Fatigue that lingers. Focus that slips. Inflammation with no clear origin. These symptoms show up in exam rooms daily—and often persist despite normal labs, clean diets, and well-structured protocols. or many, the underlying trigger may look like a hormone imbalance or nutrient gap when the root cause is a hidden immune reaction to food.
Unlike classic food allergies that cause immediate responses—like hives or airway swelling—delayed reactions, often mediated by IgG antibodies, can quietly impact gut health, hormone clearance, neurotransmitter production, and energy metabolism. Over time, this creates a persistent immune burden and chronic inflammation that standard treatments may miss.
As Candice Coleman Pope, NP and founder of TheWholeNP, explained in a recent Access Live webinar, “Food is more than fuel—it’s immunologic input.” When the immune system misidentifies food as a threat, even clean eating can backfire. Without the right testing protocols, these patterns often remain invisible, leaving both patients and providers guessing.
The immune system produces different antibodies—also called immunoglobulins—that recognize and neutralize bacteria, viruses, allergens, and food antigens. Understanding their functions helps clinicians interpret test results and identify the true source of immune reactivity.
| Antibody | Primary Role | Key Clinical Points |
| IgE | Immediate allergic reactions and parasite defense | Binds to mast cells and triggers histamine release (Type I hypersensitiveity). Classic allergy marker (e.g., peanuts, shellfish). |
| IgG | Long-term immunity and memory response | Most abundant in blood and extracellular fluid. Indicates past exposure and delayed hypersensitivity (Type III) - Half-life ~21 days |
| IgA | Mucosal immunity in the GI, respiratory, and urogenital tracts | Found in saliva, tears, breast milk, and gut secretions. Critical for gut lining protection. Low levels may reflect mucosal barrier dysfunction. |
| IgM | First antibody produced in acute immune response | Largest antibody (pentameric). Indicates recent infection or antigen exposure. Often elevated early in inflammation or food reactivity. |
| IgD | B cell signaling | Limited clinical utility. Primarily studied in research settings. |
Immune reactions to food don’t always follow the same script. Some are immediate and dramatic. Others are subtle and delayed—creating a low-grade inflammatory load over time. Understanding these two patterns helps clinicians interpret symptoms that otherwise seem disconnected.
When someone reacts to a food within minutes—think hives, shortness of breath, or swelling—that’s an IgE-mediated allergy. These are acute, histamine-driven responses that typically require strict avoidance.
IgG responses are more delayed—showing up 24 to 72 hours after exposure. Symptoms may include fatigue, bloating, skin flare-ups, or mood changes. These aren’t traditional “allergies” but immune reactions that contribute to systemic burden over time.
| Feature | IgE 🔴 | IgG 🔥 |
| Onset | Minutes to hours | 24–72+ hours |
| Mechanism | Type I hypersensitivity | Type III immune complex reaction |
| Symptoms | Hives, itching, airway swelling | Fatigue, brain fog, mood changes, joint pain |
| Clinical Insight | Classic allergy, requires lifelong avoidance | Delayed reactivity, may improve with gut repair |
| Use Case | Identify immediate food allergies | Identifying chronic immune triggers tied to metabolism and hormone imbalance |
“If the IGG panel lights up like a Christmas tree, I immediately evaluate the gut lining.”
- Candice Coleman-Pope, NP
View Complete foodANALYZER sample report.
Understanding the difference between IgE and IgG reactivity isn’t just academic—it’s actionable. Each response type has distinct effects on physiology, and when unaddressed, they can impact everything from hormone clearance to mental sharpness.
IgG-mediated food sensitivities often coincide with increased intestinal permeability (“leaky gut”). When the gut lining is compromised, food proteins cross into the bloodstream activating the immune system and triggering widespread inflammation. This ongoing reactivity becomes both a cause and consequence of further mucosal damage.
Inflammation doesn’t stay isolated in the gut—it affects liver detox pathways, adrenal function, and hormone signaling:
Since the gut plays a major role in producing serotonin and dopamine, inflammation here can show up as mood swings, anxiety, lack of focus, or low motivation. These symptoms are often mislabeled as mental health issues when they may be rooted in gut-immune dysfunction.
“The gut produces 90% of serotonin and 50% of dopamine. If food triggers are inflaming the gut, they’re also impacting the brain.”
- Candice Coleman-Pope, NP
Both IgE and IgG responses can interfere with metabolic flexibility:
Testing both IgE and IgG antibodies gives clinicians a broader perspective on immune activity and food reactivity. This dual approach helps to:
• Prioritize food eliminations with higher clinical relevance
• Target gut repair strategies more effectively.
• Support endocrine, metabolic, and cognitive recovery from the ground up
“I test, not guess. IgG antigens have a half-life of ~21 days. Without removing food for that long, you can’t be sure you're not reactive.”
- Candice Coleman-Pope, NP
[Related Content] GLP-1 and Gut Health: Addressing Metabolic Dysfunction
IgG tests for food sensitivities, like Access Medical Labs' foodAnalyzer panel offer clear advantages for clinicians working with complex cases:
These tools are especially useful for patients with:
Whether you're refining an elimination protocol, supporting hormone clearance, or rebuilding gut-brain resilience, IgE and IgG testing provides the data needed to move from guesswork to clarity.
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