You are here: -
Food Antibody Profiles
Frequently asked questions
Q. Will the test show a positive IgG4 response to a food that I have not been eating for over a month?
A. No, unlike IgE antibodies that can persist in blood for years, IgG4 food antibodies decline within one month of eating the food.
Q. Does a positive IgG4 response on my test mean that I am allergic to the food and should not eat it ever again?
A. No. A positive IgG4 food antibody response is defined as an abnormal response to a food that is habitually eaten. The relevant IgG4 food antibodies go on to form large, stable antibody-antigen complexes that can then deposit in tissue and lead to inflammation, pain and fatigue.
Q. What are the main differences between IgE and IgG food reactions?
A. See table below.
|
Characteristic of IgE & IgG-Mediated Reactions to Food
|
|
|
IgE Mediated
|
IgG Mediated
|
|
Incidence is relatively low
|
Incidence is relatively high
|
|
Result from infrequent exposure
|
Result from frequent exposure
|
|
Very predictable short term symptoms
|
Chronic, variable symptoms
|
|
Offending food is usually obvious
|
Offending food frequently not suspected
|
|
Basophil/mast cell triggered anaphylaxis
|
Immune complex trigger
|
|
Histamine/Leukotriene release
|
Inflammatory response
|
|
Patient aware of offending food
|
Patient rarely aware of offending food
|
|
Antibody persistent for years
|
Antibody declines within one month
|
|
In vitro testing for serum IgE for confirmation
|
In vitro testing for serum IgG4 shows food offenders and extent of gut permeability
|
|
Treatment:
Permanent food avoidance and immunotherapy
|
Treatment:
Eliminate then rotate food(s), heal gut, improve digestion
|
Q. Why has my doctor ordered an IgG4 Food Antibody test for me and not an IgE Food Antibody test?
A. As highlighted above, IgE mediated reactions are normally easy for a patient to pick up, as the symptoms usually appear minutes after ingesting the offending food. IgG mediated food reactions are the opposite; symptoms appear hours or days after ingesting the offending food, which makes detection much harder. For this reason, many healthcare practitioners will choose to do an IgG4 food antibody test to determine what foods may be contributing to a patient’s symptoms.
Q. There are some foods that I eat which often give me bloating or gas; however these foods did not come up on my IgG4 Food antibody test. How do you explain this?
A. The IgG4 Food Antibody test measures only one common type of food antibody response. There are a number of other mechanisms by which a food can cause adverse symptoms in an individual. Some of these examples include:
1. Food intolerance: An undesirable reaction to food that does not involve the immune system, such as lactose intolerance, where due to genetic factors, individuals lack the enzyme to digest lactose, leading to loose stools, gas and nausea when ingesting milk.
2. Food Allergy: An abnormal response to a specific food triggered by the mast cell histamine release, such as hives and anaphylaxis caused by an allergy to peanuts. This type of food reaction is caused by IgE antibodies.
3. Physiological overload: The small intestine of humans has a limited ability to absorb certain short-chain carbohydrates (i.e. fructose) and sugar alcohols (i.e. maltitol, sorbitol, isomalt, and xylitol). People who consume amounts of these substances beyond their physiological absorption capacity typically experience symptoms such as bloating, gas and diarrhea. Breath testing is normally used to diagnose this type of food reaction.
Q. For some time I have been suspicious that I have a sensitivity to wheat but it did not come up positive on my IgG4 Food Antibody test. Is this a flaw in the test?
A. No. Sensitivity to wheat is not normally mediated by IgG4 food antibodies. IgA reactions to gliadin (a protein component of wheat) are the most common form of food sensitivity to wheat.
