Thank you for your inquiry.
As you are well aware, the presence of specific IgE to a food does not mean that the food is causing symptoms upon ingestion. The only true test for food allergy is an oral challenge. Unfortunately, there are difficulties, as you might guess, in performing oral challenges to these many foods, especially when the endpoint is not a visible one (nausea and heartburn). There are so many other factors that might be considered as causes of nausea and heartburn that even a positive response would be difficult to interpret.
Nonetheless, to assess any definitive relationship between the ingestion of a particular food and the symptoms expressed, an oral challenge would be needed. Because nausea and heartburn can also be aggravated by psychological factors, a blinded food challenge would be the preferred technique. However, as noted, from a practical standpoint this would be difficult.
Another technique that is used to diagnose food allergy is a food diary, as you have already instituted. However, from personal experience, I do not think that will be an effective tool for you in this particular patient.
Empiric withdrawal of foods from the diet is the final technique that you could employ, and I think this would be easier and more effective than a food diary.
Finally, I believe this patient, if they have not seen a gastroenterologist, should do so. There are other diagnoses that clearly need to be considered, and the patient might benefit by an EGD with an esophageal biopsy.
Thank you again for your inquiry and we hope this response is helpful to you.
Phil Lieberman, M.D.