A 35-year-old man has psoriatic arthritis. After starting treatment with methotrexate, he seeks the opinion of a holistic care provider, who suggests testing for "food sensitivity" to identify any foods that may be contributing to his symptoms. The patient is provided with a test report, which suggests that cows' milk and dairy products, wheat, eggs and many other foods should be avoided. The patient is told that food intolerances may be heritable and that he should consider testing his healthy young daughter.
Case 2A four-year-old girl has flexural patches of pruritic skin since infancy, diagnosed as atopic dermatitis. Her mother is concerned about the safety of topical corticosteroids and limits their use. She visits a holistic care provider and is offered a blood test, described as "food allergy" testing, to identify any foods contributing to the child's eczema. After blood is drawn and analyzed, the test results highlight many foods the child should be avoiding, including eggs. The parents keep a vegetarian household, and the child does not eat any meat or fish. Eggs are a major component of the child's diet.