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Stanford study shows lack of criteria for diagnosing food allergies

glass of milk.jpg

When I was in elementary school several decades ago, I had a classmate who was allergic to milk. It was the oddest thing, I thought, and I remember being fascinated by the special (non-dairy) cookies she brought in her lunch-box and occasionally shared with the rest of us. They tasted funny.

Back then, food allergies were a novelty - but these days, they're commonplace. (Who doesn't know someone who can't, for example, consume dairy?) While it would be easy to assume that the prevalence of this condition is on the rise, a new Stanford analysis of existing medical literature suggests that some patients may be getting misdiagnosed.

The reason for this potential problem? There's not a consistent set of criteria in the field for identifying the condition, and two commonly used diagnostic tests, a skin-prick test and blood test, are less than definitive. From my release:

...Patients with non-specific symptoms, such as a rash or digestive troubles, and positive skin-prick or blood tests actually have less than a 50 percent chance of having a food allergy. In order to make a proper diagnosis, [the researchers] pointed out, physicians need to evaluate the data within the context of a patient’s history and have a great understanding of symptoms consistent with true food allergy...

“I frequently see patients in my clinical practice who have food intolerance, but have previously had inadequate or inappropriate evaluation and been told they have a ‘food allergy’,” said [co-author Marc Riedl, MD, MS, section head of clinical immunology and allergy at UCLA].

Why is this important? As Stanford researcher and lead author Jenny Chafen, MD, told me, "the distinction between food intolerance and food allergy is really important." A true food allergy can have a major effect on patients' overall health and quality of life, and getting the proper treatment - based on the proper diagnosis - is critical.

In their study, which also looks at treatment and prevention strategies, Chafen and her colleagues call for a standardized criteria of what constitutes a food allergy and a set of guidelines upon which to make a diagnosis. ("Then we can move forward more quickly on management and prevention," Chafen said.) The National Institute of Allergy and Infectious Diseases, which funded Chafen's work, is working on such guidelines now.

The study appears in the current issue of the Journal of the American Medical Association.

Photo by JonathanCohen

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