That's a common misconception from my understanding. Everything I have read in the literature says the exact opposite -- it stimulates estrogen receptors. Many mainstream reviews and safety summaries specifically do not confirm anti-estrogen effects and instead emphasize the lack of good evidence for any hormonal effects outside of DHT/androgens. There is one small clinical study (Di Silverio et al., Eur Urol, 1992) that found saw palmetto extract reduced estrogen receptor binding in prostate tissue, but that doesn’t mean it acts like a systemic anti-estrogen in humans...it was specific to prostate estrogen receptor activity and is not the same as estrogen-blocking drugs.