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Association of soy and fermented soy product intake with total and cause specific mortality: prospective cohort study

BMJ 2020; 368 doi: (Published 29 January 2020) Cite this as: BMJ 2020;368:m34

Linked Editorial

Soy intake and health

  1. Ryoko Katagiri, scientist1,
  2. Norie Sawada, section chief1,
  3. Atsushi Goto, section chief1,
  4. Taiki Yamaji, section chief1,
  5. Motoki Iwasaki, division chief1,
  6. Mitsuhiko Noda, professor2,
  7. Hiroyasu Iso, professor3,
  8. Shoichiro Tsugane, director1
  9. for the Japan Public Health Center-based Prospective Study Group
  1. 1Epidemiology and Prevention Group, Center for Public Health Sciences, National Cancer Centre, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045, Japan
  2. 2Department of Diabetes, Metabolism and Endocrinology, Ichikawa Hospital, International University of Health and Welfare, Ichikawa, Chiba, Japan
  3. 3Public Health, Department of Social Medicine, Osaka University Graduate School of Medicine, Suita-shi, Osaka, Japan
  1. Correspondence to: N Sawada nsawada{at}
  • Accepted 16 December 2019


Objective To investigate the association between several types of soy products and all cause and cause specific mortality.

Design Population based cohort study.

Setting Japan Public Health Centre-based Prospective Study, which includes 11 public health centre areas in Japan.

Participants 92 915 participants (42 750 men and 50 165 women) aged 45 to 74 years.

Exposures Intake of total soy products, fermented soy products (natto and miso), non-fermented soy products, and tofu from a five year survey questionnaire.

Main outcome measures All cause and cause specific mortality (cancer, total cardiovascular disease, heart disease, cerebrovascular disease, respiratory disease, and injury) obtained from residential registries and death certificates.

Results During 14.8 years of follow-up, 13 303 deaths were identified. In the multivariable adjusted models, intake of total soy products was not significantly associated with total mortality. Compared with the lowest fifth of total soy product intake, the hazard ratios in the highest fifth were 0.98 (95% confidence interval 0.91 to 1.06, Ptrend=0.43) in men and 0.98 (0.89 to 1.08, Ptrend=0.46) in women. Intake of fermented soy products was inversely associated with all cause mortality in both sexes (highest versus lowest fifth: 0.90 (0.83 to 0.97), Ptrend=0.05 in men, and 0.89 (0.80 to 0.98), Ptrend=0.01 in women). Natto showed significant and inverse associations with total cardiovascular disease related mortality in both sexes.

Conclusions In this study a higher intake of fermented soy was associated with a lower risk of mortality. A significant association between intake of total soy products and all cause mortality was not, however, observed. The findings should be interpreted with caution because the significant association of fermented soy products might be attenuated by unadjusted residual confounding.


  • Contributors: ST designed the study as the principal investigator. ST, NS, YT, MI, MN, and HI conducted the survey. RK, NS, and AG drafted the plans for the data analyses. RK conducted data analysis and drafted the manuscript. All authors were involved in interpretation of the results and revision of the manuscript, and all approved the final version of the manuscript. RK and NS are guarantors. The corresponding author attests that all the listed authors meet the authorship criteria and that no others meeting the criteria have been omitted.

  • Funding: This study was supported by National Cancer Center research and development fund (since 2011) and a grant-in-aid for cancer research from the Japanese Ministry of Health, Labour, and Welfare (1989 to 2010). The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.

  • Competing interests: All authors have completed the ICMJE uniform disclosure form at and declare: no support from any organisation for the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; and no other relationships or activities that could appear to have influenced the submitted work.

  • Ethical approval: This study was approved by the institutional review board of the National Cancer Centre, Japan (No 2001-021, 2015-085).

  • Data sharing: For information on how to submit an application for gaining access to Japan Public Health Centre-based Prospective Study data, follow the instructions at

  • The study guarantors (RK and NS) affirm that the manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as planned have been explained.

  • Dissemination to participants and related patient and public communities: The results of this research were reported in newsletters for study participants and on the study website ( and public lectures about disease prevention have been provided based on the results.

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