Tuesday, May 31, 2011

Food Allergies Might Not Be An Allergy

Allergies from foods are multifactorial in causes. A single mechanism by which patients react to foods is at present unclear.

Historically, diets are found to be useful in migraine headaches, irritable bowel syndrome (IBS), Crohn’s disease, eczema, hyperactivity, and rheumatoid arthritis. Because there are occasionally no findings in the IgE and RAST (radioallergoabsorbent testing), such results lead some investigators to conclude that food allergy symptoms are merely neurotic symptoms.

Inhibitors of detoxification might be coming from gut flora. We know that encephalopathy in cirrhotic patients develops after a meal where they cannot metabolize the amino compounds produced by gut flora. The gut produces a wide array of substances which cause reactions with all organs in the body. Colonic microflora produce a wide variety of chemicals, in susceptible individuals with reduced hepatic enzymes, they pass into systemic circulation to produce symptoms at distant parts. It is well known that IBS can come on after surgery, radiation, gastroenteritis, and the use of antibiotics, all of which may change the bowel flora. Elevated facultative anaerobes rises after a food challenge in patients with IBS. Food allergy may not be an immunologic disease but a disorder of bacterial fermentation and enzyme deficiency. Enteroadherent E. coli are present in the stool in a high percentage of patients with a variety of food related autoimmune problems such a s Crohn’s disease. Abnormal bacteria are also found in patients with RA, ankylosing spondelytis. HLA B27 is synthesized by the fecal flora and associated with facultative anaerobes, klebsiella and proteus.

And foods have their own reactions that they generate outside of allergy models. As an example tyramine in chocolate causes bouts of headaches in susceptible people because of genetic inability to detoxify this vasoactive amine before it goes out into systemic circulation. This is probably related to genetic predisposition, in patients with migraines, they have a low level of monoamine oxidase (MAO) and phenolsulphotransferase (PST).

Reference-Hunter, J.O. “Food Allergy or Enterometabolic Disorder,” Lancet 338 (1991): 495–96.


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