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Am J Clin Nutr. 2019 Mar 1;109(3):597-605. doi: 10.1093/ajcn/nqy313.

Use of dietary supplements containing soy isoflavones and breast cancer risk among women aged >50 y: a prospective study.

Author information

Léon Bérard Cancer Center, UNICANCER, Lyon, France.
Cancer Research Centre of Lyon, French Institute of Health and Medical Research (INSERM) 1052, French National Centre for Scientific Research (CNRS) 5286, Lyon, France.
Center for Research in Epidemiology and Population Health (CESP), "Health across Generations" team, INSERM U1018, Villejuif, France.
CESP, University of Paris-Saclay, Villejuif, France.
Gustave Roussy, Villejuif, France, Neurocentre Magendie, Bordeaux, France.
University of Bordeaux, Physiopathologie de la plasticité neuronale, INSERM U1215, Neurocentre Magendie, Bordeaux, France.
Breast and Gynaecologic Cancer Registry of Cote d'Or, Georges-Francois Leclerc Cancer Centre, UNICANCER, Dijon, France.
Centre Hospitalier Universitaire (CHU) de Rennes, University of Rennes 1, Department of Endocrinology, Diabetology and Nutrition, Rennes, France.
International Agency for Research on Cancer, Section of Nutrition and Metabolism, Lyon, France.



Soy-based dietary supplements have been promoted as natural alternatives to menopausal hormone therapy, but their potential effect on breast cancer development is controversial.


We examined the relation between the consumption of soy supplements and the risk of breast cancer, overall and by tumor hormone receptor status, among women aged >50 y.


In total, 76,442 women from the Etude Epidemiologique aupres de Femmes de la Mutuelle Generale de l'Education Nationale (E3N) cohort, born between 1925 and 1950, were followed from 2000 to 2011 (11.2 y on average, starting at a mean age of 59.5 y; 3608 incident breast cancers), with soy supplement use assessed every 2-3 y. HRs of breast cancer were estimated with the use of multivariable Cox models.


Compared with never using soy supplements, the HRs associated with current use of soy supplements were 0.92 (95% CI: 0.76, 1.11) for all, 0.78 (95% CI: 0.60, 0.99) for estrogen receptor (ER)-positive, and 2.01 (95% CI: 1.41, 2.86) for ER-negative breast cancers. There was no association between past use of soy supplements and breast cancer. HRs for current use were 1.36 (95% CI: 0.95, 1.93) and 0.82 (95% CI: 0.65, 1.02) among women with and without a family history of breast cancer, respectively (P-interaction = 0.03) and 1.06 (95% CI: 0.87, 1.30) ≥5 y after menopause compared with 0.50 (95% CI: 0.31, 0.81) in premenopause or ≤5 y postmenopause (P-interaction = 0.04).


In this cohort of women aged >50 y, we report opposing associations of soy supplements with ER-positive and ER-negative breast cancer risk. Our results also caution against the use of these supplements in women with a family history of breast cancer. Whether the risk profile of soy supplements could be more favorable among premenopausal or recently postmenopausal women deserves further investigation.


breast cancer; cohort; dietary supplements; hormone receptors; isoflavones; prospective study; soy; women aged over 50 years

[Indexed for MEDLINE]

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