Does elevated IgG to a food mean the patient is allergic to it?

No. IgG to foods is found in healthy individuals and reflects normal exposure. Major allergy societies do not recommend IgG testing for food allergy or intolerance. In functional practice, elevated IgG identifies candidate foods for elimination trials, not confirmed allergens.

Why order a vegetarian-specific food panel?

The vegetarian panel is tailored for patients following plant-based diets and includes grains, legumes, nuts, seeds, vegetables, fruits, herbs, and spices while excluding animal products. It simplifies elimination protocols when animal foods are not relevant to the patient's diet.

Should the patient avoid suspect foods before testing?

No. The patient should be consuming their usual diet in the weeks before testing, because recent avoidance of a food can lower antibody levels and produce false-negative results. The test measures immune response to current dietary exposure.

Is fasting required for the test?

No. Fasting is not required for food-antibody testing, though the patient should continue their normal diet to ensure accurate representation of dietary exposure.

What is selective IgA deficiency and why does it matter?

Selective IgA deficiency is a common immunodeficiency in which serum IgA is very low or absent. It will cause uniformly low or absent food-specific IgA results, making the IgA portion of the panel uninterpretable. Total serum IgA should be measured concurrently to detect this condition.

Can this test diagnose coeliac disease?

No. Coeliac disease requires specific serology (tissue transglutaminase IgA, endomysial antibodies) and, if positive, duodenal biopsy. A food-sensitivity panel may show reactivity to gluten-containing grains but is not a substitute for coeliac testing, which must be done on a gluten-containing diet.

How should practitioners use the results?

Elevated antibodies identify candidate foods for a time-limited elimination trial (4–6 weeks), prioritising high-titre and frequently consumed foods. Symptoms are monitored during elimination and systematic reintroduction. Long-term avoidance should be based on documented symptom improvement, not antibody levels alone.

Why is this test controversial?

Major allergy societies state that IgG to foods reflects exposure, not intolerance, and recommend against its use. The test is not validated for diagnosing food allergy or intolerance. In functional medicine it is interpreted as a hypothesis-generating tool for elimination trials, not a diagnostic endpoint, and requires careful shared decision-making.

BML-FSA-016food sensitivity allergyUSA

198 Vegetarian Food Panel: IgA/IgG

Q: What is the difference between IgA and IgG food antibodies?

IgA is the mucosal antibody class and is thought to reflect recent intestinal exposure to a food antigen, while IgG is the most abundant circulating antibody and is widely considered a marker of dietary exposure rather than intolerance. Both are measured in functional food-sensitivity panels, but neither is diagnostic of food allergy or intolerance.

The 198 Vegetarian Food Panel measures serum IgA and IgG antibodies to 198 plant-based foods. It is a functional tool used in integrative practice to guide elimination trials in patients with chronic unexplained symptoms attributed to food. Elevated antibodies reflect immune exposure, not proven intolerance, and results must be interpreted with clinical correlation and caution.

Biomarkers

Blood (serum)

Sample

10–14 business days

Turnaround

Fasting

What is the 198 Vegetarian Food Panel test?

The 198 Vegetarian Food Panel measures serum IgA and IgG antibodies against 198 plant-based foods, grains, legumes, nuts, seeds, herbs, spices, and food additives. It is ordered in the evaluation of suspected non-IgE, non-coeliac food sensitivity — the clinical syndrome of chronic, non-specific symptoms (gastrointestinal distress, headache, fatigue, skin changes, joint pain) attributed to food but without evidence of classical allergy or coeliac disease. This panel is a functional-medicine tool, not a diagnostic test. Elevated IgA or IgG to a food does not prove the food causes symptoms, and reactivity is common in asymptomatic individuals. Practitioners order the panel to generate hypotheses for structured elimination-and-rechallenge trials in patients whose symptoms have resisted first-line investigation. The vegetarian panel is selected when the patient follows a plant-based diet or when eliminating animal products simplifies the elimination protocol. Interpretation requires clinical correlation and shared decision-making about trial exclusions.

What does the 198 Vegetarian Food Panel test measure?

