I just read a post by Critterina today that lead me to a very interesting article with a very interesting chart. Here is the article Histamine. I have been trying to figure out how to get rid of histamine in my son, and the chart showed me something I didn't realize before. The pathways to getting rid of histamine are full of feedback loops that can block your ability to get rid of histamine. It isn't enough to look at the first level down from histamine - you have to look at the next level to see that you are supporting that level, too. I think it is easiest to see it in the chart so here is the chart with my notes in red. I got the information about aldehyde dehydrogenase needing niacin from the Wikipedia page http://en.wikipedia.org/wiki/Aldehyde_dehydrogenase I think that niacin, or niacinamide which is better as a supplement, might be the missing ingredient for some people who are trying to get rid of excess histamine. I was giving niacinamide 1 gm three times a day to my son and he was gradually getting better, then I didn't give the evening and morning dose of niacinamide and he was much worse that day even though I was still giving the other supporting supplements. I can't be 100% sure that the niacin was the cause of that because I can think of another plausible explanation, but I have started him back on it and plan to continue and see how it goes. If you see some cofactors that are missing or have any suggestions about the chart please let me know.