IgG-mediated food sensitivity reactions are delayed, taking hours or days to appear after ingesting the offending food. Unlike immediate IgE-mediated food allergies, IgG sensitivities are difficult to detect without specialized testing and can involve multiple foods. Symptoms of IgG food sensitivity can affect any tissue or organ and include conditions like irritable bowel syndrome, asthma, and behavioral issues in children. Testing for IgG antibodies to specific foods can help identify sensitivities and guide elimination diets to improve conditions like rheumatoid arthritis and autism.