Self-reported multiple food intolerances/sensitivities have been reported to be frequently associated with Idiopathic Environmental Intolerance (IEI), formerly called Multiple Chemical Sensitivity (MCS) Syndrome . In 1987, Cullen introduced the term “multiple chemical sensitivities,” which he defined as “An acquired disorder characterized by recurrent symptoms, referable to multiple organ systems, occurring in response to demonstrable exposure to many chemically unrelated compounds at doses far below those established in the general population to cause harmful effects. No single widely accepted test of physiologic function can be shown to correlate with symptoms.” Other terms for IEI/ MCS are cerebral allergy, chemically induced immune dysregulation, total allergy syndrome, and ecologic illness.
The most common complaints are fatigue, headache, nausea, malaise, pain, mucosal irritation, disorientation, and dizziness, which are mostly non-specific. No gross or microscopic evidence of inflammation or other objective signs of pathology have been associated with IEI/MCS. As in somatoform disorders, these patients have multiple chronic symptoms and have previously consulted with numerous physicians and other health care professionals without satisfaction nor any finding of underlying immunologic, autoimmune, or any physical disease to explain their symptoms. Patients attribute their illness to exposure to a combination of environmental chemicals, multiple foods, and drugs. A unique feature of IEI is the general absence of a dose-response curve in the provocation of symptoms.
Evidence is growing in support of a causal role of underlying psychiatric illness, specifically somatoform, depression, and panic disorder in IEI/ MCS. IEI and panic disorder share common symptoms such as chest tightness, breathlessness, and palpitations; apprehension; and avoidance of situations that have been associated with onset of symptoms. Panic attacks may temporarily occur with non-noxious stimuli that are then associated with symptoms by the patient and are subsequently considered the cause of the symptoms. Reports of placebo-controlled studies using saline infusions, carbon dioxide inhalation, and provocative challenges note that these approaches provoke symptoms suggestive of panic disorder and anxiety syndrome with hyperventilation in IEI/ MCS patients. Evidence for a common neurogenetic basis linking IEI and panic disorders was reported in a study of 11 IEI patients who were found to have a significantly increased prevalence of cholecystokinin B (CCK-B) receptor alleles, which are known to be associated with panic disorder, compared to age-, sex-, and ethnic background-matched controls.
From: “Psychological Considerations in Food Allergy” Chapter in Food Allergy: Adverse Reactions to Foods and Food Additives, 3rd ed, Blackwell Science