I think estrogen plays a much larger role in hair-loss than DHT. One of the prostaglandins made from arachidonic-acid (omega-6) called prostaglandin-E2 induces aromatase-activity. Estrogen increases the catagen stage of hair growth in both sexes.
On the subject of diet, do you advise against white button mushrooms, as part of a vegan diet? I'm trying to work against hair loss in the best ways I can. Any other dietary input would of course be welcome.