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Soy Intake and Insulin‐like Growth Factor‐I Levels among Women in Hawaii and Japan
Author(s) -
Takata Yumie,
Maskarinec Gertraud,
Nagata Chisato,
Rinaldi Sabina,
Kaaks Rudolph
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a597-b
Subject(s) - medicine , postmenopausal women , insulin like growth factor , breast cancer , endocrinology , isoflavones , estrogen , soy protein , cancer , growth factor , receptor , pathology
Insulin‐like growth factor‐I (IGF‐I) has been proposed as the link between diet and breast cancer risk. Due to their estrogen‐like structure, soy isoflavones may affect IGF‐I levels in a similar way as exogenous estrogens. In a cross‐sectional design, we compared IGF‐I levels between women with high and low soy intake. The analysis included 611 pre‐ and postmenopausal women: Japanese in Japan (JJ), and Japanese (JH) and Caucasians (CH) in Hawaii. The subjects had participated in a previous study, were never diagnosed with breast cancer, and provided a screening mammogram and blood sample. The same lab analyzed all serum samples for IGF‐I and IGF binding protein (IGFBP)‐3 by double‐antibody ELISA. Soy intake was assessed by validated food frequency questionnaires. We estimated mean IGF‐I and IGFBP‐3 levels by tofu intake after adjustment for covariates. The respective mean IGF‐I levels were 213, 257, and 255 ng/ml for JJ, JH, and CH. Tofu intake was higher among JJ than among JH and CH (11.0 vs. 9.4 and 4.9 g/1000kcal). Mean IGF‐I levels were 11% lower ( p = 0.01) and mean IGFBP‐3 levels were 5% higher ( p = 0.22) among women in the highest tofu intake category as compared to the lowest, but the relation was strongest among JJ women. These findings suggest that a diet rich in soy foods may be related to lower IGF‐I levels. This project was funded by NCI grants R03 CA105948 and R01 CA80843 and by AICR grant 02A021.