Soy intake and breast cancer risk: a prospective study of 300,000 Chinese women and a dose–response meta-analysis

China Kadoorie Biobank (CKB) collaborative group

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    Epidemiological evidence on the association of soy intake with breast cancer risk is still inconsistent due to different soy intake levels across previous studies and small number of breast cancer cases. We aimed to investigate this issue by analyzing data from the China Kadoorie Biobank (CKB) study and conducting a dose–response meta-analysis to integrate existing evidence. The CKB study included over 300,000 women aged 30–79 from 10 regions across China enrolled between 2004 and 2008, and followed-up for breast cancer events until 31 December 2016. Information on soy intake was collected from baseline, two resurveys and twelve 24-h dietary recalls. We also searched for relevant prospective cohort studies to do a dose–response meta-analysis. The mean (SD) soy intake was 9.4 (5.4) mg/day soy isoflavones among CKB women. During 10 years of follow-up, 2289 women developed breast cancers. The multivariable-adjusted relative risk was 1.00 (95% confidence interval [CI] 0.81–1.22) for the fourth (19.1 mg/day) versus the first (4.5 mg/day) soy isoflavone intake quartile. Meta-analysis of prospective studies found that each 10 mg/day increment in soy isoflavone intake was associated with a 3% (95% CI 1–5%) reduced risk of breast cancer. The CKB study demonstrated that moderate soy intake was not associated with breast cancer risk among Chinese women. Higher amount of soy intake might provide reasonable benefits for the prevention of breast cancer.

    Original languageEnglish
    Pages (from-to)567-578
    Number of pages12
    JournalEuropean Journal of Epidemiology
    Issue number6
    Early online date21 Nov 2019
    Publication statusPublished - Jun 2020

    Bibliographical note

    This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativeco, which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate
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    This work was supported by Grants (81530088, 81390540, 81390544, 81390541) from National Natural Science Foundation of China; (2016YFC0900500, 2016YFC0900501, 2016YFC0900504, 2016YFC130390 4 ) from the National Key Research and Development Program of China; a grant from the Kadoorie Charitable Foundation in Hong Kong; Grants from the UK Wellcome Trust (202922/Z/16/Z, 088158/Z/09/Z, 104085/Z/14/Z); Grants from Chinese Ministry of Science and Technology (2011BAI09B01); and Breast Cancer Research Foundation. The funders and sponsors of the study had no role in the study design and conduct, data collection, data analysis, data interpretation, writing of the report, or the decision to submit the manuscript for publication. The corresponding author had full access to all the data in the study and had final responsibility for the decision to submit for publication.

    Publisher Copyright:
    © 2019, The Author(s).


    • Breast cancer
    • Dose–response meta-analysis
    • Prospective cohort study
    • Soy intake

    ASJC Scopus subject areas

    • Epidemiology


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