What are the active ingredients is Histamine Block derived from? Ceylon Keeslar October 31, 2019 17:15 Updated Follow Diamine oxidase is derived from porcine (pig) protein concentrate. Vitamin C is from non-GMO corn. Related articles What are the possible interactions or side effects of using Histamine Block? Does this product contain gluten, soy, or grains? Comments 0 comments Article is closed for comments.