An honest look at IgG food sensitivity testing — and what makes SiaScan different

If you've read about IgG food sensitivity tests online, you've seen the criticism. Major allergy and immunology bodies — including the AAAAI and the European Academy of Allergy and Clinical Immunology — have cautioned that conventional IgG food tests are not validated for diagnosing food allergy or intolerance. The core objection is simple: a standard IgG test measures how much antibody your immune system produces against a food, but IgG is largely a marker of exposure and tolerance, not pathology. Eating a food regularly can raise your IgG to it — without it causing you any harm.

We agree with that critique as it applies to conventional IgG testing. A single IgG quantity, read in isolation, tells you very little. That's exactly why SiaScan exists.

Antibodies aren't just on/off switches. Every IgG molecule carries sugar structures — glycans — attached to its Fc region. These sugars change how the antibody behaves: whether it ramps inflammation up or damps it down. The study of these sugar structures is called glycosylation, and it's one of the most active areas in immunology.

Decades of peer-reviewed research show that IgG glycosylation shifts in inflammatory and autoimmune states — rheumatoid arthritis, IBD, and other conditions all correlate with characteristic glycan patterns. In other words, the sugar on the antibody matters as much as the antibody itself.

Standard IgG tests ignore glycosylation entirely. They count antibodies and stop there. SiaScan looks at the glycan signature — the pattern that signals immune activation rather than mere exposure.

The difference is the difference between counting cars and reading their engine diagnostics. Quantity alone misleads; the functional state of the antibody is what carries signal.

The science underpinning SiaScan rests on two established bodies of literature:

1. IgG glycosylation in inflammation. A large body of peer-reviewed work demonstrates that IgG Fc glycosylation patterns shift in inflammatory disease, altering the antibody's effector function. This is the mechanistic basis for reading glycan signatures as immune-state signals rather than exposure counts.
2. Elimination diet methodology. The gold standard for identifying food sensitivities is structured elimination and blinded reintroduction — the same protocol SiaScan's tracking and validation tools are built around. The test points the way; the elimination-and-reintroduction confirms it.

A note on citations. We're compiling a public reference library of the glycosylation and elimination-diet literature. If you're a clinician and want the full bibliography, contact us and we'll share it.

Credibility means being clear about limits. SiaScan IgG is not:

• A food allergy test. IgE mediates true food allergy (anaphylaxis). SiaScan measures IgG, a different arm of the immune response. Never use it to assess anaphylactic risk.
• A medical diagnosis. It's an informational screening tool to guide dietary exploration, not a substitute for clinical evaluation.
• A standalone answer. A result is a hypothesis to test against how you actually feel — which is why we built the symptom-correlation lab.

We'd rather you trust us because we're honest about what we don't know than because we oversold what we do.

The single biggest weakness of conventional IgG testing is that it ends at the lab. You get a list of foods and a number, with no way to know whether any of it reflects your real life. That's the gap SiaScan's Symptom Correlation Lab closes.

Inside My Plate, you log what you eat and how you feel. The lab measures whether each IgG-flagged food actually tracks with your symptoms — confirming some triggers, showing others you may tolerate, and surfacing foods your body reacts to that the test didn't flag. The test proposes; your data confirms.