In an oral food challenge, small increment amounts of food are fed to the patient over a period of a few hours to determine if a reaction occurs. Due to the possibility of a severe reaction, it must be conducted under medical supervision by an experienced provider and in a facility with emergency medication and equipment on hand.
Food allergies can be challenging and stressful, so knowing what you or your child is eating is an important first step. If you have doubts about a possible food allergy, err on the side of caution until you have a chance to speak with your provider.
A blood test (commonly known as RAST) detects the presence of allergen-specific antibodies known as immunoglobulin E (IgE) antibodies. Additionally, a relatively new test, called a “component test” can be ordered to gain more specific information and is mostly used for peanut allergies. Blood tests have been used extensively but often are not specifically based on patients’ detailed diet diary. When not properly utilized, the results of a blood test can be very confusing and may lead to unnecessary food restriction. Allergists use their experience to determine when a blood test may be helpful and to properly interpret the results of the blood test.
There are a number of non-standardized tests that are advertised as helping diagnose food allergy. These tests include allergen-specific IgG blood tests, antigen leukocyte cellular antibody tests, hair analysis, and applied kinesiology. Their use in the diagnosis of food allergy is not advised.