Phytoestrogens are estrogen-like compounds. They have the same effect as taking estrogen, so they can disrupt hormones. They are found in other foods too, especially seeds–soy is the most common example, and flax is a close second. Some people seem to ingest significant amounts with no issues, but others are more sensitive to them. I was eating a lot of flax, and experienced really heavy bleeding–so severe it caused me to have anemia. Males can have more feminine characteristics like “man boobs” if they ingest a lot (I’m not sure how much is a lot–I think it might vary person to person).
It’s not my intention to put a damper on your enjoyment of hemp, just to caution that you should use moderation because it does have REAL physiological effects. I saw a recipe that suggested hemp in place of couscous as a sort of side pilaf with a meal, and I would say that a 1/2 cup or so serving is probably too much, but may be OK for most people if done infrequently.
I like almonds and almond flour, so sometimes it seems like I’m ingesting a lot of almond flour–it shows up in multiple recipes I use throughout a week (note: I’m really trying to reduce the amount of almond flour because there are negative consequences to high levels of Omega 6, too). If I ingested that much hemp, that would be very bad for me. But I had no idea that flax was going to cause problems for me until I experienced those problems (and had to do a lot of googling to identify the source of those problems!) . I’m just trying to raise awareness. Enjoy hemp, but don’t overdo.