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96 IgG Gastrointestinal Portfolio

The 96 IgG Gastrointestinal Portfolio measures serum immunoglobulin G antibodies to 96 foods and additives, used in functional medicine to identify candidate foods for supervised elimination trials in patients with chronic gastrointestinal or systemic symptoms. It is an exploratory, non-diagnostic tool not endorsed by mainstream guidelines for food intolerance diagnosis.

1

Biomarkers

Blood (serum)

Sample

7–10 business days

Turnaround

No

Fasting

What is the 96 IgG GI Portfolio test?

The 96 IgG Gastrointestinal Portfolio quantifies serum immunoglobulin G antibodies to a comprehensive panel of 96 foods, beverages, and additives frequently implicated in gastrointestinal and systemic symptoms. It is ordered in functional and integrative medicine settings as an exploratory screen to identify foods that may be contributing to chronic, unexplained symptoms in patients who have not responded to conventional dietary or pharmacological interventions. The test does not diagnose food allergy — IgE testing, oral food challenges, and clinical history remain the gold standard for true allergy — and food-specific IgG is not recognised by mainstream allergy or gastroenterology guidelines as a standalone diagnostic for intolerance. Instead, practitioners use elevated IgG results to prioritise foods for supervised elimination-rechallenge trials, integrating the laboratory data with symptom diaries, dietary history, and nutritional assessment. The goal is hypothesis generation rather than definitive diagnosis, and any elimination diet derived from IgG results must be time-limited, nutritionally balanced, and followed by systematic reintroduction to establish genuine clinical reactivity.

What does the 96 IgG GI Portfolio test measure?

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IgG(Immunoglobulin G Food-Specific Antibodies)
Range: Laboratory-specific thresholds classify foods as normal, borderline, or elevated reactivity; typically <3.0–3.5 AU is normal, 3.5–8.0 borderline, >8.0 elevated.Optimal: No universal 'optimal' range exists. Individual foods with elevated IgG (typically >8.0 AU on this platform) are candidates for supervised elimination trials, but the threshold for clinical action depends on symptom correlation, dietary diversity, and nutritional risk; a result within the laboratory normal range does not exclude intolerance mediated by other mechanisms (IgE, cell-mediated, enzymatic).Arbitrary units (AU) / U/mL

Immunoglobulin G is the most abundant circulating antibody, mediating delayed immune responses through Fc-receptor binding and complement activation. Food-specific IgG antibodies form when dietary proteins cross the intestinal barrier and trigger an adaptive immune response. Their presence indicates prior antigen exposure and immune recognition but does not, in isolation, prove food intolerance or allergy; healthy individuals eating diverse diets routinely develop IgG to commonly consumed foods without clinical symptoms. The clinical relevance of elevated IgG to individual foods remains contested, with mechanistic debate over whether such antibodies reflect tolerance, normal exposure, increased gut permeability, or a pathogenic driver of inflammation.

This panel quantifies IgG antibodies to 96 gastrointestinal-relevant foods, beverages, and food additives. Proponents of IgG-guided elimination diets report symptomatic improvement in subsets of patients with irritable bowel syndrome, migraine, and non-coeliac gluten sensitivity, hypothesising that elevated IgG marks foods driving low-grade inflammation or immune activation. Critics note that food-specific IgG is a marker of exposure rather than causation, that numerous controlled trials have failed to validate IgG-guided elimination for most conditions, and that removing many foods risks nutritional deficiency and disordered eating. Mainstream gastroenterology and allergy societies do not endorse routine IgG food testing for diagnosis of food allergy or intolerance, reserving IgE testing and supervised elimination-rechallenge for confirmed allergy work-up. The test is positioned as an exploratory functional tool to identify candidate foods for supervised trial elimination in patients with chronic gastrointestinal or systemic symptoms refractory to standard care, always integrated with clinical history, symptom diaries, and dietetic oversight.

Why is the 96 IgG GI Portfolio test ordered?

  • Patients with chronic unexplained gastrointestinal symptoms — bloating, altered bowel habit, abdominal discomfort — refractory to standard irritable bowel syndrome management and after exclusion of coeliac disease and inflammatory bowel disease
  • Evaluation of suspected non-IgE-mediated food reactivity in individuals reporting delayed or systemic symptoms (fatigue, headache, joint discomfort, skin changes) temporally associated with eating but with negative IgE allergy testing
  • Functional assessment in chronic migraine or tension-type headache when dietary triggers are suspected and conventional trigger avoidance has been incomplete or unhelpful
  • Exploration of food-immune interactions in patients with suspected increased intestinal permeability or dysbiosis, particularly when other gastrointestinal and immune markers are already being evaluated
  • Personalised nutrition planning in integrative or functional medicine practice, where the clinician and patient elect to use IgG data as one input among many to trial a supervised elimination protocol
  • Monitoring dietary antigen exposure in patients who have previously completed an elimination diet and are reintroducing foods, to correlate IgG trends with symptom changes over time

Sample collection and turnaround

Sample type

Blood (serum)

Fasting required

No

Collection method

Venipuncture at patient service centre

Turnaround

7–10 business days

Collection notes

Phlebotomy at a patient service centre; specimen is sent to Alletess Medical Laboratory for analysis. No fasting required. Ideally the patient should be eating their usual diet for at least two weeks before testing, since IgG reflects recent antigen exposure; elimination or rotation diets immediately prior to the test may reduce antibody levels and yield false-negative results.

