Food Allergies and Food Intolerance’s
Food Allergies and Food Intolerances
by Hope Pearce, ND
What are food allergies?
A food allergy is one type of adverse food reaction that is mediated by the immune system. An immune reaction occurs in response to food proteins which are unique to the affected individual. Immunoglobulins (antibodies) are produced by our immune system against each specific allergen that is deemed to be dangerous or potentially disruptive to our own metabolism.
Problems develop when the immune system is hyper responsive causing antibodies to attach to antigens The antibodies mediate significant inflammatory processes as part of this defensive action and a variety of other internal reactions. Allergic symptoms are the direct results of these antibody caused processes.
Why do allergies develop?
Genetic predisposition, infections and inflammation, unbalanced or inadequate diets, chemicals, drugs, stress, environmental pollutants and toxins are all possible contributing factors in the development of allergies.
Research has shown that these factors may weaken both digestion as well as the protective defences in our intestinal tract and lungs allowing for allergens to more easily confront our overwhelmed immune system.
What is the difference between food allergies and intolerances?
May people get confused and think that and think that all food reactions are allergies, in fact a true food allergy is quite rare with only about 2.5% of the population being diagnosed with this condition. Many reactions are in fact intolerances.
A food allergy is one type of adverse food reaction that is mediated by the immune system. An adverse food reaction or a food intolerance may comprise any symptom following the intake of a food. Symptoms may be any perceptible change in how we feel and/or function. A symptom may present, for example, as a rash, achy joints, or fatigue. Many people with food intolerances experience more than one symptom and symptoms can be vague such as feeling tired or experiencing brain fog. Often these symptoms cause people to visit their Doctor and to have blood tests but they are usually told “nothing is wrong”. A food intolerance is where the body cannot completely digest a food. This is usually due to lack of a certain enzyme e.g. lactose or enzymes or lack of stomach acid.
Both food allergies and food intolerances cause intestinal damage which can results in intestinal permeability. Food intolerances can lead to food allergies.
There are four ways the immune system attacks antigens:
Type I – Immediate Hypersensitivity Reactions
This type of allergic reaction is mediated through IgE antibodies. Typically IgE reactions occur less then 2 hours after eating the allergen. The IgE antibodies bind to mast cells (resident cells of connective tissues containing allergy mediators) and basophils (a type of white blood cell containing allergy mediators) located in human tissue. The next time the person comes into contact with the allergen the mast cells and basophils will release potent chemical mediators such as histamine causing an allergic reaction. Such a reaction may cause anaphylaxis which is a life-threatening reaction and requires immediate medical attention. This is often called a true allergy people who have this type of allergy usually know they have them, and they often appear at an early age.
Everybody has IgE antibodies but an allergic person produces high levels of IgE antibodies to attack the allergens. If you have an IgE reaction to food the allergic food will need to be avoided for life as reactions can be life-threatening. Typical allergic responses are: runny nose, itchy eyes, wheezing diarrhoea, swelling, vomiting, restricted airways, eczema, hives.
Type II – Antibody-Mediated Cytotoxic Hypersensitivity
This type of reaction refers to an immune response being triggered by cell-bound antigens (i.e. antigens that are attached to the body’s own cells. These cell-bound antigens can be either intrinsic (part of the body’s own cells) or extrinsic (from an external, ingested source). Once the body recognises these antigens it responds by binding IgG and/or IgM antibodies to the antigens (and thus to the cells) to form the complexes that trigger the immune system’s attack response. This immune attack response not only destroys the antigen-antibody complex, but the body’s cell it is attached to as well. The process time for a type II reaction is usually a few hours to one day and results in the destruction of the body’s cells as well as the antigen-antibody complexes attached to them. Some examples of this would be: Autoimmune Haemolytica Anaemia, reactions to transfusions, certain drug reactions.
Type III – Delayed Hypersensitivity Reactions.
This type of reaction can involve IgG and IgE antibodies but more commonly involves IgG antibodies. IgG forms an immune complex with the allergen/antigen (Ag), (could be any food, cheese, banana’s etc) which activate the complement pathway and releases inflammatory mediators wherever the immune complex is deposited. This can take anywhere from several hours to several days which is why the hypersensitivity reactions are delayed. Although macrophages (white blood cells) pick up the IgG-Ag complexes immediately, they have a finite capacity to do so, If there are a lot of antigens present, the macrophages may saturate their capacity to remove the immune complexes, causing the excess complexes to be deposited in tissue. The symptoms depend on what tissue the complexes are deposited into. For example complexes be deposited between the joints leading to inflammation and this mechanism is thought to be contributing factor to Rheumatoid Arthritis. These complexes may be deposited anywhere such as the head, lung’s, gastro-intestinal tract, skin and joints where they produce symptoms such as headaches, asthma, irritable bowel syndrome, eczema, and arthritis.
Type IV – Cell Mediated Immune Response.
This response is mediated by T cells rather than antibodies. This usually causes a delayed reaction between 36 to 72 hours and is typical in conditions such as contact dermatitis. This response occurs when an allergen makes contact with a mucosal surface such as the intestinal tract.
How do you know what to test for?
At Purely Health we find that the majority of our patients are exhibiting symptoms caused by a Type III Delayed Hypersensitivity Reaction, usually caused by IgG antibodies but sometimes IgE antibodies are also involved. We can send you for a simple blood test through Medlab to determine if you have high levels of IgE antibodies. If your results come back within the normal range we would then usually reccomend a delayed IgG food intolerance test depending on what has come out of your consultation.
Why do foods cause an IgG delayed response?
When digesting the food we eat our bodies break down food into smaller components e.g protein into amino acids. Usually these molecules pass harmlessly through the gut into the bloodstream. When there is increased permeability in the intestinal mucosa small fragments of partially digested or undigested foods can pass through the intestinal wall. This condition is commonly known as leaky gut. The immune system then recognises these particles as ‘foreign’ and responds by making IgG antibodies.
Why does the mucosal barrier of the gut become leaky?
Poor diet, pro-inflammatory foods such as alcohol and caffeine which irritate gut wall, chemicals found in processed foods, toxins, chronic stress, imbalanced gut flora, certain medications such as NSAID’s, Antibiotic over use, parasites, Candida are just a few of the many possible causes of leaky gut.
Common tests for Allergies
The most common tests that are performed at your local G.P for allergies are a skin prick test or a RAST test. Both of these tests only test for IgE mediated allergies. Both of these methods have their advantages and disadvantages. These tests do not test for Delayed Food Allergies - Type III or IgG Response. Some reports state that delayed food reactions may account for as much as 90% of food reactions.
Purely Health offers two types of delayed IgG testing:
Delayed IgG ELISA test done through US Biotek. US Biotek are pioneers in ELISA technology with over 30 years experience. 96 Different foods are tested including the foods from the following groups of Dairy, Seafood, Vegetables, Fruits, Condiments, Meat & Eggs etc. Additional tests can be done for vegetarians and spices etc. A small blood sample is taken by a finger prick in the consultation process and then the sample is sent of to the laboratory. Results take 2-4 weeks.
IgG Food Detective Intolerance Test kit. 50 foods are tested during a consultation and the results take less than 50 minutes. A small blood sample is taken from a finger-prick and is then diluted and added to the tray. In subsequent steps the use of detector and developer solutions identify the presence of food antibodies through the appearance of one or more blue spots on the tray. You will have your results by the end of the consultation.