IgG-associated Food Intolerances

Even in healthy individuals, food-specific IgG antibodies are physiologically produced. These IgG antibodies, ideally only detectable in small amounts in the blood, reflect the ongoing immunological interaction of the body with foreign antigens – including those found in food – and are therefore not considered to have any pathological significance.

However, elevated IgG concentrations in the blood are a consequence of increased exposure to food proteins that cross the mucosal barrier and enter circulation more easily. Especially the loss of mucosal integrity underlying the so-called "leaky gut" syndrome promotes increased production of food-specific IgG antibodies. Various external factors can disrupt intestinal barrier permeability and lead to greater translocation of partially digested food antigens into the bloodstream:

• Intestinal infections
• Microbial dysbiosis
• Use of medications
• Consumption of certain foods (e.g. gluten, alcohol, spicy seasonings)
• Exposure to environmental toxins (e.g. heavy metals, xenoestrogens such as bisphenol A, pesticides)

Patients with chronic inflammatory intestinal diseases such as Crohn’s disease or ulcerative colitis often show significantly elevated food-specific IgG titres due to immune system dysregulation. A subclinical inflammatory condition ("silent inflammation") – as seen in irritable bowel syndrome, metabolic syndrome (obesity), or depression – may also correlate with markedly increased IgG production against food antigens.

The range of possible symptoms is broad. The following ones may occur:

• Gastrointestinal complaints (e.g. diarrhoea, flatulence, irritable bowel syndrome)
• Dermatoses (psoriasis, eczema)
• Headaches/migraine
• Attention deficit/fatigue
• Depression/chronic fatigue syndrome
• Obesity/type II diabetes
• Cardiovascular diseases

In most cases, symptoms are delayed (up to 72 hours after eating) or persist chronically. Because of this delay, it is usually difficult to link the symptoms to specific foods during dietary history-taking. Therefore, the selective detection of elevated IgG antibody titres is a valuable diagnostic tool for identifying foods that may trigger an IgG-associated intolerance.

A diagnosis of IgG-associated food intolerance based on positive IgG findings should be verified and confirmed through an IgG-guided elimination or exclusion diet. This involves strictly avoiding foods for which significantly elevated IgG titres have been detected, for a set period of time. During the subsequent provocation phase, selected excluded foods are gradually reintroduced. Foods that cause symptoms again upon reintroduction should be avoided in the long term.

To assess IgG-associated food intolerance, MVZ GANZIMMUN GmbH has developed a tiered diagnostic approach for the analysis of food-specific IgG antibodies in serum. As an initial step, a preliminary screening (PreScreen IgG, PreScreen Allergy) tests a limited but meaningful selection of foods to determine IgG levels. A calculated PreScreen Index helps determine whether more extensive follow-up diagnostics are indicated. Several extended test profiles are available (Allergo-Screen® Basic, Allergo-Screen® Veggie, Allergo-Screen® Premium), which differ in the number and classification of foods tested.