Yesterday’s article in the New York Times on food allergies presents an opportunity to clarify the distinction between food allergies and food intolerances. The article cites Dr. Marc Riedl, allergist and immunologist at UCLA who was recently commissioned to author a report on food allergies for the federal government. Dr. Riedl accurately comments on the fairly low prevalence of true food allergy – roughly 5% for adults and 8% for children.
By true food allergy is meant a Type I, acute immune hypersensitivity reaction mediated by a type of antibody called immunoglobulin E, or IgE. Evaluation by allergy and immunology specialists for IgE food reactions are typically conducted via blood testing for IgE antibodies or by performing skin prick tests for food reactions. True IgE-mediated food allergies are the type of hypersensitivity to foods causing severe responses including anaphylaxis and death. This type of food allergy is relatively rare, and occasionally false-positive reactions to foods can occur on testing.
Other types of reactions to food, frequently mislabeled “food allergies,” are in fact food sensitivities. These reactions may also present with an immunological reaction to foods and are mediated by immunoglobulins type A and G. The presence of IgG or IgA antibodies to foods correlate to delayed hypersensitivity reactions and commonly present as chronic symptoms such as digestive complaints and skin rashes. Evaluating for food sensitivities can be done by testing saliva or blood, or by performing an Elimination/Challenge diet. Studies that assess testing methodology have demonstrated inconsistencies with salivary IgA and serum IgA and IgG testing, with unclear sensitivity and specificity and a good deal of variability between laboratories. Today the “gold standard” for evaluating food sensitivities is considered to be the Elimination/Challenge Diet, in which select foods are eliminated for a minimum of three weeks and gradually reintroduced one at a time. The findings of this test are empirical and subjective, and certainly more challenging for a patient that simply getting a blood test. However, the clinical relevance of how much better one feels after eliminating reactive foods, confirmed with a return of the symptoms when the food is reintroduced, is significant.
An important clarification regarding the Elimination/Challenge diet is that this assessment is appropriate for identifying food sensitivities, not food allergies. It would be inappropriate and dangerous to attempt a “challenge” of foods suspected of causing acute hypersensitivity reactions, such as a peanut allergy, which can be life-threatening. Unlike the incidence of true food allergy, the incidence of food sensitivities is very common. As mentioned in the article, as much as 30% of the population believe that they have a food allergy – a misnomer for food sensitivity or intolerance. The actual prevalence of food sensitivity may be even higher than 30%, given the widespread use of prescribed and over the counter antacid medications for reflux and indigestion.
Which brings me to the most important point from a Naturopathic perspective of Identify and Treat the Cause: the food sensitivity, although often a hidden or overlooked aggravator of many chronic health problems, may be in fact merely a symptom of underlying maldigestion and not the causal factor itself. The prevalence of food sensitivities correlates with rising incidence of GERD, maldigestion associated with greater consumption of refined food, a low-fiber diet, overeating, eating too quickly, elevated stress levels, and impaired digestive function. While identifying and eliminating food sensitivities can greatly improve a patient’s chronic symptoms, digestive health must be addressed to fully resolve the underlying cause and prevent further sensitivities and greater dietary restrictions.
More information on food sensitivities can be found at Alletess, a laboratory specializing in food sensitivities (despite the incorrect usage of the term “food allergies” on their website), and from the following resources:
The Anti-Inflammation Diet and Recipe Book by Jessica Black, ND
Coping With Food Intolerances by Dick Thom, ND
