Cancer-preventive effects of drinking green tea among a Japanese population

Prev Med. 1997 Nov-Dec;26(6):769-75. doi: 10.1006/pmed.1997.0242.


Background: Laboratory studies have revealed the cancer preventive effects of green tea, so the association between green tea consumption and cancer was examined in a human population.

Methods: The association between green tea consumption and cancer incidence was studied in our prospective cohort study of a Japanese population. We surveyed 8,552 individuals over 40 years of age living in a town in Saitama prefecture on their living habits, including daily consumption of green tea. During the 9 years of follow-up study (71,248.5 person-years), we identified a total of 384 cases of cancer in all sites.

Results: We found a negative association between green tea consumption and cancer incidence, especially among females drinking more than 10 cups a day. The slowdown in increase of cancer incidence with age observed among females who consumed more than 10 cups a day is consistent with the finding that increased consumption of green tea is associated with later onset of cancer. Age-standardized average annual incidence rate was significantly lower among females who consumed large amounts of green tea. Relative risk (RR) of cancer incidence was also lower among both females (RR = 0.57, 95% CI = 0.33-0.98) and males (RR = 0.68, 95% CI = 0.39-1.21) in groups with the highest consumption, although the preventive effects did not achieve statistical significance among males, even when stratified by smoking and adjusted for alcohol and dietary variables.

Conclusion: Our epidemiological study showed that green tea has a potentially preventive effect against cancer among humans.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Age Distribution
  • Aged
  • Diet Surveys
  • Diet*
  • Female
  • Humans
  • Incidence
  • Japan / epidemiology
  • Male
  • Middle Aged
  • Neoplasms / epidemiology*
  • Neoplasms / prevention & control*
  • Prospective Studies
  • Risk
  • Risk Factors
  • Sex Distribution
  • Tea*
  • Urban Health


  • Tea