There have been many studies demonstrating that IgG antibodies to foods indicate an allergy that can produce a wide variety of symptoms, including IBS.
Definitions to understand for this study:
Antibody – also known as an immunoglobulin (Ig), is a large Y-shaped protein produced by B-cells that is used by the immune system to identify and neutralize foreign objects such as bacteria and viruses.
Immunoglobulin G (IgG) and Immunoglobulin E (IgE) are both antibody isotypes.
The opinion (unsupported by research) of many doctors, particularly allergists, has been that allergies can only be caused by immunoglobulin type E antibodies (IgE). It has even been stated as commentary in research papers (again, not based on hard evidence) that the presence of IgG antibodies indicates that the patient is tolerant of the food.
This does not make sense when you consider that tolerance is when your body makes NO antibodies to the food. Your body does not waste precious energy and resources making antibodies to things it tolerates.
There have been many studies demonstrating that IgG antibodies to foods indicate an allergy that can produce a wide variety of symptoms, including IBS. Now we have a study that shows that IgG antibodies are associated with conventional peanut allergy as well. Again, it’s associated with the peanut allergy – not as a tolerance.
The study from National Institutes of Health:
Peanut sensitization during the first 5 yr of life is associated with elevated levels of peanut-specific IgG.
Allergen-specific IgE antibodies are implicated in allergic diseases while allergen-specific IgG antibodies have been proposed to prevent allergic reactions. The objective for this study was to study whether the immune response (IgG and IgG4) to peanut differs in IgE-sensitized and non-sensitized young children.
A total of 239 children have been followed prospectively from birth to 5 yr of age. The levels of IgG and IgG4 to peanut, Ara h 2, and Ara h 8 were analyzed at 2 and 5 yr of age and related to IgE sensitization and peanut consumption.
The levels of peanut-specific IgG and IgG4 were significantly higher in peanut-sensitized children at 2 and 5 yr of age when compared with non-sensitized children and children sensitized to other food/inhalant allergens. A strong correlation was seen between levels of peanut-specific IgG/IgG4-ratios and peanut-specific IgE at 5 yr of age. Children avoiding peanuts, a subgroup of the peanut sensitized, had statistically significant higher levels of IgE to peanut and a tendency of higher IgG and IgG4 levels to peanut. In the avoidance group, significant correlations between IgE and IgG/IgG4 to peanut were found compared with children eating peanuts.
Peanut-specific IgG or IgG4 levels were elevated in peanut-sensitized children especially those avoiding peanuts. In our study, IgG and IgG4 do not seem to indicate tolerance or protection from sensitization.
Image thanks to leavedebtbehind
Definitions provided by wikipedia