Q:

What increases Histamine in the body?

What increases histamine in the human body, and are there oral forms of intake to stimulate this increase?

A:

Yep. Try spoiled fish. 

Histamine Poisoning (Scombroid Fish Poisoning): An Allergy-Like Intoxication
Histamine poisoning results from the consumption of foods, typically
  certain types of fish and cheeses, that contain unusually high levels
  of histamine. Spoiled fish of the families, Scombridae and
  Scomberesocidae (e.g. tuna, mackerel, bonito), are commonly implicated
  in incidents of histamine poisoning, which leads to the common usage
  of the term, “scombroid fish poisoning”, to describe this illness.
  However, certain non-scombroid fish, most notably mahi-mahi, bluefish,
  and sardines, when spoiled are also commonly implicated in histamine
  poisoning. Also, on rare occasions, cheeses especially Swiss cheese,
  can be implicated in histamine poisoning.
The symptoms of histamine poisoning generally resemble the symptoms
  encountered with IgE-mediated food allergies. The symptoms include
  nausea, vomiting, diarrhea, an oral burning sensation or peppery
  taste, hives, itching, red rash, and hypotension. The onset of the
  symptoms usually occurs within a few minutes after ingestion of the
  implicated food, and the duration of symptoms ranges from a few hours
  to 24 h. Antihistamines can be used effectively to treat this
  intoxication.
Histamine is formed in foods by certain bacteria that are able to
  decarboxylate the amino acid, histidine. However, foods containing
  unusually high levels of histamine may not appear to be outwardly
  spoiled. Foods with histamine concentrations exceeding 50 mg per 100 g
  of food are generally considered to be hazardous. Histamine formation
  in fish can be prevented by proper handling and refrigerated storage
  while the control of histamine formation in cheese seems dependent on
  insuring that histamine-producing bacteria are not present in
  significant numbers in the raw milk.

Lehane, L. & Olley, J. (2000). Histamine fish poisoning revisited. International Journal of Food Microbiology, 58, 1-37.

