There is often a lot of confusion about terminology when we discuss food and the reactions it can trigger.
Food allergies are an allergic reaction caused by a reaction of the body's immune system to specific proteins in a food.
According to a recent publication approximately 7% of Canadians self-report a food allergy. However, fewer are likely to have a physician-diagnosed food allergy, which are estimated at prevalence levels up to 5-6% for young children and 3-4% for adults in westernized countries.
In allergic individuals, a food protein is mistakenly identified by the immune system as being harmful. The first time the individual is exposed to such a protein, the body's immune system responds by creating antibodies called immunoglobulin E (IgE). When the individual is exposed again to the same food protein, IgE antibodies and chemicals such as histamine are released. Histamine is a powerful chemical that can cause a reaction in the respiratory system, gastrointestinal tract, skin or cardiovascular system. In the most extreme cases, food allergies can be fatal. Although any food can provoke an immune response in allergic individuals, a few foods such as peanuts, shellfish, and eggs are responsible for the majority of food allergies.
A food sensitivity is an adverse reaction to a food mediated by a different arm of the immune system and produces Immunoglobulin G (IgG). In an IgG reaction, the IgG antibodies bind to food antigens creating antibody-antigen complexes. These complexes are normally removed by immune system cells called macrophages. However, if complexes are present in large numbers and the reactive food is still being consumed, the macrophages can’t remove them quickly enough. The food antigen-antibody complexes accumulate and can be deposited in body tissues. Once in tissues, these complexes can trigger inflammation, which may be responsible for a wide variety of symptoms.
Generally they are delayed reactions (Eg. you eat an egg for breakfast and get a headache later that afternoon) which makes them hard to diagnose. I commonly use a test called a Food Sensitivity Blood test that helps to diagnose over 120 different foods and has shown incredible results in my patients.
A food intolerance is a food sensitivity that does not involve the individual's immune system. Unlike food allergies, or chemical sensitivities, where a small amount of food can cause a reaction, it generally takes a more normal sized portion to produce symptoms of food intolerance. While the symptoms of food intolerance vary and can be mistaken for those of a food allergy, food intolerances are more likely to originate in the gastrointestinal system and are usually caused by an inability to digest or absorb certain foods, or components of those foods.
For example, intolerance to dairy products is one of the most common food intolerances. Known as lactose intolerance, it occurs in people who lack an enzyme called lactase, which is needed to digest lactose (a sugar in milk.) Symptoms of lactose intolerance may include abdominal pain and bloating, diarrhea and flatulence.
I do a type of food sensitivity/intolerance testing called Allergy Treatment Protocol (ATP) in order to help determine what might be causing various intolerances.
Chemical sensitivities occur when a person has an adverse reaction to chemicals that occur naturally in, or are added to, foods. Examples of chemical sensitivities are reactions to: caffeine in coffee, tyramine in aged cheese and flavour enhancers like monosodium glutamate (MSG).Celiac disease is not a sensitivity or allergy but a genetic disease and the symptoms are triggered by the consumption of gluten. The main sources of gluten in the diet are cereal grains and the only current treatment for celiac disease is to continually maintain a strict gluten-free diet.