Association of serum phytoestrogen concentration and dietary habits in a sample set of the JACC Study.
BACKGROUND
Phytoestrogens may be associated with a reduced risk of hormone dependent neoplasms such as prostate and breast cancers. We tried to determine the validity of the association between serum phytoestrogen concentrations and dietary habits obtained from a food frequency questionnaire used in the Japan Collaborative Cohort Study (JACC Study) for Evaluation of Cancer Risk sponsored by the Ministry of Education, Science, Sports and Culture of Japan (Monbusho).


METHODS
The subjects were 151 male controls who were selected for a nested case-control study for evaluating prostate cancer risk as part of the JACC Study. Dietary habits were determined using a food frequency questionnaire at baseline, and the concentrations of genistein, daidzein, and equol in frozenstored serum samples assayed in 2002 were compared.


RESULTS
Tofu intake showed a significant association with the serum concentrations of genistein and daidzein (Spearman's correlation coefficients (rs)=0.30 and 0.27, respectively), and miso soup showed a slight association with serum concentrations of these phytoestrogens. In contrast, serum concentrations of equol were not associated with dietary intake of tofu and miso soup. After adjustment for serum daidzein concentration, serum equol concentration was associated with the intake of foods containing fat, meat, and coffee, but not green tea.


CONCLUSIONS
Serum genistein and daidzein concentrations were significantly associated with dietary intake of tofu, and slightly with intake of miso soup. Consumption of fat, meat, and coffee may be associated with equol production by intestinal microflora in this sample set.
Ozasa
Kotaro
K
Department of Epidemiology for Community Health and Medicine, Kyoto Prefectural University of Medicine Graduate School of Medical Science, Japan. kozasa@koto.kpu-m.ac.jp
Nakao
Masahiro
M
Watanabe
Yoshiyuki
Y
Hayashi
Kyohei
K
Miki
Tsuneharu
T
Mikami
Kazuya
K
Mori
Mitsuru
M
Sakauchi
Fumio
F
Washio
Masakazu
M
Ito
Yoshinori
Y
Suzuki
Koji
K
Kubo
Tatsuhiko
T
Wakai
Kenji
K
Tamakoshi
Akiko
A
D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D015331:Cohort Studies; D004034:Diet Surveys; D005247:Feeding Behavior; D019833:Genistein / Q000097:blood*; D006801:Humans; D007529:Isoflavones / Q000096:biosynthesis*; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009752:Nutritional Status; D048789:Phytoestrogens / Q000008:administration & dosage / Q000097:blood*; D011471:Prostatic Neoplasms / Q000453:epidemiology*; D045730:Soy Foods; D011795:Surveys and Questionnaires
D007529:Isoflavones; D048789:Phytoestrogens; C004742:daidzein; D019833:Genistein