In a study published in the American Journal of Clinical Nutrition, when postmenopausal women ate a daily muffin containing either 25 grams (a little less than 1 ounce) of soy protein, 25 grams of ground flaxseed, or a placebo muffin containing neither for 16 weeks, the estrogen metabolism of those eating flaxseed, but not soy or placebo, was altered in several important protective ways:
* Levels of 2-hydroxyestrone, a less biologically active estrogen metabolite thought to be protective against breast cancer, increased significantly.
* The ratio of 2-hydroxyestrone (the protective estrogen metabolite) to 16alpha-hydroxyestrone (an estrogen metabolite thought to promote cancer) increased.
* Blood levels of the estrogen fractions (estradiol, estrone, and estrone sulfate) did not change significantly-which is important since estradiol is involved in maintaining bone mass.
So what does this mean in plain English? Eating about an ounce of ground flaxseed each day will affect the way estrogen is handled in postmenopausal women in such a way that offers protection against breast cancer but will not interfere with estrogen's role in normal bone maintenance.
