[jinder]

Some people really do have mast cell issues, but everyone and their dog thinks they have MCAS these days and it's questionable in my opinion. Often a diagnosis will be based on whether any of the MCAS-drugs work (rather than testing which is very problematic for MCAS). But as you see in the linked paper famotidine was effective in mice genetically engineered without mast cells, so at least in that instance it's not a mast cell issue.

The tricky thing with increasing butyrate production is that everyone's gut dysbiosis is different - and therefore, a prebiotic that works for one person may make someone else's condition worse. For example, I have big blooms in my Prevotella Copri population which would consume Inulin and make my butyrate production worse - but in people without a Prevotella Copri overgrowth, Inulin would improve their butyrate production.

I would look into 16S microbiome testing (I use Biomesight) and use that as a guide, as well as slowly trialing interventions and monitoring symptoms. None of this is perfect and you kinda have to be on the bleeding edge of science/alternative medicine to figure things out.