In response to Paleomedicina's statement
False, on every level. Histamine intolerance is, in fact, an enzyme deficiency in which the body does not produce enough DAO (diamine oxidase) and HNMT (histamine-N-methyl-transferase) to break histamines down like in someone without intolerance. Histamines are a normal immune function of the body and it causes a cascade reaction where the immune system fights off foreign invaters and protects you, but if you are deficient in said enzymes, it becomes chronic and is a double-edged sword.
One correct point: leaky gut can and does cause enzyme imbalance and histamine reaction, and thus assisting your gut in healing can heal some people of histamine intolerance, but not all.
One major factor is gut biome, as some bacteria produce these enzymes, so getting a healthy gut biome is beneficial to this process. I, myself, eat dirt, especially that black mud near rivers. It is filled with beneficial compounds and a full set of healthy microbes that benefit anyone no matter what their lifestyle is. They even sell this stuff in capsules as a probiotic supplement... Altering the biome can effectively "cure" people of this disorder, but like I said above, those with a severe deficiency find that avoidance is the only answer.
Citrus contributes to histamine problems, which means even as a medicine, it should never be used by one suffering this problem.
Chocking it all up to leaky gut is not correct. It is demeaning to the people who have this condition, and claiming they are imagining having a problem at all. They do have an actual disorder, and it is actually studied, and it has been found to be an actual occurrence which afflicts a small number of individuals who end up going fresh meat Carnivore as it alleviates the symptoms.
I know from personal experience how a deficiency in even one enzyme can make life a living Hell. I suffer from porphyria, with traits around hereditary coproporphyria, in which the enzyme coproporphyrinogen oxidase is deficient. I am, consequently, violently sensitive to sunlight and bright lights, and they cause severe burns, rashes, blisters, seizures, nerve pain, spasms, intestinal ruptures, and other symptoms. I am also deficient in disaccharidases, which is the enzyme type that is essential to breaking down carbohydrate, and thus I am severely carbohydrate intolerant and they make me extremely ill in very low amounts; this is linked to autism, which I have, and autistic people thrive on Ketogenic and Carnivore because those lifestyles remove the substance causing their degenerating brain and gut.
Smolinska, S., Jutel, M., Crameri, R., & O'Mahony, L. (2014). Histamine and gut mucosal immune regulation. Allergy, 69(3), 273-281.
Maintz, L., & Novak, N. (2007). Histamine and histamine intolerance. The American journal of clinical nutrition, 85(5), 1185-1196.
Johnston, C. S. (1996). The antihistamine action of ascorbic acid. In Subcellular Biochemistry (pp. 189-213). Springer US.
Martner-Hewes, P. M., Hunt, I. F., Murphy, N. J., Swendseid, M. E., & Settlage, R. H. (1986). Vitamin B-6 nutriture and plasma diamine oxidase activity in pregnant Hispanic teenagers. The American journal of clinical nutrition, 44(6), 907-913.
Rosell-Camps, A., Zibetti, S., Pérez-Esteban, G., Vila-Vidal, M., Ferrés-Ramis, L., & García-Teresa-García, E. (2013). Histamine intolerance as a cause of chronic digestive complaints in pediatric patients. Revista espanola de enfermedades digestivas: organo oficial de la Sociedad Espanola de Patologia Digestiva, 105(4), 201-207.
Kohn, J. B. (2014). Is There a Diet for Histamine Intolerance?. Journal of the Academy of Nutrition and Dietetics, 114(11), 1860.
Ji, Y., Sakata, Y., Li, X., Zhang, C., Yang, Q., Xu, M., ... & Tso, P. (2013). Lymphatic diamine oxidase secretion stimulated by fat absorption is linked with histamine release. American Journal of Physiology-Gastrointestinal and Liver Physiology, 304(8), G732-G740.
Shakir, K. M., Margolis, S., & Baylin, S. B. (1977). Localization of histaminase (diamine oxidase) in rat small intestinal mucosa: site of release by heparin. Biochemical pharmacology, 26(24), 2343-2347.
Luk, G. D., Bayless, T. M., & Baylin, S. B. (1980). Diamine oxidase (histaminase). A circulating marker for rat intestinal mucosal maturation and integrity. Journal of Clinical Investigation, 66(1), 66.
Hamada, Y., Shinohara, Y., Yano, M., Yamamoto, M., Yoshio, M., Satake, K., ... & Usami, M. (2013). Effect of the menstrual cycle on serum diamine oxidase levels in healthy women. Clinical biochemistry, 46(1), 99-102.
Fukudome, I., Kobayashi, M., Dabanaka, K., Maeda, H., Okamoto, K., Okabayashi, T., ... & Hanazaki, K. (2013). Diamine oxidase as a marker of intestinal mucosal injury and the effect of soluble dietary fiber on gastrointestinal tract toxicity after intravenous 5-fluorouracil treatment in rats. Medical molecular morphology, 1-8.
Ferstl, R., Frei, R., Schiavi, E., Konieczna, P., Barcik, W., Ziegler, M., ... & O'Mahony, L. (2014). Histamine receptor 2 is a key influence in immune responses to intestinal histamine-secreting microbes. Journal of Allergy and Clinical Immunology, 134(3), 744-746.