Elsevier

Annals of Epidemiology

Volume 25, Issue 7, July 2015, Pages 512-518.e3
Annals of Epidemiology

Original article
Association of green tea consumption with mortality due to all causes and major causes of death in a Japanese population: the Japan Public Health Center-based Prospective Study (JPHC Study)

https://doi.org/10.1016/j.annepidem.2015.03.007Get rights and content

Highlights

  • Green tea is most popularly consumed in Japan and known to contain many beneficial compounds

  • We studied 90,914 Japanese aged between 40 and 69 years during 1990 to 1994.

  • We examine associations between green tea, caffeine intake, and five leading causes of death in Japan.

  • Inverse associations between green tea and caffeine intake and mortality due to major causes of deaths are reported.

  • We discuss possible mechanisms for the health benefits of green tea.

Abstract

Purpose

We examined the association between green tea consumption and mortality due to all causes, cancer, heart disease, cerebrovascular disease, respiratory disease, injuries, and other causes of death in a large-scale population-based cohort study in Japan.

Methods

We studied 90,914 Japanese (aged between 40 and 69 years) recruited between 1990 and 1994. After 18.7 years of follow-up, 12,874 deaths were reported. The association between green tea consumption and risk of all causes and major causes of mortality was assessed using the Cox proportional hazards regression model with adjustment for potential confounders.

Results

Hazard ratios for all-cause mortality among men who consumed green tea compared with those who drank less than 1 cup/day were 0.96 (0.89–1.03) for 1–2 cups/day, 0.88 (0.82–0.95) for 3–4 cups/day, and 0.87 (0.81–0.94) for more than 5 cups/day (P for trend <.001). Corresponding hazard ratios for women were 0.90 (0.81–1.00), 0.87 (0.79–0.96), and 0.83 (0.75–0.91; P for trend <.001). Green tea was inversely associated with mortality from heart disease in both men and women and mortality from cerebrovascular disease and respiratory disease in men. No association was found between green tea and total cancer mortality.

Conclusions

This prospective study suggests that the consumption of green tea may reduce the risk of all-cause mortality and the three leading causes of death in Japan.

Introduction

Tea is one of the most popular beverages consumed globally and in Japan. Among different kinds of tea, 53% of Japanese adults drink green tea every day [1]. Green tea contains many compounds that are beneficial for health, including caffeine and polyphenol catechins [2]. Because green tea is regularly consumed throughout life, the health effects of these compounds may accumulate to make a large effect on the longevity of the general population.

Epidemiologic studies of the associations between green tea and mortality events have been reported, but most of them are limited to all-cause, stroke, or cardiovascular disease mortality [3], [4]. Only one large-scale cohort study has shown an inverse association between green tea and deaths due to pneumonia [5], and for total cancer mortality, past studies have shown conflicting results [3], [4], [6]. In contrast, no prospective cohort studies reported the effect of green tea on injury-related deaths, although total injury deaths including accidents and suicide account for 5.9% of mortality and rank the fifth of the major causes of death in Japan [7]. It means that no study has comprehensively assessed the effect of green tea consumption on five leading causes of death, which may contribute to explain the prolonged life expectancy in Japan. We aim to investigate the potential benefits of the most commonly consumed beverage on five leading causes of death in Japan, thereby suggesting health promotion strategies that can be implemented with minimal costs to the national health systems.

Section snippets

Study population

The details of the Japan Public Health Center-based Prospective Study have been reported elsewhere [8], [9], [10]. The study commenced in 1990 for cohort I and in 1993 for cohort II, covering a total of 140,420 individuals (68,722 men and 71,698 women) in 11 public health center areas. Cohort I included individuals aged between 40 and 59 years, whereas cohort II identified individuals aged between 40 and 69 years. Participants with non-Japanese nationality (n = 51), incorrect birth date (n

Results

Table 1 and Supplemental Table 1 summarize the baseline characteristics of participants by green tea consumption status. Participants who consumed more green tea were likely to be older, tended to practice sports or physical exercise, and tended to smoke and drink less, but reported a higher prevalence of hypertension and diabetes in both men and women.

During the follow-up period (18.7 years on average, total person-years 1,699,305), a total of 12,874 deaths were reported. Of these, 5327 deaths

Discussion

This is the first study to assess the associations between green tea intake and five major leading causes of mortality in a large prospective cohort study. Compared with participants who drank less than one cup of green tea a day, those who drank 5 cups/day or more had 13% lower risk of dying from all causes in men and 17% lower risk in women. Our findings on total mortality corroborate those of other large-scale, prospective cohort studies [3], [6].

We also found that consumption of green tea

Conclusion

This prospective cohort study showed inverse associations between consumption of green tea, total mortality, and three out of five leading causes of death, including deaths from heart disease, cerebrovascular disease, and respiratory disease. Further studies are required to confirm the association of green tea with injury-related mortality from well-designed clinical trials.

Acknowledgments

This study was supported by the National Cancer Center Research and Development Fund (23-A-31[toku] and 26-A-2; since 2011), by a Grant-in-Aid for Cancer Research from the Ministry of Health, Labor and Welfare of Japan (from 1989 to 2010) and by Health and Labor Sciences Research Expenses for Commission (Comprehensive Research on Life-Style Related Diseases including Cardiovascular Diseases and Diabetes Mellitus H26-005). Members of the Japan Public Health Center-based Prospective Study (JPHC

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    M.I. is the beneficiary of a financial contribution from the AXA Research Fund as chair holder of the AXA Department of Health and Human Security, Graduate School of Medicine, The University of Tokyo. The AXA Research Fund had no role in the design, data collection, analysis, interpretation or manuscript drafting, or in the decision to submit the manuscript for publication. The authors declare no other conflicts of interest.

    1

    Address reprint requests. Research Centre for Cancer Prevention and Screening, National Cancer Centre, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045, Japan.

    2

    Study group members are listed in the Acknowledgment.

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