I've had PV for three years and do phlebotomies generally about once a month. In discussion with my oncologist/hematologist we talked about what I might do to slow the production of blood down. One of the areas we talked about was the potential influence of one's diet. My doctor said that I should maintain my overall health to the best of my abilities and we also talked about the possibility of a reduced iron intake, since that is one of the fundamental building blocks of blood. I needed to drop some weight so I started a diet that put me into nutritional ketosis. That worked wonders for shedding pounds but one thing that I noticed was that the duration between my phlebotomies increased — I was getting a phlebotomy once every three months instead of once per month while I was in nutritional ketosis. There hasn't been any studies on this to my knowledge, but it was a connection that I made based on my own personal experience. Your mileage may very. I would encourage you to talk to your doctor and explore what options are available to you. I didn't feel very well when my hematocrit got too high — my doctor has set the threshold at 45% for me (greater than 45% = time to get a phlebotomy). Maintaining at 45% has kept me feeling pretty good and I'm still able to be very active (I work as a soccer referee).