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Highlights of review article on metal allergy

The below is taken from the BSEM Newsletter:

Disease Variants Implicated in Metal Allergy

(abstract HERE)

A new, remarkable, review of metal allergy should once and for all put an end to the belief that metal allergy causes nothing more than skin reactions. It lists hundreds of publications describing metal-specific allergy responses, identifying over 50 unique manifestations. According to the authors: “metals constitute one of the major classes of allergens responsible for a disproportionately large segment of the total burden of disease associated with allergy.”

Below are some excerpts, which may be of particular interest:


Alopecia areata

It has been reported that in patients diagnosed with all clinical variants of alopecia areata, 70% of those experiencing severe symptoms are hypersensitive to metals. A few specific metals are implicated far more frequently than others, namely mercury, nickel, cobalt and chromium.


Gastrointestinal (GI) issues

Many metals are often present in considerable concentrations in fruits, vegetables, legumes and other foods. Drinking water can also be a major source of metal ingestion; particularly nickel, copper and zinc. Food and water can also be contaminated with lead, cadmium, mercury and arsenic.

Contact allergic gastritis/mucositis is characterized by eruptions of localized inflammation within the epithelial lining of the digestive tract following antigen ingestion. Interestingly, contact allergic gastritis has been almost exclusively associated with metal antigens. Metals that trigger contact allergic gastritis are mainly ingested as a result of their natural occurrence in various food items or following the release of ions from dental material. Clinical symptoms of contact allergic gastritis tend to remain isolated to the GI tract and include stomach upset, cramping, and bloating.

Case report: A patient experienced concurrent GI pain and mucosal lesions shortly after the implantation of a dental bridge and crown. Patch testing revealed reactivity to gold, palladium and zirconium which were present in the dental restorations. These were removed and the patient experienced immediate resolution of both dermal and GI symptoms.


Gastro-esophageal reflux disease (GERD)

Metal allergens have not been implicated in GERD, although several studies have shown a significant correlation between the disease and allergic sensitivity to nickel. Following a low-nickel diet was found in many instances to significantly improve GERD symptoms.


Irritable bowel syndrome (IBS)

Patients with IBS are significantly more likely to react to metals than healthy controls. In one study, 57% of IBS sufferers were hypersensitive to at least one metal. It has been suggested that dental metals, specifically, induce delayed-type hypersensitivity responses within the digestive tract of sensitised individuals, which contributes to disease pathogenesis in a subset of IBS patients. This theory is supported by observations that adoption of a low-nickel diet markedly improved IBS symptoms.


Ulcerative colitis (UC)

A study of patients with UC and healthy controls, all with metallic
dental implants or prosthetics tested for reactivity to various metal allergens. 60% of the UC patients in the study were allergic to at least one metal, compared with 32% of the healthy controls. Nickel and palladium most frequently caused reactions.


Systemic allergic contact dermatitis (ACD)

This is known to emerge following the release of ions from cardiovascular implants, orthopaedic devices, and other surgical implantations containing nickel, cobalt and chromium. Aluminium-based vaccine adjuvants also facilitate development of systemic ACD reactions. In addition, dental materials release metal ions that may be absorbed into the systemic circulation and subsequently trigger widespread ACD eruptions.


Other systemic immune responses

Occurrence of type IV hypersensitivity to metals is elevated in patients with systemic lupus erythematosus, rheumatoid arthritis, chronic fatigue syndrome and Sjogren’s syndrome. In one study, patients with fibromyalgia all tested positive for metal hypersensitivity in the MELISA test. Sensitivity to nickel was most common, followed by inorganic mercury, cadmium and lead. Reduction of metal exposure was achieved by replacement of dental metal restorations and by the avoidance of known sources of metal exposure, which resulted in improved health in most of the patients.