Research Library
Two-week dietary soy supplementation has an estrogenic effect on normal premenopausal breast.
Authors: Hargreaves DF; Potten CS; Harding C; Shaw LE Morton MS; Roberts SA; Howell A; Bundred NJ
Source: J Clin Endocrinol Metab 1999 Nov;84(11):4017-24
An association has been reported between consumption of a high soy
diet and a low incidence of breast cancer within populations of
Southeast Asia. Phytoestrogens present in soy act as partial estrogen
agonists or antagonists and can inhibit breast cancer cell
proliferation in vitro. The effect of 14-day dietary soy
supplementation with 60 g (45 mg isoflavones) on the normal breast of
84 premenopausal patients was determined. Serum concentrations of the
isoflavanoids, genistein, daidzein, and equol, were raised in
patients after soy supplementation (P < or = 0.025). Nipple
aspirate (NA) levels of genistein and daidzein were higher than
paired serum levels, both before (P < 0.001 and P = 0.001,
respectively) and after soy supplementation (P < 0.001 and P =
0.049, respectively); however, there was no significant increase in
NA isoflavone levels in response to soy. NA levels of apolipoprotein
D were significantly lowered and pS2 levels raised in response to soy
supplementation (P < or = 0.002), indicative of an estrogenic
stimulus. No effect of soy supplementation on breast epithelial cell
proliferation, estrogen and progesterone receptor status, apoptosis,
mitosis, or Bcl-2 expression was detected. In conclusion, short term
dietary soy has a weak estrogenic response on the breast, as measured
by nipple aspirate apolipoprotein D and pS2 expression. No
antiestrogenic effect of soy on the breast was detected.