Dr. Elana Lavine, from the Department of Pediatrics at Humber River Regional Hospital in Toronto, wrote that both traditional and complementary practitioners may offer blood testing to identify foods that could play a role in a patient's illnesses. However, the differences between food allergy - a specific immune response that occurs with exposure to a particular food - food intolerance, such as lactose intolerance, and food sensitivity, may not be clear to many patients.
"Food sensitivity is a nonspecific term that can include any symptom perceived to be related to food and thus may be subject to a wide range of usage and interpretation," she wrote.
In particular, Dr. Lavine writes that immunoglobin G (IgG) antibody testing and IgG4 testing may be misleading - and results of IgG4 testing may be misinterpreted to indicate food sensitivity or intolerance, even though IgG4 is thought to be a marker of exposure to a food, or even of tolerance.
The test is also available online and at pharmacies, and checks IgG levels in response to a wide range of foods, "many of which are ubiquitous, difficult to avoid or very rarely documented as food allergens".
IgG is released in response to foods, but is not a reliable marker for allergy or sensitivity tests, she said.
"Physicians should caution patients about the controversy surrounding testing for food sensitivity," Lavine wrote, adding that doctors may find it useful to explain the "paucity of evidence for using these tests to diagnose food allergy or guide elimination diets".
The American Academy of Allergy, Asthma, and Immunology also takes the position that measurement of specific IgG antibodies to foods is unproven as a diagnostic tool.
Earlier this month, researchers writing in the Annals of Internal Medicine argued that increasing diagnosis of non-celiac gluten sensitivity may also lead to needless dietary limitations.
Source: Canadian Medical Association Journal
CMAJ 2012. DOI:10.1503/cmaj.11002
"Blood testing for sensitivity, allergy or intolerance to food"
Author: Elana Lavine