Urinary isoflavone excretion as a compliance measure in a soy intervention among young girls: a pilot study.
OBJECTIVE
To investigate the compliance of young girls with a soy intervention.


METHODS
An 8-week dietary intervention and urine sample collection.


METHODS
Free-living girls.


METHODS
A convenience sample of 8- to 14-y-old girls (20 started and 17 finished the study) recruited through flyers distributed to staff members and previous study participants.


METHODS
The girls consumed one daily serving of soymilk, soy nuts, or tofu, completed 3-day food records, kept daily soy intake logs, and collected weekly urine samples.


METHODS
Compliance with the intervention was evaluated by daily soy intake logs, 3-day food records analyzed by the center's Food Composition and Food Groups Servings Databases, and weekly urinary isoflavone excretion using high-pressure liquid chromatography. The statistical analysis included paired t-tests, analysis of variance, and Spearman's rank-order correlation coefficients.


RESULTS
Daily soy intake logs indicated a mean intake of 6.28 servings out of a maximum of 7.0 servings per week. The food records revealed a six-fold increase in isoflavone intake during the study period (P<0.01) which was confirmed by an increase in urinary isoflavone excretion of similar magnitude (23.3-142.1 nmol/mg creatinine, P=0.02).


CONCLUSIONS
This study demonstrated the ability of young girls to consume one daily soy serving and the usefulness of urinary isoflavones as a primary compliance measure. The high urinary isoflavone excretion levels detected in girls as compared to adult women suggest less intestinal degradation and/or greater absorption of isoflavones in nonadult populations. This finding requires further investigations into the pharmacokinetics of isoflavones.
Maskarinec
G
G
Cancer Research Center of Hawaii, Honolulu, HI 96813, USA. Gertraud@crch.hawaii.edu
Oshiro
C
C
Morimoto
Y
Y
Hebshi
S
S
Novotny
R
R
Franke
A A
AA
D000293:Adolescent; D000704:Analysis of Variance; D015415:Biomarkers / Q000652:urine; D002648:Child; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D015930:Diet Records; D005260:Female; D006801:Humans; D007408:Intestinal Absorption; D007529:Isoflavones / Q000493:pharmacokinetics* / Q000652:urine*; D010349:Patient Compliance; D010865:Pilot Projects; D045730:Soy Foods
D015415:Biomarkers; D007529:Isoflavones