Ok, thanks for the relpy. So it's not beta sitosterol that causes the increase in estrogen levels. Does that mean that BS doesn't cause an increase when taken on its own?
The plant steroids in saw palmetto act on progesterone receptors, that causes a reduction in estrogen levels. According to the results of a large international trial published in the "Journal of Clinical Oncology" in April 2011, estrogen and progesterone receptor status is a predictive marker of early breast cancer and post-treatment relapse.
As you get older your hormone levels decrease, and your fat cells in your body increases. This can cause higher levels of aromatase, an enzyme that converts testosterone to estrogen. The treatment of benign prostatic hyperplasia in men and breast cancer in post-menopausal women is to use a class of drugs called aromatase inhibitors. According to Jaroslav Drsata, a scientist in the Czech Republic, the enzyme-blocking properties of saw palmetto may include aromatase.