Mast Cell Activation Syndrome would be the main one. Mast cells are an integral part of the intestinal epithelial barrier. When they become over-sensitive, even

Mast Cell Activation Syndrome would be the main one. Mast cells are an integral part of the intestinal epithelial barrier. When they become over-sensitive, even small amounts of dietary histamine (present in a large number of foods) can trigger GI and systemic symptoms. H2 blockers have shown some efficacy, as well as DAO supplements (which break down dietary histamine).