Food intolerances and food allergies, it is what everyone is talking about. Everywhere you look there are gluten free products, peanuts have been banned from schools and airplanes and it seems everyone has foods they think they have to avoid or eliminate. But is this really as big of an issue as it appears? If it is, what is the best way to know if you have a food allergy or intolerance? Although 30 % of people report that either they or their children have food allergies, only 6-8% of children under 5 and 3-4% of adults have clinically proven allergic reactions to foods. Many people confuse an adverse reaction to a food like diarrhea, gas or stomach upset, with an allergic reaction when in fact they are very different.
A food allergy is defined as an adverse immune response toward food proteins, or as a form of food intolerance associated with a hypersensitive immune response. To achieve a clear diagnosis, it should be reproducible and accompanied by a food specific IgE test. The foods that are responsible for the majority of food allergic reactions are milk, egg, peanut, tree nut, seafood, shellfish, soy, and wheat. Food intolerance is a reproducible reaction to a food or food ingredient (examples include lactose or milk intolerance) that is a non-immunological response. You will often hear the word food sensitivity used as well, it 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.
Because of the increased interest in food allergies and food intolerances there are many blood tests or blood print tests offered to the public. These tests often do broad food panel tests and measure antibody binding commonly called IgG or IgG4. Results may be reported to patients as a multipage document that groups foods by category. For example, under “dairy” may be listed cheddar cheese, cottage cheese and so on. Large numbers of foods are tested, which are often difficult to avoid or very rarely documented as food allergens (e.g., sugar, yeast). The degree of “sensitivity” or “allergy” is graded by a classification scale. Based on the scale a list of foods to limit or avoid are provide along with a sample menu. The detection of food-specific IgG shows a physiologic response of the immune system to exposure to food. Seems reasonable to use this as a test for food intolerance. However, this could just be a normal physiological response to the food. In fact, IgG4 is believed to be a marker of exposure to food and possibly of tolerance. Recent position papers from European and American allergy and immunology societies have emphasized the limitations and potential misuse of IgG4 testing, indicating that these tests are not appropriate for making a diagnosis of food allergy. This is not to say that people don’t have intolerances to certain foods. If you have repeated gastrointestinal or other symptoms that are reproducible upon eating a certain food see a gastroenterologist or allergist who will take a careful history. A careful food diary and symptom record can help identify foods or amounts of foods that may be causing symptoms. Often times those with food intolerances find that decreasing the amount or type of the given food relieves symptoms. For example, people with lactose deficiency can sometimes just drink small amounts of milk or consume yogurt and experience no symptoms.
In conclusion, at this time it does not appear that blood print testing is accurate or reliable for diagnosing food allergies or intolerances. It does seem wise not to over consume any one food or food group. In addition, it is one more reason not to consume processed foods and these foods often contain additives like high fructose corn syrup and preservatives that you may be getting more of than you realizes from multiple processed foods. Eating a variety of fresh fruits, vegetables and grains without over consuming any one food is the best way to control and avoid food intolerances.