Testing for food intolerance: what works and what does not

You fill a tube with blood, send it off, and two weeks later you get a colourful report: avoid wheat, yeast, milk, egg and twenty other things. It looks scientific and you want an answer. But that is exactly where the problem lies. The best-known food intolerance test, the IgG blood test, measures something very different from what the seller leads you to believe.

Honestly: I find the IgG food test one of the most misleading products in this corner. Nice reports, little evidence, and the risk that you needlessly restrict your diet.

Which food intolerance tests are reliable?

The difference between a useful and a useless test comes down to one question: does it measure a real, treatable condition? The table below is your decision aid.

Celiac disease and lactose intolerance belong to the group with validated tests, because the result says something about a real condition. Read about the difference in gluten intolerance or celiac disease.

Why the IgG food test solves nothing

The Netherlands Nutrition Centre (Voedingscentrum) and the Dutch College of General Practitioners (NHG) are clear on this: a high IgG against a food points to exposure, not intolerance. In other words, your IgG against wheat is often high precisely because you eat bread often, not because you cannot tolerate it. A long avoidance list based on that can needlessly restrict your diet and itself cause deficiencies. The European allergy organisation EAACI also advises against these tests for diagnosing an intolerance.

So what can you do about complaints?

A structured elimination and reintroduction diary, ideally with a dietitian, often gives more insight than an expensive test. You leave out a suspect food for a few weeks, then reintroduce it in a controlled way and note your complaints. If your main complaint is bloating, read what your blood says about stomach complaints. And when in doubt, first rule out celiac disease with a celiac disease blood test, because that is a validated test.

Lactose, fructose and FODMAPs: often the real culprits

Many complaints people attribute to a mysterious intolerance actually come from poorly digestible carbohydrates. Lactose intolerance, a shortage of the enzyme lactase, gives complaints after dairy and is detectable with a breath test. Fructose and the broader group of FODMAPs (fermentable carbohydrates in, for example, onion, legumes and some fruits) cause gas and bloating in sensitive guts. No blood test helps here, but a temporary, guided low-FODMAP diet does, to see which group causes your complaints. The Netherlands Nutrition Centre (Voedingscentrum) stresses that such a diet is meant to test, not to follow strictly for good.

What about histamine intolerance?

Histamine intolerance is a popular topic, but trickier than it looks. There is a blood test for the enzyme DAO (diamine oxidase), which breaks down histamine, but a low DAO on its own does not prove an intolerance. The diagnosis rests mainly on the pattern of your complaints in relation to histamine-rich food, not on a single number. So be careful with expensive test kits that prescribe a strict diet based on one value. A targeted, temporary elimination process with guidance says more here than a snapshot in your blood. What stands out with almost all of these popular tests: they give a lot of results, but little direction. A good dietitian who combines your complaints and your diary usually reaches more usable advice than a list of dozens of supposed culprits.

When not to experiment but to see your GP

Trying things yourself is fine for mild, recognisable complaints, but there are signals where you should seek medical advice straight away: blood in the stool, unintended weight loss, complaints that wake you at night, or complaints that start for the first time after the age of fifty. These are warning symptoms that call for targeted investigation, not a self-test. An expensive intolerance test can actually cause delay by giving a false sense of an answer.

Frequently asked questions

Does an IgG food test work?

The scientific basis is missing. IgG can point to exposure to a food, not to an intolerance. Be careful with long avoidance lists.

How do I know which test is useful?

For a concrete suspicion, such as celiac disease or lactose intolerance, validated tests exist. Discuss with your GP which test fits your complaints.

Can I cut foods myself?

Temporarily and targeted is fine, ideally with guidance. Do not permanently cut a whole food group without reason, as that can lead to deficiencies.

What you can do now

My advice: choose a validated test for a concrete suspicion, and be critical of broad intolerance tests with a long avoidance list. Every blood test result at Vitalcheck includes a professional assessment by a BIG-registered doctor. A blood value is not a diagnosis: always discuss treatment decisions with your GP.

Sources

• NHG guideline on food hypersensitivity. Dutch College of General Practitioners. Accessed 2026.
• Voedingscentrum (Netherlands Nutrition Centre). Food intolerance and testing. Accessed 2026.
• Thuisarts.nl / NHG. I think I cannot tolerate something. Accessed 2026.