Format

Send to

Choose Destination
See comment in PubMed Commons below
Biomarkers. 2010 Mar;15(2):135-9. doi: 10.3109/13547500903335927.

Reliability of serum and urinary isoflavone estimates.

Author information

1
Department of Epidemiology and Biostatistics, School of Public Health, Loma Linda University, Loma Linda, CA 92350, USA. gfraser@llu.edu

Abstract

Sporadic intake and short half-lives of serum or urinary biomarkers may make serum and urinary isoflavones quite unreliable indicators of longer-term dietary soy intake. In 26 participants in the Adventist Health Study-2 (AHS-2) we obtained two measures of fasting morning serum isoflavones, 1-2 years apart. In another 76 subjects we obtained an overnight urine sample and six 24-h dietary recalls over a period encompassing the time of the urine sample. Intraclass correlations (ICC) values for serum isoflavones were 0.11 (log(daidzein)) and 0.28 (log(genistein)). Assuming that the correlation (true dietary intake, true urinary excretion) <0.90, it is shown that this implies an ICC for urinary estimates that exceeds 0.56. As expected, the previous day's soy intake, and its timing, influenced the next morning's serum levels. These results suggest that fasting morning serum isoflavone estimates will provide a poor index of long-term soy intake, but that overnight urinary estimates perform much better.

PMID:
19863459
PMCID:
PMC2824772
DOI:
10.3109/13547500903335927
[Indexed for MEDLINE]
Free PMC Article
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for Taylor & Francis Icon for PubMed Central
    Loading ...
    Support Center