@Sherlock, It's funny, I knew when I was taking niacin last month that it causes mast cell degranulation, and I was doing it to release histamines and avoid histamine build up, but all of a sudden it had a new meaning. After a while I realized it was making my sore throat so much worse and quit taking it. I realize calcium is part of the cause of mast cell degranulation, and then there's usually something else involved, so I have to find out what else is involved when taking niacin. Strange. I'll google that with the PGD2 that you mention.