Premium
Dose‐dependent effect of soy protein intake on isoflavone and metabolite urinary excretion
Author(s) -
Baer David J.,
Huth Peter J.,
Martini Margaret C.,
Lampe Johanna W.
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.5.a371-c
Subject(s) - daidzein , equol , genistein , excretion , isoflavones , enterolactone , chemistry , urine , soy protein , phytoestrogens , metabolite , endocrinology , medicine , food science , biochemistry , estrogen
Consumption of soy protein has been found to reduce risk for cardiovascular disease and some cancers. In order to evaluate the dose effect of soy protein consumption on excretion of isoflavones and metabolites, a study of adult subjects (n=31) was conducted. Soy protein isolate (SPI) in processed food products was fed as part of an isoenergetic, controlled diet (20 en% prot., 37 en% fat) in a crossover design. Zero, 20, 30, or 40 g protein/d from SPI was substituted for dairy protein. After 5 wks, all urine voided during 3 consecutive 24‐hr periods was collected and analyzed for genistein, daidzein, equol, O‐desmethylangolensin (ODMA), enterolactone, and enterodiol by isotope‐dilution GC‐MS. Total isoflavone excretion was 1.10, 1.92, 2.58, 3.36 micromol/d (1.72 micromol/d SE), respectively for the 4 treatments. Genistein, daidzein, and ODMA excretion was significantly affected by the amount consumed in a linear manner (p<0.05). In equol producers (74% of subjects), excretion was significantly affected by amount consumed (p<0.001) but in a nonlinear manner (p>0.2). Excretion of enterodiol but not enterolactone was linearly related to dose consumed. Thus, while consuming SPI, the ratio of excreted isoflavones is proportionate (approx. 50% genistein, 20% daidzein, 20% ODMA,10% equol) to the amount consumed albeit the absolute amount excreted increases with increasing dose. Supported by USDA & Kraft Foods, Inc.