Counts of Slackia sp. strain NATTS in intestinal flora are correlated to serum concentrations of equol both in prostate cancer cases and controls in Japanese men.
BACKGROUND
Isoflavones, which are included in soybeans, have been suggested to protect against prostate cancer. Equol, one of isoflavones, is an intestinally derived bacterial metabolite of daidzein. A newly identified equol-producing bacterium, Slackia sp. strain NATTS, with a high equol-producing activity was isolated from human feces in Japanese adults. Counts of Slackia sp. strain NATTS in intestinal flora have not been assessed with regard to prostate cancer risk. In this study, we investigated the association of serum isoflavones and counts of Slackia sp. strain NATTS with prostate cancer risk in a case-control study.


METHODS
Concentrations of isoflavones and counts of Slackia sp. strain NATTS in feces were measured from 44 patients with prostate cancer and 28 hospital controls. The risk of prostate cancer was evaluated in terms of odds ratios (ORs) and 95% confidence intervals (CIs) by the logistic regression analysis.


RESULTS
The detection proportions of Slackia sp. strain NATTS in cases and controls were 34.1% and 25.0%, respectively. Counts of Slackia sp. strain NATTS were significantly correlated with serum concentrations of equol both in cases and controls (Spearman correlation coefficients, rs=0.639 and rs=0.572, p<0.01, respectively). Serum concentrations of genistein, daidzein, glycitein, and equol were not significantly associated with risk of prostate cancer.


CONCLUSIONS
This study found that counts of Slackia sp. strain NATTS correlated with serum concentrations of equol both in prostate cancer cases and controls, but serum isoflavone concentrations were not associated with risk of prostate cancer in our patients.
Department of Public Health, Sapporo Medical University School of Medicine, Sapporo, Japan E-mail : ysugi@sapmed.ac.jp.
Yukiko
Y
Sugiyama
Yoshie
Y
Nagata
Fumimasa
F
Fukuta
Akio
A
Takayanagi
Naoya
N
Masumori
Taiji
T
Tsukamoto
Hiroshi
H
Akasaka
Hirofumi
H
Ohnishi
Shigeyuki
S
Saito
Tetsuji
T
Miura
Kaoru
K
Moriyama
Hirokazu
H
Tsuji
Hideyuki
H
Akaza
Mitsuru
M
Mori
D039903:Actinobacteria / Q000254:growth & development / Q000378:metabolism*; D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D060754:Equol / Q000097:blood*; D005243:Feces / Q000382:microbiology; D005500:Follow-Up Studies; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism*; D007422:Intestines / Q000382:microbiology*; D007529:Isoflavones / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011471:Prostatic Neoplasms / Q000097:blood* / Q000382:microbiology / Q000473:pathology
D007529:Isoflavones; D060754:Equol; C004742:daidzein