Effects of a diet rich in phytoestrogens on prostate-specific antigen and sex hormones in men diagnosed with prostate cancer.
OBJECTIVE
To determine the effects of diets rich in soy and linseed compared with a control diet on biochemical markers of prostate cancer in men diagnosed with prostate cancer.


METHODS
Twenty-nine men diagnosed with prostate cancer and scheduled to undergo a radical prostatectomy were randomized to one of three groups: soy (high phytoestrogen), soy and linseed (high phytoestrogen), or wheat (low phytoestrogen). A bread was specially manufactured to incorporate 50 g of heat-treated (HT) soy grits or 50 g of HT soy grits and 20 g of linseed as part of the study participant's daily diet. Baseline and preoperative levels of prostate-specific antigen (PSA), free PSA, testosterone, sex hormone-binding globulin, free androgen index, and dihydrotestosterone were measured.


RESULTS
Statistically significant differences were detected between the HT soy grits group and the control wheat group for the percentage of change in total PSA (-12.7% versus 40%, P = 0.02) and the percentage of change in free/total PSA ratio (27.4% versus -15.6%, P = 0.01); and between the HT soy grits group and the HT soy grits and linseed group for the percentage of change in free androgen index (16.4% versus -15.5%, P = 0.04) and the percentage of change in free/total PSA ratio (27.4% versus -10%, P = 0.007).


CONCLUSIONS
The data from this study indicate that a daily diet containing four slices of a bread rich in HT soy grits favorably influences the PSA level and the free/total PSA ratio in patients with prostate cancer. This work provides some evidence to support epidemiologic studies claiming that male populations who consume high phytoestrogen diets have a reduced risk of prostate cancer development and progression.
Dalais
Fabien S
FS
International Health and Development Unit, Monash University, Clayton, VIC, Australia.
Meliala
Andreanyta
A
Wattanapenpaiboon
Naiyana
N
Frydenberg
Mark
M
Suter
David A I
DA
Thomson
William K
WK
Wahlqvist
Mark L
ML
D000230:Adenocarcinoma / Q000097:blood / Q000178:diet therapy*; D000368:Aged; D000728:Androgens / Q000097:blood; D014408:Biomarkers, Tumor / Q000097:blood*; D001939:Bread / Q000032:analysis; D013196:Dihydrotestosterone / Q000097:blood; D004311:Double-Blind Method; D019597:Flax / Q000009:adverse effects; D019833:Genistein / Q000032:analysis; D012739:Gonadal Steroid Hormones / Q000097:blood*; D006801:Humans; D007529:Isoflavones / Q000032:analysis / Q000652:urine; D008297:Male; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000097:blood*; D048789:Phytoestrogens / Q000008:administration & dosage / Q000627:therapeutic use*; D008517:Phytotherapy; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000097:blood / Q000178:diet therapy*; D012738:Sex Hormone-Binding Globulin / Q000032:analysis; D045730:Soy Foods; D013739:Testosterone / Q000097:blood
D000728:Androgens; D014408:Biomarkers, Tumor; D012739:Gonadal Steroid Hormones; D007529:Isoflavones; D009363:Neoplasm Proteins; D048789:Phytoestrogens; D012738:Sex Hormone-Binding Globulin; D013196:Dihydrotestosterone; D013739:Testosterone; C004742:daidzein; C086566:glycitein; D019833:Genistein; D017430:Prostate-Specific Antigen