Food intolerance testing (based on IgG antibodies) is a serological test that measures the level of immunoglobulin G (IgG) antibodies specific to antigens in a wide range of foods. The proposed mechanism of intolerance differs from that of traditional food allergy (IgE). The theory suggests that a delayed IgG-mediated immune response may contribute to low-grade inflammation and nonspecific symptoms upon repeated consumption of certain foods. It is important to note that this test is controversial, and many major medical associations for allergy and gastroenterology do not recognize it as an evidence-based diagnostic tool for food intolerance.