Food Allergens: How the Body Responds and Why We Test

Food allergies occur when the body has an adverse or abnormal response to food. An allergic reaction can be immediate and life-threatening, such as with peanuts. Or it can be delayed, taking three to five days to show up, causing hay fever-like symptoms, tummy troubles, eczema or other skin irritation, or even changes in behaviour and mental focus. This delayed reaction is called “food sensitivity” and is usually not life-threatening.

A true food allergy can be permanent – whenever you eat or are exposed to that food, it will provoke an immune reaction over your lifetime. Food sensitivity happens gradually. Triggers include stress, infection, poor eating habits (e.g., over-consumption of foods with additives, preservatives), or foods exposed to toxins such as pesticides and pollutants. Food sensitivity can lead to chronic health problems, including ADHD, digestive disorders, and persistent infection.

The immune system triggers the body’s response to a food allergen. Protein molecules called immunoglobulin (Ig) circulate in the body via white blood cells. Immunoglobulin (a.k.a. antibodies) very specifically recognize and bind to bacteria, fungus, viruses, or other foreign substances so the immune system can destroy them. Think of immunoglobulins as goblins gobbling up invaders in the body. Once an antibody is produced against a specific invader, the next time it enters the body, the immune system “recognizes” it. It has more of the same antibodies to destroy the invader.

If the root cause of a medical condition can be identified as a food allergy or sensitivity, we can use “food as medicine” to correct the imbalance. A blood test of Ig activity in response to different allergens is done to do this.

Testing for Food Allergies

Several Ig types have different yet synergistic roles in the immune system.

IgE antibodies cause the body to react violently and immediately to things such as pollen, fungus, insect stings, medications, milk, and other foods. IgE levels are often highest in people with allergies, including food allergies. An IgE test covers the major food allergens that produce immediate reactions in the body, such as nuts, eggs, cow’s milk, shellfish, and soy.

IgG antibodies fight bacterial and viral infections. This antibody is found in all body fluids and is typically associated with food sensitivity.

IgA antibodies protect body surfaces exposed to outside foreign substances. It’s abundant in mucus found throughout the body, including the gut; a deficiency in IgA could be tied to adverse responses to food.