, epidemiologic studies on the association between tea consumption and adult leukemia risk are limited and inconclusive [7-12].
A case-control study conducted in China between 2008 and 2012 to investigate the association between tea consumption and adult leukemia risk.
This included 493 incident, hematologically confirmed leukemia cases and 493 outpatient controls matched to each case by gender, year-of-birth quinquennium, and study site. Information on type, duration, frequency, and quantity of tea consumption, diet, lifestyle, and demographic characteristics was collected by face-to-face interview using a reliable structured questionnaire. Odds ratios (ORs) were estimated using conditional logistic regression after adjusted for resident locality, education, tobacco smoking, alcohol consumption, and fruits intake.
Among cases with leukemia subtype information (414 out of 493), 67.6% were acute myeloid leukemia, 16.9% acute lymphoblastic leukemia, 10.4% chronic myeloid leukemia, and 5.1% chronic lymphocytic leukemia. There were 49.5% of the cases who drank tea compared with 65.9% of the controls. Among tea drinkers, 95.8% reported drinking green tea only or green tea with black or oolong tea. Compared with non-tea drinkers, the adjusted ORs (95% confidence intervals) were 0.30 (0.17-0.54), 0.26 (0.16-0.42), and 0.28 (0.17-0.47) for those who consumed tea ≥30 years, ≥2 cups daily, and dried tealeaves >1000g annually, respectively. A significant inverse relationship was observed across all tea measurements with a statistically significant test for trend (P <0.001). In analysis of leukaemia subtype, higher tea consumption was associated with a lower risk of acute myeloid leukaemia. The inverse association existed in both males and females after stratification, and a greater risk reduction was observed in females.
We conclude that regular daily consumption of green tea can protect against adult leukemia.