Food sensitivity test: what IgG and IgE food tests can show

Allergy, sensitivity and intolerance

Why IgG food tests aren't diagnostic

IgG panels test your blood against a list of foods and flag the ones with high IgG. The problem is what IgG means. The American Academy of Allergy, Asthma and Immunology says IgG to a food is likely a normal response to eating it, and higher IgG4 may even be linked to tolerating the food.

• AAAAI says the test has never been scientifically proven to do what it reports to do.
• AAAAI and the Canadian Society of Allergy and Clinical Immunology both recommend against IgG testing to diagnose food allergy or intolerance.
• AAAAI advises getting advice from an allergist before making big diet changes.

If you have already taken one, high IgG mostly reflects foods you have been eating. It is not a diagnosis, but it can be a starting list for an elimination trial.

How root-cause practitioners use IgG panels

Many functional and integrative practitioners use an IgG panel as a map, not a verdict. They read it alongside your gut health, your symptoms and a food diary, then run an elimination and reintroduction trial. Gabriel uses IgG panels the same way. How you feel when a food comes back is the answer that counts.

• Treat flagged foods as candidates to test, not foods to avoid for good.
• Remove a few suspects for a few weeks, then add them back one at a time.
• Keep any food that causes no symptoms when it returns, so your diet stays varied.
• Work with a practitioner or dietitian if you are cutting several foods.

What IgE tests and food challenges show

IgE is the antibody behind true food allergy. Skin prick tests and IgE blood tests are sensitive, but they are often positive in people who can eat the food without trouble. A positive result shows sensitization, and an allergist reads it with your history.

The oral food challenge is the gold standard. You eat the food under the watch of an experienced clinician in a setting ready to handle a reaction. Don't try a food that has caused a reaction on your own to test it.

How an elimination diet works

1. Keep a food and symptom diary to spot patterns.
2. Remove one suspect food or group for a few weeks.
3. Add it back, one food at a time, and watch for symptoms.
4. If symptoms return when the food comes back, it may be an intolerance. Limit only what you need to and keep the rest of your diet balanced.

Some intolerances have real tests. A hydrogen breath test checks for lactose or fructose intolerance. Your clinician may also rule out celiac disease or a food allergy first. A dietitian can help so that cutting foods doesn't leave gaps in nutrition. Check with a clinician before cutting foods for a child or during pregnancy.

Call 911 for trouble breathing, throat or tongue swelling, wheezing, fainting or dizziness after eating. That can be anaphylaxis. See a clinician if digestive symptoms are severe or don't go away, since other conditions, such as celiac disease, can cause similar symptoms.