Nutr Res Pract.  2025 Feb;19(1):80-95. 10.4162/nrp.2025.19.1.80.

Dietary isoflavone intake among breast cancer survivors and cancer-free women

• Song S
• Moon HG
• Noh DY
• Jung SY
• Lee ES
• Kim Z
• Youn HJ
• Cho J
• Yoo YB
• Lee SK
• Lee JE
• Nam SJ
• Kim YS
• Min JW
• Jun S
• Joung H
• Lee JE

• KMID: 2565398
• DOI: http://doi.org/10.4162/nrp.2025.19.1.80

Abstract

BACKGROUND/OBJECTIVES
Isoflavones are estrogen-like compounds found in plants and their health effects remain equivocal. We investigated dietary isoflavone intake and its associated factors in Korean breast cancer survivors, with a comparison to cancer-free women.
SUBJECTS/METHODS
The usual dietary intake of breast cancer survivors (n = 981, mean age 52 yrs) in 9 hospitals between 2012 and 2019 was assessed using 3-day food records or food frequency questionnaires (FFQs). They were age-matched to 2,943 cancer-free women who completed FFQs as part of a nationwide study conducted between 2012 and 2016. We used the flavonoid database of common Korean foods and the Phenol-Explorer database to estimate isoflavone intake. The contribution of each food or food group to the total isoflavone intake was calculated. The adjusted least-squares means of dietary isoflavone intake according to lifestyle and clinical factors were calculated using generalized linear models.
RESULTS
Breast cancer survivors had a higher mean dietary isoflavone intake (23.59 mg/day) than cancer-free women (17.81 mg/day). Major food sources, including tofu, soybeans, and doenjang, contributed to over 70% of the isoflavone intake in both groups. When we estimated dietary isoflavone intake according to lifestyle characteristics, isoflavone intake increased with higher scores of adherence to the American Cancer Society dietary guidelines but decreased with increasing body mass index in both groups. Among cancer-free women, dietary isoflavone intake was higher among those who had never smoked and among dietary supplement users. Among breast cancer survivors, dietary isoflavone intakes did not vary with clinical characteristics, including time since surgery and estrogen receptor status.
CONCLUSION
Breast cancer survivors were more likely to consume isoflavones than agematched cancer-free women. Dietary isoflavone intake was associated with healthy lifestyle characteristics in women both with and without breast cancer. Further research is needed to understand the role of the higher isoflavone intake among breast cancer survivors compared to cancer-free women on their prognosis.

Keyword

Isoflavones; soy foods; breast cancer

Figure

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  Fig. 1 Flowchart of the study population. For each breast cancer survivor, 3 cancer-free women were randomly age-matched.3-DFRs, 3-day food records; FFQs, food frequency questionnaires; KNHANES, Korea National Health and Nutrition Examination Survey.

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