Blood tests measure the presence of IgE antibodies to specific foods. IgE, is the immunoglobulin E, which is the antibody that triggers food allergy symptoms. Food Intolerance (Blood) is a test that determines specific immune system-based food intolerances. The food we eat can bring forth a positive or negative reaction in the body. Food Intolerance test is a proven method that doctor and pharmacist s recommend which is a IgG-related test that assesses which foods are causing negative reactions.