IgA(Food-Specific Immunoglobulin A)

Range: Laboratory-specific interpretive thresholds; typically <1.0 = normal, 1.0–2.9 = borderline, ≥3.0 = elevated reactivity.Optimal: No validated 'optimal' range exists; reactivity is interpreted in the clinical context of symptoms and response to elimination.Arbitrary Units (AU) / Optical Density (OD)

IgA is the predominant antibody class in mucosal secretions and the first line of adaptive immune defence at the intestinal epithelium. Secretory IgA binds intraluminal antigens, preventing their adherence to and penetration across the mucosa. Serum IgA to food proteins is thought to reflect recent or ongoing mucosal exposure, though the relationship between circulating and secretory IgA is complex and the clinical meaning of serum food-specific IgA outside coeliac disease remains debated.

Food-specific IgA is measured in the context of non-coeliac food sensitivity, where it is proposed to reflect mucosal immune activation or barrier dysfunction. Elevated IgA reactivity to a food may signal heightened mucosal exposure rather than allergy, and interpretation is functional rather than diagnostic — it guides elimination trials in symptomatic patients, not definitive exclusion of foods in the absence of symptoms.

IgG(Food-Specific Immunoglobulin G)

Range: Laboratory-specific interpretive thresholds; typically <1.0 = normal, 1.0–2.9 = borderline, ≥3.0 = elevated reactivity.Optimal: No validated 'optimal' range; the presence of IgG to a food does not establish causation of symptoms and must be correlated clinically.Arbitrary Units (AU) / Optical Density (OD)

IgG is the most abundant circulating antibody and participates in memory responses to chronic or repeated antigen exposure. Food-specific IgG is found in healthy individuals without food intolerance and is widely considered a marker of dietary exposure rather than pathology. The mechanism by which IgG might drive symptoms in food sensitivity is unproven, and the class is not involved in classic IgE-mediated food allergy.

Measurement of food-specific IgG is controversial. Major allergy societies state that IgG to foods reflects exposure, not intolerance, and recommend against its use for diagnosing food allergy or intolerance. In functional and integrative practice, however, IgG is interpreted as one tool for identifying candidate foods for elimination trials in patients with chronic, otherwise unexplained symptoms — the test result prompts an experiment, not a diagnosis.

Why is the 198 Vegetarian Food Panel test ordered?

Investigation of chronic gastrointestinal symptoms (bloating, altered bowel habit, abdominal discomfort) that have not responded to standard therapy and in whom coeliac disease and inflammatory bowel disease have been excluded
Evaluation of recurrent or persistent dermatological conditions (eczema, urticaria, pruritus) without identifiable trigger, where dietary factors are suspected
Assessment of unexplained chronic fatigue, brain fog, or joint pain in the context of a suspected dietary trigger, after other causes have been addressed
Guidance for elimination diets in patients following vegetarian or vegan dietary patterns, where animal-based panels are less relevant
Support for patients with irritable bowel syndrome or functional gastrointestinal disorders considering a structured dietary trial beyond FODMAPs
Exploration of food triggers in patients with autoimmune or inflammatory conditions seeking adjunctive dietary management, interpreted with caution
Baseline assessment before and monitoring after a therapeutic elimination protocol, to observe changes in antibody patterns over time
Patients with multiple chemical sensitivity or systemic inflammatory symptoms attributing their condition to diet, where structured guidance is needed

Sample collection and turnaround

Sample type

Blood (serum)

Fasting required

Collection method

Venipuncture at patient service centre

Turnaround

10–14 business days

Collection notes

Phlebotomy required; specimen is sent to US BioTek for analysis. The patient should be consuming their usual vegetarian or plant-based diet in the weeks before testing, as recent avoidance of a food may lower antibody levels and yield false-negative results. Measure total serum IgA concurrently to detect selective IgA deficiency, which will confound interpretation of food-specific IgA.

Specimen requirements

Minimum 5 mL serum in a red-top or serum separator tube. Separate serum promptly and freeze if shipment is delayed. Specimen stability and shipping instructions are provided by US BioTek; follow cold-chain requirements.

