Abstract
Objective: To study dietary intake and serum concentrations of isoflavones in order to provide relative validation of isoflavone intake estimates from the Scottish Collaborative Group - Food-Frequency Questionnaire (SCG-FFQ).
Design: Validation study.
Setting: Southern Scotland.
Method: Dietary intake of isoflavones was estimated using the semiquantitative SCG-FFQ and rank correlation and Kappa statistics were used for the relative validation of intakes against serum isoflavone concentrations in 203 male participants who were population controls in a case - control study of diet and prostate cancer.
Results: The median intake of isoflavones ( daidzein and genistein) was 1.0 mg/day (I-QR 0.6 - 1.8). The median serum concentration of genistein was 33.79 nmol/ l ( I-QR 14.12 - 64.93), nearly twice that of daidzein ( 18.00 nmol/ l, I- QR 8.26 - 29.45). Equol was detected in 49% of subjects; in these subjects the median was 0.67 nmol/ l ( I- QR 0.34 - 1.51). Isoflavone intake was significantly correlated with serum concentrations of daidzein (rho = 0.24, P = 0.001), genistein (rho = 0.26, P<0.001) and total isoflavonoids ( sum of daidzein, genistein and equol) (rho = 0.27, P<0.001). Whereas values for weighted Kappa ranged from 0.16 ( P = 0.002) for daidzein and equol combined to 0.22 (P<0.001) for genistein.
Conclusions: These results demonstrate the suitability of the SCG-FFQ to rank usual isoflavone intakes in older Scottish men, a population observed to have low consumption of soy foods.
Original language | English |
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Pages (from-to) | 129-135 |
Number of pages | 7 |
Journal | European Journal of Clinical Nutrition |
Volume | 60 |
DOIs | |
Publication status | Published - Jan 2006 |
Keywords
- isoflavones
- diet
- validation study
- daidzein
- genistein
- biomarker
- URINARY ISOFLAVONE EXCRETION
- DIETARY SOY INTAKE
- PLASMA-CONCENTRATIONS
- UNITED-STATES
- PHYTOESTROGEN EXPOSURE
- GUT MICROFLORA
- JAPANESE MEN
- WOMEN
- POPULATION
- CANCER