'I feel terrible after eating X, but my allergy test came back negative.' I hear this at least twice a week. The disconnect isn't surprising — food allergies and food sensitivities are genuinely different phenomena, tested differently, mediated by different immune mechanisms, and managed differently.
Food Allergy: The IgE Response
A true food allergy involves an IgE-mediated immune response — the same mechanism behind anaphylaxis. Symptoms appear within minutes. Standard allergy testing identifies IgE-mediated sensitivities only. If your panel is negative, it means your immune system isn't producing IgE antibodies — not that you're not reacting through other mechanisms.
Food Sensitivity: The IgG and Non-Immune Mechanisms
Food sensitivities are delayed, dose-dependent, and mechanistically diverse. They can involve IgG antibody responses, intestinal permeability issues, enzymatic deficiencies, or direct pharmacological effects of food compounds. Symptoms often emerge 2–72 hours after exposure, making them hard to connect causally to what you ate.
Common presentations include: bloating and gas, fatigue after eating, brain fog, headaches, joint pain, skin issues, and disrupted sleep. These symptoms overlap with many conditions — which is why food sensitivity often goes unidentified for years.
How We Test and What It Means
Food sensitivity testing at M Health uses IgG antibody panels to identify immune reactivity to 90–200+ foods. A positive result means there's a reactive relationship worth investigating. We use results to guide elimination and reintroduction protocols and support gut healing where appropriate. Testing is a starting point, not a verdict.