Specimen requirements

Serum separator tube; minimum volume per Alletess protocol (typically 5–7 mL whole blood to yield adequate serum). Separate serum promptly and ship refrigerated or frozen per laboratory instructions.

What can affect 96 IgG GI Portfolio results?

elevatesRecent dietary exposure and frequency of consumption

IgG to a food typically reflects regular consumption and antigen exposure; elevated IgG may simply mark a staple food rather than an intolerance, so dietary history is essential to interpretation.

reducesPrimary or secondary immunodeficiency

Patients with hypogammaglobulinaemia or selective IgG subclass deficiency produce blunted antibody responses, so low or absent food-specific IgG does not exclude reactivity if total IgG is low.

elevatesIntestinal permeability and gut inflammation

Increased gut barrier permeability allows more dietary antigens to reach the immune system, potentially raising IgG to multiple foods; the pattern may reflect barrier dysfunction rather than individual food pathogenicity.

variableRecent infection or immune activation

Acute illness and polyclonal B-cell activation can transiently alter antibody levels; testing during active infection or shortly after may not reflect baseline reactivity.

reducesImmunosuppressive or immunomodulatory therapy

Corticosteroids, biologics, and other immune-suppressing drugs can dampen IgG production, leading to falsely low food-specific antibodies and underestimation of reactivity.

elevatesCross-reactivity between structurally similar food proteins

Antibodies raised against one food may bind related proteins in another (for example, tree nuts, or cereal grains), producing elevated IgG to multiple foods within a family and complicating interpretation of which specific food is clinically relevant.

What do 96 IgG GI Portfolio results mean?

Elevated

Elevated IgG (typically >8.0 AU on this platform) to one or more foods indicates immune recognition and prior exposure. It is not diagnostic of intolerance but identifies candidate foods for a supervised elimination trial lasting 4–6 weeks, followed by systematic rechallenge. If symptoms improve during elimination and reproducibly return on rechallenge, clinical reactivity is probable. Many healthy individuals show elevated IgG to commonly eaten foods without symptoms, so correlation with clinical history and symptom diaries is essential.

Normal

IgG within the laboratory normal range (<3.0–3.5 AU) suggests no significant immune recognition of that food under current dietary conditions. It does not rule out intolerance by other pathways, and the test does not assess all possible food antigens or all immune mechanisms. A normal panel in a symptomatic patient warrants consideration of non-immune causes (fermentable carbohydrate intolerance, bile-acid malabsorption, visceral hypersensitivity, among others).

Reduced

Low or absent IgG to a food typically reflects lack of recent exposure (the food is not in the diet) or, rarely, an immunodeficiency. A normal or low IgG does not exclude intolerance mediated by IgE, cell-mediated immunity, enzymatic deficiency (lactose, fructose), or other non-IgG mechanisms, so clinical suspicion should guide further testing.

Note: This is an exploratory, non-diagnostic functional test. Mainstream guidelines from allergy and gastroenterology societies do not endorse IgG food panels for diagnosis of food allergy or intolerance. Results must be integrated with clinical history, dietetic assessment, and controlled elimination-rechallenge, never used in isolation to impose long-term restrictive diets. Any elimination should be time-limited, nutritionally adequate, and supervised to avoid deficiency and disordered eating. The arbitrary units and cut-offs are proprietary to Alletess and not interchangeable with other laboratories; serial monitoring should use the same platform.

Frequently asked questions

IgE mediates immediate allergic reactions — anaphylaxis, urticaria, acute gastrointestinal symptoms — and is the diagnostic gold standard for true food allergy. IgG reflects delayed immune recognition and prior exposure; elevated IgG is used in functional medicine to explore non-IgE intolerance, but it is not a marker of allergy and is not endorsed by mainstream allergy guidelines.

How to access the 96 IgG GI Portfolio test

The 96 IgG GI Portfolio reference page is free and open to all practitioners. Create a free practitioner account to see pricing, save tests to your list, and generate requisition forms. Verification takes 1–2 business days.

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About this page

Published: October 7, 2026

Last reviewed: October 7, 2026

References:
  1. Stapel SO, et al. Testing for IgG4 against foods is not recommended as a diagnostic tool: EAACI Task Force Report. Allergy. (2008)
  2. Carr S, et al. CSACI position statement on the testing of food-specific IgG. Allergy Asthma Clin Immunol. (2012)
  3. Guo H, et al. The value of eliminating foods according to food-specific immunoglobulin G antibodies in irritable bowel syndrome with diarrhoea. J Int Med Res. (2012)
  4. Atkinson W, et al. Food elimination based on IgG antibodies in irritable bowel syndrome: a randomised controlled trial. Gut. (2004)

This content is for licensed healthcare practitioners only and does not constitute medical advice. Clinical decisions should be based on the full clinical picture and not on any single test result.