from my research, it seems that vitamin B3 essentially protects our cells from attack, however once this wears of, our cells will once again be attacked, and thus you may become reliant on high levels of niacin. Now if dairy was the cause of your body to attack proteins, which is elevated upon ejaculation (maybe because of protein from semen somehow entering the blood stream) I would strongly reccomend staying away from dairy which obviously helps the body distinguish between protein in the blood stream which shouldnt be there (diary) and unharmfull protein (from semen). Dr. John mcdougall explains that when the cells of our gut become weak or damaged, dairy proteins exit from the gut into the blood, the body recognizes these as viruses and the lymphocytes create antibodies to kill these proteins. Now, these antibodies are then circulating the blood stream and what causes autoimmune disorders is when these antibodies start atacking anything that is similar to the protein they were created to atack (in this case dairy protein), the targets include many of the cells within our body. So possibly, when protein from semen somehow enters the blood stream, the antibodies begin to attack these also. This process increases the creation of antibodies and thus the damage to our body. If this theory is correct, I would highly reccomend you stop your intake of dairy products in order to train your body not to attack similar cells and proteins.
Once again if you would like a copy of the book or a link to some of the studies i have been reading up on, just let me know.