I'm lamenting over this on my blog if you want to read more. Or try googling "saw palmetto estrogen blocker" and "is saw palmetto estrogenic" and you will see that no one really knows what saw palmetto does to estrogen.
I am leaning towards believing that saw palmetto increases estrogen. Read this article: http://www.drnandunne.com/?p=1808
And if you don't feel like reading the whole thing, check out this quote: It is important to understand that saw palmetto (and potentially any herb that lowers blood levels of testosterone) will cause your androgens to be converted to estrogens. This increase in estrogens can further complicate your PCOS, and risk your long term health. When you slow down the conversion of testosterone to DHT, you leave more testosterone to be converted to estrone. In other words, you may be trading one problem in this picture for another.
That sums it up for me - Saw Palmetto helped but it also caused problems. It immediately reduced oil and cleared my back and my skin looked great for awhile. But it's also doing something to cause crazy post menstrual flare ups and emotional issues. And I was taking only one 160 mg per day. So this is powerful stuff. My advice is to start slow and keep a log of what's going on with your body.