Food sensitivity testing has become increasingly popular, with many seeking to identify dietary triggers for symptoms such as bloating, fatigue, brain fog, migraines, and skin issues.
One of the most commonly used methods is IgG food sensitivity testing, which measures Immunoglobulin G (IgG) antibodies in response to various foods. However, based on current scientific evidence and expert recommendations, IgG testing is not considered a reliable tool for identifying food allergies or sensitivities. In fact, it may often lead to unnecessary dietary restrictions that can harm both physical and psychological health.
Understanding IgG and Its Role in the Immune System
IgG antibodies are a normal part of the immune system, reflecting exposure to specific foods. However, the presence of IgG antibodies does not necessarily indicate an intolerance or sensitivity. In fact, elevated IgG levels can indicate immune tolerance, meaning the body has become accustomed to certain foods. This is particularly true for IgG4 antibodies, which are associated with tolerance rather than allergy.
Food allergens can enter the immune system through several pathways in the gut, where the immune system decides whether to react. If the mucosal barrier is compromised, allergens are more likely to pass through and trigger an immune response. However, IgG antibodies are not responsible for the immediate allergic reactions that are commonly linked with food allergies.
- IgE antibodies: The key players in triggering these types of reactions, which can lead to symptoms like hives, swelling, or difficulty breathing.
- IgG antibodies: They are more related to food exposure rather than food intolerance.
The Scientific Consensus on IgG Testing
Many leading medical organizations, including the American Academy of Allergy, Asthma, and Immunology (AAAAI), the European Academy of Allergy and Clinical Immunology (EAACI), and the Canadian Society of Allergy and Clinical Immunology (CSACI), do not support the use of IgG testing for diagnosing food allergies. This is due to a lack of robust, high-quality research linking IgG levels to food sensitivities or intolerances.
Moreover, IgG testing often results in confusion. Since the tests may show sensitivity to common foods such as dairy, wheat, yeast or eggs, patients may be encouraged to eliminate multiple foods unnecessarily. These are common food intolerances that many individuals can identify through trial and error without the need for testing. However, when IgG tests suggest sensitivities to these foods, patients might eliminate them based on test results alone. Without professional guidance, such dietary restrictions can lead to nutritional deficiencies and make it difficult to maintain a balanced diet.
Risks of Unnecessary Dietary Restrictions
One of the main concerns with IgG testing is the potential for unnecessary and harmful dietary restrictions. Elimination diets based on IgG test results, especially when they are not guided by a healthcare professional, can lead to nutritional imbalances. Restricting certain foods without proper guidance can also contribute to disordered eating habits, psychological stress, and a negative relationship with food.
Food elimination diets are often unsustainable in the long-term. The removal of IgG-positive foods without reintroducing them fails to reflect typical dietary habits and can make it challenging to maintain a varied and balanced diet.
What the Research Shows About IgG Testing in Specific Conditions
IgG testing has been explored in various health conditions, but the results remain inconsistent. For example, some studies suggest that eliminating specific foods based on IgG test results may reduce the frequency of migraines. However, the clinical significance of these findings is unclear, as the studies had small sample sizes and often showed overlap between common migraine triggers and IgG-positive foods.
In the case of irritable bowel syndrome (IBS), while IgG levels may be higher, there is no consistent correlation between IgG levels and disease severity.2 This highlights the limited clinical application of IgG testing in gastrointestinal disorders. Studies conducted on IBS patients often identify common high-FODMAP foods as food intolerances – such as cashews, peas, corn, milk, and wheat – and have been limited by small sample sizes, poor patient compliance, and high dropout rates.
Alternative Approaches for Identifying Food Triggers
For individuals seeking clarity on food-related symptoms, evidence-based approaches tend to be more reliable. These include:
- A thorough dietary and symptom history: Reviewing patterns in food intake and symptoms can offer valuable insights.
- Elimination and reintroduction diets: Temporarily avoiding suspected foods and systematically reintroducing them can help identify triggers in a structured manner.
- Validated medical tests: For individuals with suspected allergies, tests such as IgE-mediated allergy testing or hydrogen breath testing for conditions like lactose intolerance may provide more accurate results.
The Bottom Line
While IgG food sensitivity testing is widely available, its clinical usefulness remains uncertain, and it is not supported by current scientific evidence. Rather than relying on IgG testing, a more comprehensive approach, incorporating medical history, dietary evaluation, and validated testing methods, tends to be more effective in addressing food-related symptoms.
If you are experiencing digestive issues or suspect food sensitivities, it is important to work with a healthcare provider who can help you create a personalized, evidence-based plan for identifying and managing food triggers. This approach will promote a balanced, healthy relationship with food and reduce the risk of unnecessary dietary restrictions that could negatively impact your health.
A Note on Individual Preferences and Rare Use Cases
Despite the current consensus and limitations surrounding IgG testing, we recognize that in rare and specific instances, some patients may still express a strong desire to explore this type of testing. In such cases, and after a thorough discussion of the current evidence, potential risks, and limitations, IgG testing may be considered as part of a broader, patient-centered approach. It is essential that this decision be made collaboratively.
Clinician Perspective
Based on our experience, the patients that have the highest levels of food sensitivities listed on their IgG food tests are the ones that have inflammation in their gut and therefore are mounting low grade sensitivities against the most common foods that they consume.
We often see the same foods come up as flagged on everyone’s test. For example, it is rare to see an IgG test without wheat, dairy, soy, nuts etc come up as a sensitivity, which does not mean that those people are allergic to those foods – it tells us that we need to work on their gut health.
In the case of more complex gut issues we often rely more on comprehensive stool testing such as microbiome mapping or SIBO testing.
While IgG food sensitivity testing continues to gain popularity, the current scientific evidence does not support its reliability for diagnosing food intolerances or guiding dietary decisions. Instead, a personalized, evidence-based approach, focused on medical history, symptom tracking, and validated testing, is more effective and sustainable. By working with a qualified healthcare provider, individuals can identify true food triggers, support gut health and maintain a balanced relationship with food without falling into the trap of unnecessary dietary restrictions.
References
Gocki J, Bartuzi Z. Role of immunoglobulin G antibodies in diagnosis of food allergy. Advances in Dermatology and Allergology/Postȩpy Dermatologii i Alergologii. 2016;33(4):253.
Bock SA. AAAAI support of the EAACI Position Paper on IgG4. The Journal of allergy and clinical immunology. 2010;125(6). doi:10.1016/j.jaci.2010.03.013
Carr S, Chan E, Lavine E, Moote W. CSACI Position statement on the testing of food-specific IgG. Allergy, Asthma & Clinical Immunology. 2012;8(1):1-2.
Fitzgerald M, Frankum B. Food avoidance and restriction in adults: a cross-sectional pilot study comparing patients from an immunology clinic to a general practice. Journal of Eating Disorders. 2017;5(1):1-12.
Alpay K, Ertaş M, Orhan EK, Üstay DK, Lieners C, Baykan B. Diet restriction in migraine, based on IgG against foods: A clinical double-blind, randomised, cross-over trial. Cephalalgia. 2010;30(7):829.
Atkinson W, Sheldon TA, Shaath N, Whorwell PJ. Food elimination based on IgG antibodies in irritable bowel syndrome: a randomised controlled trial. Gut. 2004;53(10):1459.
Staudacher HM, Shin A. Randomized Trial on Dietary Elimination Based on IBS-Specific IgG Testing: Has the Evidence for Food Sensitivity Arrived? Gastroenterology. Published online February 25, 2025. doi:10.1053/j.gastro.2025.02.012
