What Is a Food Sensitivity?

Food sensitivities are a tricky category, and definitions vary. One theory suggests that, like allergies, they may involve an immune response, though they activate a different antibody, immunoglobulin G (IgG). “Food sensitivity is an immunologic reaction in the same way that allergy is, but it’s delayed, with reactions usually occurring after hours or days,” says naturopathic doctor Sara Jean Barrett, ND, a holistic and functional-medicine practitioner in Minneapolis.

Gluten, corn, dairy, soy, and eggs are some of the best-known triggers for food sensitivities. Reactions can include joint pain, stomach pain, fatigue, rashes, and brain fog.

“Food sensitivity is an immunologic reaction in the same way that allergy is, but it’s delayed, with reactions usually occurring after hours or days.”

Because symptoms of food sensitivity often occur hours or days after a food is consumed, identifying triggers can be more of a challenge. “If you eat something on Monday and have a migraine on Wednesday, it can be harder to connect the cause and effect,” says naturopath Dan Lukaczer, ND, director of medical education at the Institute for Functional Medicine.

Many tests claim to identify sensitivities by testing for IgG antibodies. But unlike allergy tests, IgG tests aren’t standardized, and many providers believe they should be used with caution. False positives are common, and a test may indicate that someone is creating IgG antibodies against a food that isn’t causing any negative reactions.

“If you’re eating something and have no symptoms, don’t take it out of your diet just because a test shows something,” says Northwestern University pediatrics and medicine professor Ruchi Gupta, MD, MPH, author of Food Without Fear: Identify, Prevent, and Treat Food Allergies, Intolerances, and Sensitivities.

Others feel differently. Lukaczer believes that IgG tests can be valuable if used judiciously. “You have to use tests with a degree of balance in the context of each patient.” If someone is experiencing symptoms, a food-sensitivity test can help inform treatment.

“The gold standard of testing is eliminating a food and seeing if there’s improvement. An IgG food-sensitivity test gives me a road map to see which ones we may want to assess,” he says. “It can help narrow the field.”

This was excerpted from “Making Sense of Food Allergies” which was published in the May 2022 issue of Experience Life magazine.