Blood test for food intolerances: How to identify a reputable service
The essentials at a glance
You can recognize a reputable blood test for food intolerances by the fact that the provider openly states what an IgG finding does not prove: IgG antibodies can also be detected in people without symptoms. Reputable providers also clearly distinguish between IgG screening, the hydrogen breath test for lactose and fructose intolerance, and medical testing for coeliac disease—and point out warning signs that always require medical examination.
This page explains what an IgG blood test actually measures, dispels the two most common misconceptions about blood tests for intolerances, and compares IgG blood tests, hydrogen breath tests, IgE blood tests, and food diaries based on the same four criteria. This gives you a basis for assessing offers yourself—regardless of which provider is behind them.
Chapter 1 answers the initial question directly, while Chapter 2 dispels myths. Chapter 3 presents the free first step, and Chapter 4 compares the four methods at a glance. Chapter 5 presents a specific testing option in practice, while Chapter 6 outlines the limitations.
What to expect on this page
1. How can I find a reputable blood test for intolerances?
2. What myths surround IgG blood tests?
3. What is the best first step if an intolerance is suspected?
4. Which method is suitable for which question?
5. How does mybody®'s NutriCheck work in practice?
6. What a blood test cannot do
Conclusion
Frequently asked questions
Sources
How can I find a reputable blood test for intolerances?
A reputable blood test for intolerances openly states that an IgG finding does not prove an intolerance: The antibodies can also be detected in people without symptoms and primarily reflect eating habits. Reputable providers also distinguish between IgG screening and the established standard procedures for lactose intolerance, fructose intolerance, and coeliac disease.
The most important point to check first: IgG antibodies against foods can also be detected in people without any symptoms. A result showing many reactions often does not explain the symptoms; it mainly shows what someone eats frequently.
This leads to a second criterion: A provider that markets IgG levels as a diagnosis of an intolerance is concealing precisely this connection. Reputable providers, by contrast, use cautious wording—as an indication for further observation, not as proof.
How to recognize a reputable provider
- ✓ Uses cautious wording—an IgG finding is considered an indication, not a diagnosis.
- ✓ Identifies the hydrogen breath test as the standard for lactose and fructose intolerance, not IgG screening.
- ✓ Recommends medical antibody testing for tissue transglutaminase if celiac disease is suspected.
- ✓ Identifies warning signs such as blood in the stool, fever, or significant weight loss as reasons for immediate medical evaluation.
- ✓ Uses an ISO-certified laboratory with a transparent, realistic turnaround time.
The hydrogen breath test for lactose intolerance illustrates how precisely an established procedure can be described. The Institute for Quality and Efficiency in Health Care (IQWiG) describes the process as follows:
“
“After drinking a lactose solution, the hydrogen content in the breath is measured several times. It is usually elevated in people with lactose intolerance.”
Institute for Quality and Efficiency in Health Care (IQWiG)
gesundheitsinformation.de, “Lactose intolerance (milk sugar intolerance),” as of November 6, 2024
An IgG blood test does not have a comparably clear, well-described mechanism of action for an intolerance to a specific food. This alone indicates how differently the two procedures should be classified.
Key message: A reputable provider never markets an IgG blood test as proof of an intolerance, but rather as a starting point for further observation.
What myths surround IgG blood tests?
Two persistent misconceptions surround IgG blood tests: that a positive result proves an intolerance and that lactose intolerance can be diagnosed through a blood test. Neither assumption stands up to closer examination.
Why do IgG antibodies develop at all?
IgG antibodies are part of the normal immune response to dietary proteins that are regularly absorbed through the intestine. The body produces them against many foreign proteins, not just disease-causing pathogens—this is part of ordinary immune surveillance and, in itself, is not a sign of disease.
The more frequently and in larger quantities a food is eaten, the more likely it is that IgG antibodies to it can be detected. A result showing an unusually large number of reactions therefore initially says above all something about a person's previous diet: someone who eats wheat products, milk, or eggs every day is more likely to show IgG reactions to precisely these foods than someone who eats them only rarely. This explains why broad IgG panels often produce a long list of reactions that does not necessarily correspond to the actual symptoms.
A third misconception concerns celiac disease: it is not diagnosed using IgG antibodies against foods. The path to diagnosis involves testing for antibodies against tissue transglutaminase in the blood, followed by medical evaluation, usually including a gastroscopy.