What can affect 198 Vegetarian Food Panel results?

elevatesRecent or current consumption of the tested foods

IgA and especially IgG to foods can reflect normal dietary exposure; antibodies are higher to foods regularly consumed, so the panel often identifies staples rather than triggers.

elevatesIntestinal permeability and mucosal inflammation

Increased gut permeability from infection, dysbiosis, or inflammatory bowel disease permits greater antigen translocation, raising antibody responses to many foods non-specifically.

reducesImmunoglobulin deficiency (selective IgA deficiency)

Patients with selective IgA deficiency will have absent or very low food-specific IgA; the deficiency should be screened for with total IgA before interpreting food-IgA results.

variableRecent gastrointestinal infection or use of antibiotics

Acute infection or antibiotic-associated dysbiosis can transiently alter mucosal immune responses and antibody patterns, confounding interpretation.

reducesImmunosuppressive therapy or corticosteroids

Systemic immunosuppression blunts antibody production, potentially lowering measured food-specific IgA and IgG and masking true reactivity.

variableLaboratory assay variation and lack of standardisation

Food-antibody assays are not standardised across laboratories; reference ranges, antigen sources, and interpretive cut-offs differ, so results are not directly comparable between platforms.

What do 198 Vegetarian Food Panel results mean?

Elevated

Elevated IgA or IgG to a food indicates immune recognition of that food protein but does not prove the food causes symptoms. IgG elevation is common in healthy individuals and reflects exposure. IgA elevation may reflect mucosal exposure or barrier dysfunction. In symptomatic patients, elevated antibodies identify candidate foods for a time-limited elimination trial (typically 4–6 weeks), followed by systematic reintroduction and symptom monitoring. Multiple elevated reactivities are common; prioritise the highest-titre foods and those the patient consumes frequently. A positive result is a hypothesis, not a diagnosis.

Normal

Normal or borderline reactivity to a food does not exclude it as a trigger, particularly if IgE-mediated allergy or non-immune mechanisms (histamine, salicylates, FODMAPs) are involved. Conversely, normal results across the panel suggest that IgA/IgG-mediated food sensitivity is unlikely and that symptoms warrant investigation of other causes (small intestinal bacterial overgrowth, bile-acid malabsorption, mast-cell activation, anxiety-related gut dysfunction).

Reduced

Absent or low reactivity across the panel suggests the patient has not recently consumed those foods, has low antigen exposure due to barrier integrity, or (for IgA) may have selective IgA deficiency. Low reactivity does not exclude food sensitivity if the offending food was not tested or if the mechanism is non-immunological (enzyme deficiency, pharmacological reaction, FODMAP intolerance). Confirm total serum IgA if IgA reactivities are uniformly low.

Note: This test is not validated for diagnosing food allergy or intolerance and is not endorsed by major allergy societies. It is a functional tool for guiding elimination trials, not a stand-alone diagnostic. Results must be interpreted in the clinical context of symptoms, dietary history, and response to elimination. Do not advise long-term avoidance based solely on antibody reactivity without documented symptom improvement. Total IgA should be measured concurrently to detect selective deficiency. Serial testing after elimination may show falling titres but does not itself confirm clinical benefit.

Frequently asked questions

IgA is the mucosal antibody class and is thought to reflect recent intestinal exposure to a food antigen, while IgG is the most abundant circulating antibody and is widely considered a marker of dietary exposure rather than intolerance. Both are measured in functional food-sensitivity panels, but neither is diagnostic of food allergy or intolerance.

How to access the 198 Vegetarian Food Panel test

The 198 Vegetarian Food Panel 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:

Stapel SO, et al. Testing for IgG4 against foods is not recommended as a diagnostic tool: EAACI Task Force Report. Allergy. (2008)
Carr S, et al. CSACI position statement on the testing of food-specific IgG. Allergy Asthma Clin Immunol. (2012)
Gocki J, Bartuzi Z. Role of immunoglobulin G antibodies in diagnosis of food allergy. Postepy Dermatol Alergol. (2016)
Ligaarden SC, et al. IgG and IgG4 antibodies in subjects with irritable bowel syndrome: a case control study in the general population. BMC Gastroenterol. (2012)
Gunnarsson PT, et al. Food-specific serum IgG antibodies in healthy children and adults: correlation with age, sex, and food-specific serum IgE. Int Arch Allergy Immunol. (2013)

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.