Relationship of serum levels and dietary intake of isoflavone, and the novel bacterium Slackia sp. strain NATTS with the risk of prostate cancer: a case-control study among Japanese men.
OBJECTIVE
Isoflavones may play a role in the prevention of hormone-related cancers. Equol is an isoflavone metabolized from daidzein in the presence of certain intestinal bacteria. Slackia sp. strain NATTS, a newly identified equol-producing bacterium, was recently isolated from human feces in Japan. We investigated the association of serum levels and dietary intake of isoflavones and Slackia sp. strain NATTS with the risk of prostate cancer in a case-control study among Japanese men.


METHODS
Fifty-six patients with newly diagnosed prostate cancer and 56 hospital controls were enrolled in this study. Isoflavones were assessed by measurement of serum levels and administration of a food frequency questionnaire. Slackia sp. strain NATTS in feces was also measured. The odds ratios (ORs) and 95 % confidence intervals (CIs) for prostate cancer were then determined using a logistic regression model.


RESULTS
The adjusted ORs for prostate cancer in comparison with the highest to lowest categories were 0.06 (95 % CI 0.02-0.24) for serum genistein, 0.18 (95 % CI 0.06-0.52) for daidzein, 0.16 (95 % CI 0.06-0.46) for glycitein, 0.52 (95 % CI 0.22-1.22) for equol, 0.86 (95 % CI 0.30-2.48) for dietary genistein, and 0.80 (95 % CI 0.28-2.28) for dietary daidzein. The adjusted OR for prostate cancer in comparison with values above versus below the median was 0.95 (95 % CI 0.42-2.16) for Slackia sp. strain NATTS.


CONCLUSIONS
Our study findings suggest that high serum levels of genistein, daidzein, and glycitein are significantly associated with a decreased risk of prostate cancer among Japanese men.
Department of Public Health, Sapporo Medical University School of Medicine, West-17, South-1, Chuo-ku, Sapporo, 060-8556, Japan. ynagata@sapmed.ac.jp.
Yoshie
Y
Nagata
Department of Public Health, Sapporo Medical University School of Medicine, West-17, South-1, Chuo-ku, Sapporo, 060-8556, Japan.
Yukiko
Y
Sugiyama
Department of Urology, Sapporo Medical University School of Medicine, West-17, South-1, Chuo-ku, Sapporo, 060-8556, Japan.
Fumimasa
F
Fukuta
Department of Urology, Sapporo Medical University School of Medicine, West-17, South-1, Chuo-ku, Sapporo, 060-8556, Japan.
Akio
A
Takayanagi
Department of Urology, Sapporo Medical University School of Medicine, West-17, South-1, Chuo-ku, Sapporo, 060-8556, Japan.
Naoya
N
Masumori
Department of Urology, Sapporo Medical University School of Medicine, West-17, South-1, Chuo-ku, Sapporo, 060-8556, Japan.
Taiji
T
Tsukamoto
Department of Cardiovascular, Renal and Metabolic Medicine, Sapporo Medical University School of Medicine, West-17, South-1, Chuo-ku, Sapporo, 060-8556, Japan.
Hiroshi
H
Akasaka
Department of Public Health, Sapporo Medical University School of Medicine, West-17, South-1, Chuo-ku, Sapporo, 060-8556, Japan.|Department of Cardiovascular, Renal and Metabolic Medicine, Sapporo Medical University School of Medicine, West-17, South-1, Chuo-ku, Sapporo, 060-8556, Japan.
Hirofumi
H
Ohnishi
Department of Nursing, Sapporo Medical University School of Health Sciences, West-17, South-1, Chuo-ku, Sapporo, 060-8556, Japan.
Shigeyuki
S
Saitoh
Department of Cardiovascular, Renal and Metabolic Medicine, Sapporo Medical University School of Medicine, West-17, South-1, Chuo-ku, Sapporo, 060-8556, Japan.
Tetsuji
T
Miura
Yakult Central Institute for Microbiological Research, Izumi 5-11, Kunitachi, Tokyo, 186-0012, Japan.
Kaoru
K
Moriyama
Yakult Central Institute for Microbiological Research, Izumi 5-11, Kunitachi, Tokyo, 186-0012, Japan.
Hirokazu
H
Tsuji
Research Center for Advanced Science and Technology, The University of Tokyo, Komaba 4-6-1, Meguro-ku, Tokyo, 153-8904, Japan.
Hideyuki
H
Akaza
Department of Public Health, Sapporo Medical University School of Medicine, West-17, South-1, Chuo-ku, Sapporo, 060-8556, Japan.
Mitsuru
M
Mori
D039903:Actinobacteria / Q000302:isolation & purification*; D000368:Aged; D016022:Case-Control Studies; D004032:Diet; D060754:Equol / Q000097:blood; D005243:Feces / Q000382:microbiology; D019833:Genistein / Q000097:blood; D006801:Humans; D007529:Isoflavones / Q000097:blood*; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D011471:Prostatic Neoplasms / Q000097:blood* / Q000453:epidemiology / Q000382:microbiology; D011795:Surveys and Questionnaires
D007529:Isoflavones; D060754:Equol; C004742:daidzein; C086566:glycitein; D019833:Genistein
Dietary isoflavone intake; Japanese men; Prostate cancer; Serum isoflavone level; Slackia sp. strain NATTS