In mainstream medicine, understanding the role of food in possible alterations to immune function is largely confined to food allergy. This is an immediate onset immune reaction to foods, mediated by a class of immunoglobulins called IgE, that can result in severe and sometimes life threatening symptoms such as hives, bronchial constriction, and anaphylaxis. What is often misunderstood (or even worse completely ignored) is the far more prevalent and insidious role of food sensitivities in immune alteration and disease progression. Food sensitivities are mediated by a class of immunoglobulins called IgG, and it is primarily through a misunderstanding of the activity of these IgG immunoglobulins that mainstream medicine often discredits their presence as a marker of immune dysfunction.
IgG antibodies are an important part of the immune system – they bind to pathogens such as bacteria, viruses, and fungi, making it easier for them to be identified and destroyed. However the presence of IgG to particular food proteins, especially in high quantities, is an indication that something is amiss. Ideally foods are consumed and digested properly before they are absorbed into the bloodstream. For food proteins, this means the larger protein structures should be broken down into their constituent amino acid building blocks before crossing the gut wall into circulation. However poor digestion (either from mechanical issues such as inadequate chewing, or from a lack of digestive juices and enzymes) coupled with an increased permeability of the gut wall (aka leaky gut) leads to the larger food proteins entering circulation. Over time, the immune system will view these food proteins as a pathogen and mount an immune response to them. This will involve the binding of IgG to the protein complexes, and ideally a clearance of these complexes from the body. However when these IgG food protein complexes reach high levels in the blood, and especially if the immune system is under stress, they are not adequately cleared and can deposit throughout the body. This can then initiate an inflammatory reaction either locally or systemically, producing a range of possible symptoms from sinus inflammation and headache, all the way through to autoimmune disease processes such as rheumatoid arthritis or Hashimoto’s thyroiditis.
It is important to note that the foods themselves are not the drivers of disease – gut dysfunction is the mediator of larger food proteins entering circulation, and not until the causes of this dysfunction are discovered and addressed will true healing take place. However a crucial step on the road to recovery is to identify those foods to which the immune system is mounting a robust IgG response, and remove them from the diet while healing is in progress. The consumption of these foods will perpetuate a chronic inflammatory process and prevent healing from occurring. Often a low to moderate reactivity food can be reintroduced once gut dysfunction has been addressed, however care must be taken to ensure the immune system has re calibrated to avoid hyper-responsiveness to the food protein in question (especially in the case of long standing high sensitivity reaction).
Trying to ascertain IgG sensitivity through dietary consumption and symptom observation is incredibly difficult, owing to the fact that most IgG reactions are delayed (sometimes by a few days) hence tracing a symptom to a particular food is often close to impossible. An accurate way to measure IgG sensitivity is through an ELISA panel test involving a simple process of obtaining a small quantity of blood through a skin prick and mixing this sample in solution. The solution is then applied to a panel of separated food proteins, onto which a reagent solution is added. If there is IgG present in the blood to the food proteins in the panel, the cell containing that protein will stain. Depth of staining indicates the degree of reactivity to that protein. Removal of these reactive foods will be necessary while causes of gut dysfunction are determined and addressed.
If you suspect you may have food sensitivities, testing for specific IgG reactivity to a range of foods is highly recommended as the first step on the road to recovery. Many complementary health practitioners are able to perform this test (I use a 59 food protein panel in my clinic), and I consider it a crucial component of the healing process for many of my patients.
As per the old naturopathic proverb “It all comes back to the gut”.
In wellness,
James
