Histamine Intolerance, from what I know about it, has nothing to do with histadelia or mast cell activation, but is a response to dietary histamines. Here is the seminal article:
http://ajcn.nutrition.org/content/85/5/1185.long
My findings regarding the different food lists and supplements online - what is out there is all over the place. I have a list of foods that works for me (PM me and I'll send it). It was a pretty good list before I found the above article and started researching, but when I challenged the differences - foods that I thought I couldn't eat but were low histamine and vice versa - they were right and I was wrong. The Low Histamine Chef cookbook is full of recipes that have enough histamine in them that the whole cookbook is useless to me.
Big deals other than food: Avoid N-acetyl cysteine (NAC). Avoid contrast media when having imaging done (or elect pretreatment options such as diphenhydramine and prednisone). It's a short list.
Food big deals: ANYTHING aged, cultured, or fermented. Any animal protein that has been cooked and then refrigerated overnight (my limit is about 12 hours refrigeration). Tomatoes, red or green peppers, eggplant, pumpkin, chayote squash. Cinnamon, cloves, curry, turmeric.
Also deals, although not as big at least for me: berries and stone fruits. Some people have trouble with citrus, although that seems to be more in the citrus causing the release of histamines from your own cells (more along the MCAS lines) than the dietary histamine intolerance.
What really helps me: a 72-hour water-only fast is the biggest help. 4R gut rebuilding that I did before the first fast might have been necessary. DAOsin or Histame (diamine oxidase, the enzyme to break down histamine in the gut) helps if I'm already not reacting badly but just reacting a little -when I was bad there was no noticeable improvement from using it. Note that DHist has NAC in it - which is contraindicated for histamine intolerance.
Grateful that you have hope of slaying the dragon now that it's been named!
Critterina