IgG and IgA food antibody testing is one of the most controversial tools in digestive medicine.

Some providers dismiss it entirely.

Others misuse it and create unnecessary fear around food.

Today I want to explain why this testing can be extremely helpful—and why it absolutely requires expert interpretation.

I’ve been treating IBS for over 25 years and founded the IBS Treatment Center in 2005, where we’ve helped more than 10,000 patients recover. I’ve run IgG and IgA testing on every single one of them so I know a few things about this kind of testing, and I’d to what I’ve learned with you.

Clearing up common misconceptions

You’ll often hear statements like:

“IgG just means you’ve eaten the food.”

“IgA only reflects mucosal immunity.”

Those explanations are incorrect and misleading.

IgG and IgA antibodies are active parts of the adaptive immune system.

They participate in immune signaling, inflammatory responses, and immune–antigen interactions.

And importantly, IgG and IgA antibody testing is already used in conventional medicine, including in celiac disease, where both IgA- and IgG-based antibodies play a central role in diagnosis and monitoring.

So the issue isn’t whether these antibodies are biologically meaningful.

The issue is how the information is interpreted.

Why This Testing Matters in IBS And Chronic Gut Symptoms

Many of the patients we see have already:

• Tried low FODMAP

• Done elimination diets

• Taken medications or supplements

• Been told “everything looks normal”

Yet they’re still symptomatic.

IgG and IgA testing help identify immune-mediated food reactions that don’t show up as classic IgE allergies.

There are controlled studies showing that IgG-guided elimination diets can improve IBS symptoms compared to sham diets. And I’ve included several of those below.

But more importantly, we’ve seen this clinically—thousands of times.

I’ve had patients who came in eating a very “clean” diet, doing everything right, but still reacting. When we used the right kind of antibody testing with a high quality and reproducible lab, we were able to identify patterns that finally explained why certain foods consistently triggered symptoms.

IgA Is More Than “Mucosal Immunity”

IgA does play a major role at mucosal surfaces—but clinically, it tells us more than that.

IgA patterns can reflect:

• Immune activation at the gut–immune interface

• Impaired tolerance to antigens

• Ongoing inflammatory signaling

In patients with long-standing IBS, autoimmunity, or chronic gut inflammation, IgA results can provide important context—especially when interpreted alongside symptoms and history.

The Critical Factor Almost Everyone Misses: Inflammation and Permeability

This is one of the most important points in this entire conversation.

If someone has significant gut inflammation or increased intestinal permeability, their immune system may be exposed to far more food antigens than normal.

When that happens:

• IgG and IgA baseline levels can rise

• Many foods may test positive

• And it can look like everything is a problem

I’ve seen patients come in with pages of “positive” foods and assume they’re intolerant to all of them.

In reality, there was another underlying issue responsible for their inflammation.

Once that was addressed, many of those foods were no longer a problem and the antibody levels dropped. In others only certain foods were the relevant triggers of their inflammation.

The test wasn’t wrong.

The interpretation just wasn’t complete.

Reintroduction: Sometimes Yes, Sometimes No

Here’s something I want to be very clear about:

Sometimes foods can be reintroduced.

And sometimes they can’t.

It depends on:

• The type of immune reaction

• The severity of the response

• And why the reaction is happening in the first place

I’ve worked with patients who were eventually able to reintroduce foods they hadn’t tolerated in years.

And I’ve worked with others where certain foods remained a problem—and avoiding them was the right long-term choice for staying symptom free.

This is why blanket statements don’t work.

There is no universal rule.

Why Expertise Matters More Than the Test Itself

IgG and IgA food antibody testing is not a DIY tool.

Without proper interpretation, it can:

• Lead to over-restriction

• Create fear around food

• And completely miss the real issue

At the IBS Treatment Center, we use this testing as one piece of a much larger clinical picture.

We look at:

• Patterns, not isolated numbers

• Symptoms, not just lab results

• And how to use the information strategically

That level of nuance comes from experience—decades of it.

If you’re struggling with these issues, there is more than hope. For over 20 years we’ve been working with people all over the world via telemedicine, and we’d love to work with you too.

And remember to take good care of your body—it’s the only place you have to live.

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