Histaquel from Researched Nutritionals combines seven flavonoids to support healthy mast cell function by promoting a healthy amount of histamine release, along with herbs shown to block histamine from attaching to receptors via competitive inhibition. Comprehensive Mast Cell Support Allergies may develop as a result of many environmental conditions. When exposed to an allergen, the human body produces a natural mast cell activation response. This mast cell activation causes a release of histamine which when released, binds to histamine receptors causing common allergy symptoms.