Reactions to foods are increasingly common, with a large portion of the population experiencing some reactivity or sensitivity.
The definition of true food allergy is a type of immune reaction that occurs after eating certain foods. The prevalence of food allergies has been sharply rising, and is estimated to affect 7% of young children and 3% of adults.
The most common food allergies are to: milk (casein and whey), eggs, wheat (gluten), soy, peanuts, tree nuts, and shellfish
Usually these reactions will occur less than 2 hours post exposure to the allergen. This is an antigen/antibody reaction where the person must have been exposed in the past to have this kind of "immune recognition."
The antibody created in this reaction, immunoglobulin E (IgE), will bind to certain immune cells causing the release of histamine and other cytokines, possibly causing reactions in the following:
- Skin - hives and itching (pruritis);
- Gastrointestinal Tract - diarrhea, vomiting;
- Airways - wheezing, coughing, phlegm, swelling and mucous secretion in nasal passages, asthma, and hay fever;
- Blood Vessels - increased fluid leaks into tissues, causing swelling and in severe cases anaphylaxis.
In contrast to IgE Food Allergies, Non-IgE Food Allergies can be extremely challenging to identify but contribute much more often to a person's health picture.
Non- IgE mediated food sensitivities are what we refer to as food intolerance. They may not trigger the immediate IgE reactions but they still cause immune activation and symptoms.
These tend to have a more delayed picture and the onset of symptoms can occur hours to days after food ingestion.
Symptoms may include feeding difficulties in an infant, vomiting/GERD, persistent diarrhea, failure to thrive and rectal bleeding. They may contribute to chronic inflammation in the intestines as well as eczema.
For blood testing, there are several options, but Dr. Sierra prefers the direct measurement of IgG and IgE antibodies in order to simultaneously find food intolerances and food allergies.
There are dietary methods for food intolerance testing (described below), but for ease, immediacy and clinical relevance the testing is superior.
Dr. Sierra regularly uses the Meridian Valley food testing panel (click here to view a sample patient's results).
The Elimination Diet is the gold standard as far as clinically discovering the source of a food intolerance or allergy. Although testing can give a framework, removing and re-introducing foods into your diet every few days can help to pin point the causative factors. This can be a long/ drawn out process, but can be helpful for identifying reactions that don’t seem to be clearly identified by testing.
By far Dr. Sierra's favorite test is the IgE/IgG food sensitivity test by a lab pioneer in the category of food allergy/intolerance detection. This approach is most helpful for guiding her patient's optimal nutrition plan and tailoring it to their individual sensitivities. Naturopaths can help their patients dig deeper to find their hidden/delayed intolerances to foods, and create a customized plan for eating well, using principles of avoidance and rotation to optimize heath.