I was looking at a website to a local dermatologist and this is what they said about testing for food
allergies: An important point to understand is that neither blood testing nor intradermal skin testing are useful for identifying allergy to foods. Although some companies offer blood tests for food allergy, we cannot promote their use. For the same reason, we do not offer skin testing for food allergy. Instead, we use specialized hypoallergenic diet trials containing novel or hydrolyzed ingredients.
My vet has also said that you cannot detect food
allergies through a blood test. This is discouraging to me but you said you have done it and it proved to be accurate.