The only things that truly reduce H/H are dose reduction and a good bit of cardio. I believe steady state cardio is the better choice, maybe 30mins 5 times a week. Things like fish oil, nattokinase, baby aspirin do nothing to lower H/H in the vast majority of people. They simply help to keep you from clotting. I've over donated in the past and crashed the fuck out of my iron and ferritin. I now only donate if I'm symptomatic and/or the number starts looking a bit scary. If my hematocrit hits around 57-58, I tend to donate.