A method for testing, treating, and preventing delayed food allergies includes: receiving detailed symptom, medical, and dietary histories from a patient; formulating a combination of one or more food extracts at selected concentrations for sublingual administration over a trial period; determining whether the patient's symptoms have improved, worsened, or had no change, in response to the administration of the combination; and altering the combination in response to whether the patient's symptoms have improved, worsened, or not changed, so as to induce immune system food tolerance.