green tea flowerTea consumption began in China around 2737 B.C. and has since become a staple among Asian and English cultures. The use of tea for medicinal purposes have prevailed for centuries in traditional Chinese medicine, but only recently gained prominence in the modern “alternative medicine” community. There has been increased interest and active biomedical research on tea extracts, with dozens of peer-reviewed scientific articles published each month exploring the health properties of green tea. Through in vitro and animal studies, green tea (derived from the Camellia sinensis plant) and its polyphenol compounds — in particular, epigallocatechin-3-gallate (EGCG) — have been associated with possible risk reductions in some cardiovascular, neurologic, and oncologic disorders. Human trials are however sparse or equivocal.

I previously reported on a Japanese study correlating green tea consumption with a lower prevalence of cognitive dysfunction. A similar research group from the Tohoku University School of Medicine (Sendai, Japan) has continued to analyze the benefits of green tea with other health outcomes: causes of mortality, cardiovascular disease, pneumonia, and cancers. Their most recent study, published in the American Journal of Epidemiology, evaluated the influence of green tea consumption on the development of hematologic malignancies.


The study cohort included 41,761 Japanese adults aged 40-79 years, who were registered under the Ohsaki National Health Insurance (NHI). The participants completed self-administered questionnaires on diverse topics, including dietary intake. Their health histories were obtained from the Myagi Prefecture Cancer Registery, supposedly “one of the oldest and most accurate population-based cancer registeries in Japan”. The researchers were particularly interested in recording the incidence of hematologic malignancies, such as Hodgkin and non-Hodgkin lymphomas, plasma cell tumors, mast cell tumors, immunoproliferative disease, myelodysplastic syndromes, etc. The follow-up period was 9 years.

The study found that “green tea consumption was inversely associated with the risk of hematologic malignancies“. Multivariate-adjusted hazard ratios for those who consumed more green tea (5 cups/day compared to <1 cup/day) was 0.58 (95% CI: 0.37-0.89) for all hematologic malignancies and 0.52 (95% CI: 0.31-0.87) for lymphoid neoplasms. These were equivalent to 42% and 48% risk-reductions, respectively. Although the multivariate-adjusted hazard ratio for myeloid neoplasms was 0.76, the 95% confidence interval was broad (0.32-1.78).

There may have been confounding factors. Those who drank more green tea tended to also eat more fish and soybean products. Men who consumed more green tea were also less likely to be alcoholic, smokers, or obese; these relationships were not present among women. The researchers acknowledge that their study was also limited by a 13% attrition rate of participants, exclusion of 6,337 participants due to incomplete answers, lower overall rate of hematologic malignancies compared to Western nations, possible recording or accounting errors of the Miyagi Cancer Registry, and unavailable data on occupational exposures.

Despite the limitations of the study and the current dearth of data to firmly attribute any anti-tumorigenic effects to green tea, the findings contribute to the overall body of evidence favoring the health benefits of green tea. It would not be unreasonable to imagine that there may one day be an FDA-approved green tea drug (”the green pill”) for the pharmacologic management of a specific disorder (I’m not talking about those Black Cohosh or echinacea herbal-type remedies found at the GNC store). Many popular prescription and over-the-counter drugs today originated from humble plants: aspirin from the willow bark, quinine from the cinchona bark, and digoxin from foxglove. Hmm … I wonder whether I should start saving money to purchase stock when the next blockbuster GreenteagraTM or greentealeafil (generic form) hits the market. Probably not.

  • Sources
  • Kuriyama S, Hozawa A, Ohmori K, Shimazu T, Matsui T, Ebihara S, Awata S, Nagatomi R, Arai H, Tsuji I. Green tea consumption and cognitive function: a cross-sectional study from the Tsurugaya Project. Am J Clin Nutr 2006;83:355-61.
  • Naganuma T, Kuriyama S, Kakizaki M, Sone T, Nakaya N, Ohmori-Matsuda K, Hozawa A, Nishino Y, & Tsuji I (2009). Green Tea Consumption and Hematologic Malignancies in Japan: The Ohsaki Study. American journal of epidemiology PMID: 19640889