Three measures show high compliance in a soy intervention among premenopausal women.
OBJECTIVE
To evaluate adherence to a soy-based diet among premenopausal women.


METHODS
First year of a 2-year, randomized dietary intervention.


METHODS
220 healthy premenopausal women who reported low baseline soy intake.


METHODS
5 counseling visits, 7 follow-up phone calls, and 12 group meetings. Main outcome measures Self-reported soy intake logs; food frequency questionnaires; repeated, randomly timed 24-hour recalls; and analysis of urinary isoflavone excretion by high-pressure liquid chromatography. Statistical analyses Frequency distributions, means, t tests, and mixed effects models.


RESULTS
At baseline, the 2 groups did not differ in dietary soy intake (P=.51) or urinary isoflavone excretion (P=.16). According to the 24-hour recalls and the food frequency questionnaires, the intervention group's estimated isoflavone intake increased more than 10 times compared with baseline and with the control group (P<.0001). During follow-up, urinary isoflavone excretion results showed no change in the control group, but a 6-fold increase for intervention subjects (P<.0001). Intake logs showed a strong preference for soymilk and tofu over the other foods and indicated that intervention participants consumed at least 12 servings of soy foods per week during 84 out of 100 follow-up contacts.


CONCLUSIONS
These data indicate a high level of compliance with the study regimen, which we attribute to the following strategies: repeated contact with the study subjects, personal relationships with the dietitians, wide choice of soy foods, easy access to soy foods at no cost, and recipes that allowed substitution of previously eaten foods with soy products.
Maskarinec
Gertraud
G
Cancer Research Center of Hawaii, Honolulu, HI 96813, USA. gertraud@crch.hawaii.edu
Robbins
Casey
C
Riola
Bernard
B
Kane-Sample
Lauren
L
Franke
Adrian A
AA
Murphy
Suzanne
S
D000328:Adult; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004032:Diet; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007529:Isoflavones / Q000008:administration & dosage* / Q000652:urine*; D008137:Longitudinal Studies; D011939:Mental Recall; D008875:Middle Aged; D010349:Patient Compliance; D017697:Premenopause; D013025:Glycine max / Q000378:metabolism; D011795:Surveys and Questionnaires
D007529:Isoflavones