From anabolicmen.com:
"Cruciferous Vegetables like broccoli, kale, brussel sprouts, cauliflower, maca, and so on are filled with some very favorable compounds to decrease your estrogen levels.
1. They’re rich in zinc which is a mineral known to boost testosterone. Zinc also stops the aromatase enzyme from doing its damage on your testosterone levels, so that your T doesn’t convert so easily to estrogen anymore.
2. They’re rich in a compound called Indole-3-Carbinol (I3C) which converts into 3,3-Diindolylmethane (DIM) in your stomach. DIM is known best for its ability to regulate estrogen, which means that it effectively flushes out estrogenic compounds and xeno-estrogens from your body.
Many people like to eat their cruciferous vegetables steamed. However, I believe that when you expose those veggies to too much heat, they’ll lose some of the beneficial nutrients."
Obviously anabolicmen.com is not a 10 year, double-blind, clinical research study with a population of 100,000. But I have seen numerous references to cruciferous vegetables helping to control estrogen and aid in reducing gyno. I'm a firm believer in exploring every avenue and these vegetables are good for you even if they don't help with the gyno.
Cheers