A controlled 2-mo dietary fat reduction and soy food supplementation study in postmenopausal women.
BACKGROUND
Low intake of dietary fat and high intake of soy foods have been suggested to partly explain the lower breast cancer rates in Asia, perhaps because of lower endogenous estrogens.


OBJECTIVE
The objective was to assess the hormonal and nonhormonal effects of diets resembling an Asian diet in terms of total fat and soy food contents.


METHODS
Fifty-seven postmenopausal women participated in a randomized, controlled, dietary intervention study. The subjects consumed a very-low-fat diet (VLFD; 11% of energy as fat), a Step I diet (25% of energy as fat) supplemented with soy food (SFD; 50 mg isoflavones/d), or a control Step I diet (CD; 27% of energy as fat) with no soy food. All diets were prepared at the General Clinical Research Center of the University of Southern California. Serum hormones and other markers were measured at baseline and every 2 wk during the 8 wk of intervention.


RESULTS
There were no significant differences in total estradiol and sex hormone binding globulin at the completion of the intervention between women in the SFD and VLFD groups and those in the CD group. Serum insulin decreased significantly in the SFD group, and leptin decreased significantly in the SFD and VLFD groups; however, these changes did not differ significantly from the changes in the CD group.


CONCLUSIONS
This study does not provide evidence that ingestion of soy food or a VLFD significantly reduces estrogen concentrations in postmenopausal women. However, short-term changes in diet may have significant and beneficial effects on blood insulin and leptin concentrations.
Wu
Anna H
AH
Department of Preventive Medicine, University of Southern California/Norris Comprehensive Cancer Center, Keck School of Medicine, Los Angeles, CA 90089-9175, USA. annawu@usc.edu
Stanczyk
Frank Z
FZ
Martinez
Carmen
C
Tseng
Chiu-Chen
CC
Hendrich
Suzanne
S
Murphy
Patricia
P
Chaikittisilpa
Sukanya
S
Stram
Daniel O
DO
Pike
Malcolm C
MC
D004041:Dietary Fats / Q000008:administration & dosage* / Q000032:analysis / Q000494:pharmacology; D004967:Estrogens / Q000097:blood*; D005260:Female; D005504:Food Analysis; D006801:Humans; D007328:Insulin / Q000097:blood; D007529:Isoflavones / Q000032:analysis / Q000652:urine; D020738:Leptin / Q000097:blood; D008875:Middle Aged; D017698:Postmenopause / Q000097:blood*; D030262:Soybean Proteins / Q000008:administration & dosage* / Q000032:analysis / Q000494:pharmacology
D004041:Dietary Fats; D004967:Estrogens; D007328:Insulin; D007529:Isoflavones; D020738:Leptin; D030262:Soybean Proteins