IImmunoglobulin (Ig) G, A, and E are the three main types of antibodies that play important roles in the immune system, each with unique functions and locations within the body: Immunoglobulins (Ig) are antibodies produced by the immune system to fight off infections.
IgA neutralizes antibodies and supports mucous membranes. It is found in the
mucous membranes of the lungs, sinuses, stomach, and intestines.
IgG is the most common antibody in blood and other body fluids. It's a more delayed and potentially more mild immune response than IgE.
IgE are primarily associated with allergic reactions. It triggers mast cells to release chemical mediators that cause allergic reactions like coughing, sneezing, and vomiting
In other words, IgG operates mainly in the bloodstream, IgA protects mucosal surfaces, and IgE is primarily involved in allergic responses.
The body has many ways in which it can react negatively to foods, including mechanisms that don’t involve antibodies or measurable immune reactivity. Testing can be valuable for some but is not always necessary. Many times, people are already aware of the most likely culprits. The gold standard is food elimination and structured reintroduction. No single food allergy/sensitivity/intolerance panel is going to yield a comprehensive and fully accurate list of all foods that might be causing inflammation and/or discomfort.
Food intolerances such as lactose or fructose intolerance are not reactions from the immune system at all, but individuals with these intolerances will still suffer from consuming these foods. The body can also react to lectins, mycotoxins, chemical additives, and other triggers in food that will not show up on a typical food antibody panel.