Food Sensitivities and Immune Reactions

In concise terms, food sensitivities are type-3 and type-4 immune reactions to certain foods. Some people speak of food sensitivities as being in the general category of food allergies, but most allergists would not agree with this label. True food allergies are usually a type-I immune response — a response that can sometimes be life threatening such as, for example, with some person’s peanut allergies, which can trigger anaphylactic shock.

Also, food sensitivities are not the same as food intolerances. Food intolerances usually indicate the inability to digest a given food. A common example of this would be lactose intolerance, which is caused by a person being deficient in the digestive enzyme lactase. Food intolerances generally don’t involve the immune system.

Before I can go further, I should explain more about the basic process of the immune system.

From a high-level view, here are the steps of an immune response:

  1. An external stimulus triggers the immune system; that is, the immune system identifies some substance as “foreign” and requiring a defensive reactions.
  2. Then the immune system releases chemicals called mediators. There are many mediators including histamine, cytokines, prostaglandins, and more — there are roughly 100 different mediators. There are various mechanisms that cause mediator release. Humoral mechanisms release antibodies (such as IgE, IgG and IgM — and these antibodies such as IgE then trigger the release of mediators) and compliment (C3 and C4). Cellular mechanisms trigger cellular reactions (T-cells, phagocytes, granulocytes and NK cells).
    There are also non-immune processes that deliver mediators within the body including eating foods containing lectins and histamine.
  3. Mediators then trigger the actual immune defense process, AND, most importantly, mediators can, in some persons, trigger the symptoms that we perceive as clinical illness.

Mediators are found in white-blood cells (WBC) and in circulation, but are primarily from WBC. Different types of WBC include mast cells, basophils, eosinophils, macrophages, monocytes, neutrophils, NK cells (natural-killer cells), and T cells.

Immune-system reactions are also classified by type. Type-1 reactions are IgE mediated (or, more accurately, have an IgE mechanism that causes mediator release). These are true allergic reactions and are the main type of immune response addressed by allergists. There are common tests to determine IgE reactivity. The skin-prick or skin-scratch tests are best to determine environmental allergens, but are not as accurate for finding food allergens. The best way to find food allergens is via a blood test. These tests are commonly performed by physicians.

Type-3 and type-4 immune reactions pertain to food sensitivity.

Type-3 reactions rely on antigen-antibody complexes that activate compliment, which in turn attracts neutrophils that degranulate and release tissue-damaging enzymes. Complexes present in too large a quantity to be appropriately cleared by the innate immune system attract leukocytes, which then can release mediators that create an inflammatory response that underlies many so-called immune-complex diseases including lupus, rheumatoid arthritis, and reactive arthritis.

Type-4 reactions are cell mediated, not involving antibodies — only T-cells and granulocytes. Irritable-bowel syndrome (IBS) and migraine headaches are most commonly type-4 reactions.

The following chart summarizes the immune-type reactions involved in food allergies (type 1) and food sensitivities (types 3 and 4):

Type 1 Type 3 Type 4
Cells Involved In Mediator Release Mast Cells
Basophils
Eosinophils
Neutrophils
Basophils
Macrophages
NK cells
Eosinophils
Monocytes
Neutrophils
Basophils
Macrophages
NK cells
Eosinophils
Monocytes
T Cells
Mechanisms
Involved In Mediator Release
IgE IgG
IgM
Complement
T-Cell Mediated

In  my work with clients, we focus on finding and eliminating foods that trigger type-3 and -4 reactions, and, most importantly, foods that don’t trigger immune reactions. We use the mediator-release blood test (MRT) as the STARTING point for the LEAP protocol, which initially puts the client on a non-triggering diet to allow the immune process to quiet and calm. Then as the protocol progresses, new foods are added in a very controlled, structured way to identify foods that are triggering counter-productive immune responses, and then eliminate those triggering foods from the clients diet.

 

 

 

Author: Doug Hansford

Registered Dietitian/Nutritionist — trained in university and hospital; certified by the Commission on Dietetic Registration (RDN credential) and by Oxford Biomedical Laboratories (CLT credential). Member of the Academy of Nutrition and Dietetics. Specializing in food sensitivities treating irritable bowel syndrome (IBS), migrane, fibromyalgia, and other conditions related to food sensitivities, which can include asthma, eczema, heartburn/GERD, arthritis, joint pain, chronic fatigue, chronic sinusitis, skin eruptions, and autism/ADD.

Also a former certified personal trainer and part-time lecturer in the department of nutrition and food science at a major research university.