I was looking around for studies, specifically randomized control trials (RCTs), on tea’s ability to inhibit the enzyme 5-alpha-reductase. Pumpkin seeds can inhibit 5-alpha-reductase. It’s thought that this inhibition is responsible for the seeds’ positive effect on urination in men with enlarged prostate.*
* Testosterone gets converted to dihydrotestosterone (DHT) via 5-alpha-reductase. DHT is the primary contributing factor in male pattern baldness, and plays a role in the development of benign prostatic hyperplasia (BPH), as well as prostate cancer, by enlarging the prostate gland.
I haven’t found any RCTs yet, but I did find this:
An Update On Plant Derived Anti-Androgens, International Journal of Endocrinology and Metabolism, April 2012
4.10. Green Tea (Camellia sinensis)
In addition to supporting the cardiovascular system and somewhat reducing the risk of cancer and type 2 diabetes (8), green tea may also have an important anti-androgen effect because it contains epigallocatechins, which inhibit the 5-alpha-reductase conversion of normal testosterone into DHT. As previously noted, this anti-androgen mechanism may help to reduce the risk of BPH, acne, and baldness. As yet, no randomized controlled trials of green tea for these androgen dependent conditions have been conducted.
So, green tea can inhibit 5-alpha-reductase, and may also (in conjunction with pumpkin seeds and flax seeds) reduce urination difficulties associated with an enlarged prostate, as well as stimulate hair growth. But, as of 2012 at least, no RCTs.
This review included a list of plants thought to have anti-androgen effects. It’s nice to see. It helps dissipate the fog of magic foods: