Why I Stopped Running IgG Food Sensitivity Tests

This may be a controversial topic, but it’s an important one.

I am not a Naturopathic Doctor that runs food sensitivity testing. I used to do this at the beginning of my practice, and I no longer run these tests. I want to talk about why.

One of the most common reasons patients request food sensitivity testing is to identify potential triggers for digestive symptoms such as bloating and gas. When the root cause remains unclear, it’s natural to seek answers.

Let's first talk about what the food sensitivity test is. Food sensitivity tests assess IgG antibodies, which are different from IgE-mediated allergies.

IgE responses come from true food allergies, which can trigger immediate and potentially dangerous reactions like hives, swelling, or even anaphylaxis. These are the kinds of allergies where someone might need to carry an EpiPen.

On the other hand, IgG responses are not the same as allergies. They are often linked to delayed reactions and can sometimes indicate that your body has been exposed to a food and is actually tolerating it, rather than reacting negatively to it. This is why IgG food sensitivity tests can be misleading—just because a food is flagged doesn’t always mean it’s causing a problem.

When I was running this at the beginning of my practice, I noticed a few things that were alarming for me:

1. Many women restricted the foods from the “red” and “yellow” food groups for a much longer period of time, even if we discussed a reintroduction plan. Many were too scared to reintroduce foods back into the diet, out of fear of symptoms coming back or getting worse. This could also potentially trigger a relapse in an eating disorder. 

2. Nearly every test indicated gluten and dairy as problematic, which made me question the reliability and accuracy of these results.

3. Nutrient deficiencies were common with long-term restriction.

4. Some foods showed up on the testing and were not actually being consumed in the patient’s diet. The explanation provided by the lab companies is that these foods are cross reacting with other foods in the patient’s diet. This is confusing for everyone.

As with any clinician, when we know better, we do better. I always stand by this. 

I found it challenging to know that the foods flagged in the results might be clinically insignificant, as research suggests they are often normal findings in asymptomatic individuals.

For my patients, the goal is to enjoy as many foods as possible. This test was not in alignment with that goal. There are many psychological consequences and microbiome repercussions in running this test, full stop.

The cost will also range anywhere from $200-400 for the test. This is a barrier to many.

If through shared decision-making, I have any suspicions that there may be food aggravations, an empirical food elimination and reintroduction diet will serve the same purpose as the IgG food antibody test, to no extra cost for the patient.

Alternatively, if IBS (irritable bowel syndrome) is suspected, the low FODMAP diet is a clinically supported, evidence-based approach that can be followed for a short period (2-4 weeks) with a structured reintroduction plan, often leading to highly effective results.

Here’s an analogy that I can give regarding this test: Imagine a security system that sounds an alarm every time a shadow moves past your window—even if it’s just a tree branch swaying in the wind. The biomarker (IgG) being flagged is like that shadow: it might look suspicious, but it’s actually something completely normal and seen in healthy people. Now, if the response to every false alarm was to call in a SWAT team that could potentially damage your home, you’d start to wonder whether the system is truly helping or just creating unnecessary problems. Similarly, if the treatment for this flagged biomarker has risks, we need to ask: Are we treating a real threat, or just reacting to a normal, harmless signal?

To summarize: The IgG food antibody test is not clinically validated, and research suggests that these antibodies can be present in healthy individuals without causing any symptoms.

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