“What is food to one man may be fierce poison to another”– Lucretius circa 756BC

The types of cases I see in clinic seem to follow trends.  Two months ago I was seeing lots of skin conditions, last month I saw many patients with mood or stress complaints.  This month I’m getting lots of questions about food sensitivities and allergies.  There seems to be a lot of confusion about what exactly a food sensitivity is, versus a food allergy or a food intolerance.  So let’s talk about it and get it all cleared up, shall we?
An ALLERGY causes an immediate reaction within 15mins of eating or sometimes touching the food.  It is classified as an Immediate Hypersensitivity reaction, where immunoglobulin IgE antibodies “mark” the proteins in the food as foreign.  The immune system reacts by releasing histamine and other allergy mediators which cause symptoms like digestive upset, hayfever (in the case of environmental allergies) or anaphylaxis.  Some foods that commonly cause this type of reaction are peanuts, dairy and eggs.  Food allergies affect roughly 2% of the population.
A SENSITIVITY causes a delayed reaction, usually hours to days after eating the food.  It is classified as a Delayed Hypersensitivity reaction involving the IgG antibody.  Food sensitivities can cause a wide array of symptoms such as diarrhea, constipation, bloating, nausea, eczema, brain fog, nasal congestion, behavioural problems in children, fatigue, headaches, etc…  They are also more difficult to pinpoint because the reaction is not immediate.  Food sensitivities can develop or disappear at any age, and affect approximately 20% of the population.  Common food sensitivities are wheat, dairy, corn, soy, eggs and others.
A food INTOLERANCE is simply an unpleasant reaction to a food or the result of lacking a specific enzyme required to break down a food.  An intolerance does not involve an immune reaction.  A common example of this is a lactose intolerance or a reaction to sulphites in food.
There are many ways of testing for food allergies and sensitivities.  Food allergy testing is done by an Allergist and involves a skin scratch test where a number of allergens are tested on the thin skin of the forearm or the back.  Food sensitivity testing is done by a Naturopathic Doctor and commonly involves an in office finger prick or in lab serum blood test, or in some clinics some form of electro-dermal testing like VEGA testing or BIE.  The “gold-standard” to identify food sensitivities is an Elimination Diet, where one eats a simple hypoallergenic diet for approximately 1 month, then reintroduces one food at a time and observes for any recurrence of symptoms.  This gives us the most valuable information, but it is also the most high maintenance of the testing options. Once the sensitivity is identified, it is recommended to avoid it for at least 3 months, while taking steps to heal the digestive tract.  Some supplements that help to reduce inflammation and heal the tissue in the digestive tract are fish oils and probiotics.  Digestive enzymes or apple cider vinegar can improve digestion and ameliorate digestive symptoms such as constipation and gas or bloating.
It is important to identify any offending foods, not only to eliminate unpleasant symptoms, but also to decrease the overall inflammatory state that results from untreated food reactions.  Please feel free to post any questions you have about food allergies/sensitivities/intolerances in the comments section, I’d be happy to answer them.