Variations in Phytoestrogen Content Between Different Mill Dates of the Same Diet Products Significant Differences in the Time of Vaginal Opening in CD-1 Mice and F344 Rats but Not in CD Sprague-Dawley Rats

• Published in: Environmental health perspectives Vol. 115; no. 12; p. 1717
• Main Authors: Thigpen, Julius E, Setchell, Kenneth DR, Padilla-Banks, Elizabeth, Haseman, Joseph K, Saunders, Hannah E, Caviness, Gordon F, Kissling, Grace E
• Format: Journal Article
• Language: English
• Published: 01.12.2007
• ISSN: 0091-6765

Importance of species and diet differences in measuring the estrogenic activity of endocrine disrupting compounds (EDCs) is evaluated. It is found that CD-mouse and the F344 rat are considerably more sensitive to dietary phytoestrogens than the S-D rat. The same diet milled on different data may have significantly different phytoestrogen content, which will cause marked differences in the time of vaginal opening (VO) in CD-1 mice and F344 rats, but less so in S-D rats. It is suggested that variations in the phytoestrogen content of rodent diets can be overcome using soy- and alfalfa-free diets and by eliminating other known sources of estrogens. It is concluded that a standardized open-formula phytoestrogen-deficient diet coupled with a more estrogen sensitive rodent model will be most appropriate to use in bioassays for evaluating the estrogenic activity of EDCs.