Why, then, does the first myth persist so stubbornly? Because a result with many positive reactions initially looks like a clear finding. In reality, it mainly describes eating habits and does not necessarily indicate an intolerance.
What is the best first step if you suspect an intolerance?
The most reliable first step when a food intolerance is suspected is to keep a food and symptom diary for two to three weeks. It costs nothing, makes any subsequent evaluation more targeted, and shows whether there is a recurring pattern at all.
Many symptoms that people attribute to a single food occur as part of irritable bowel syndrome. According to IQWiG estimates (as of 2023), around 10 to 20 out of 100 people have irritable bowel syndrome.
However, how people react to particular foods varies greatly from person to person, as IQWiG notes in its guide to irritable bowel syndrome. That is precisely why a diary makes this individual reaction visible in the first place, before any test is ordered.
Intolerance, allergy, or irritable bowel syndrome: what is the difference?
The three terms are often used synonymously in everyday life, but they describe different mechanisms. A food intolerance usually involves digesting a particular substance, such as the milk sugar in lactose intolerance, without the involvement of the immune system. An allergy, by contrast, is an immune reaction in which IgE antibodies play the central role and which can also be acute and severe. Irritable bowel syndrome, on the other hand, is not a reaction to a single food but a functional disorder of the digestive tract in which certain foods may merely trigger or aggravate symptoms without being their actual cause.
This distinction explains why an IgG blood test provides little useful information for irritable bowel syndrome: it tests an immune reaction that has nothing to do with the underlying functional disorder. Anyone keeping the symptom frequency mentioned in the previous section in mind can also see why careful observation over several weeks reveals more about the actual cause than a single laboratory result.
Before you begin observing or testing, certain warning signs should be reported to a doctor's office immediately. IQWiG lists significant weight loss, blood in the stool, fever, or pallor. Blood in the stool should always be medically evaluated to determine the cause.
How to keep a food and symptom diary correctly
For each meal, record four details: the time, exactly what you ate, which symptom occurred afterward, and how much time passed between the meal and the symptom. The time interval is particularly important because some reactions occur within minutes, while others do not appear until several hours later.
Over two to three weeks, this produces a pattern that is difficult to reconstruct from memory alone. Only when a food repeatedly appears alongside the same symptom and the same time interval is the next step worthwhile: a targeted, time-limited elimination trial of that one suspected food—not several food groups at once. This keeps the elimination trial manageable, and the connection can then be confirmed or ruled out by cautiously reintroducing the food.
Anyone who consistently eliminates individual food groups after keeping a diary, for example as part of a low-FODMAP diet, should not continue doing so on their own for weeks. According to IQWiG, this carries a risk of malnutrition because it becomes difficult to obtain enough vitamins and minerals. Such an elimination diet should therefore be professionally supervised, for example by a nutrition professional.
The risk does not arise from a short, targeted test phase lasting a few days, but from permanently omitting entire food groups without professional guidance. Anyone who avoids dairy products, grains, or several FODMAP-rich groups at the same time for weeks or months without consultation risks exactly the unbalanced diet IQWiG warns about. A nutrition professional can provide guidance on which foods to eliminate as a trial, how long the elimination phase should last, and how reintroduction should be carried out—so that ultimately no more foods are avoided than necessary.
In brief
The first step when suspecting a food intolerance is a two- to three-week food and symptom diary, not a blood test. Warning signs such as blood in the stool, fever, pallor, or significant weight loss always require immediate medical attention. Elimination diets carry a risk of malnutrition and should be professionally supervised.
Which method is suitable for which question?
IgG blood tests, hydrogen breath tests, IgE blood tests, and food diaries address different questions and therefore cannot be substituted for one another. The following overview compares all four using the same four criteria.
| Criterion | IgG blood test | Hydrogen breath test | IgE blood test | Food diary |
|---|---|---|---|---|
| What is examined | IgG antibodies against up to 300 foods in the blood | Hydrogen levels in exhaled air after a sugar solution | IgE antibodies, typical of immediate-type allergies | Timing between a meal and symptoms |
| What it is the standard for | Not a recognized diagnostic procedure for an intolerance | Lactose and fructose intolerance (medical standard) | Classic immediate-type allergy | Narrow down an initial suspicion before targeted testing |
| Limitations | Also produces positive results in people without symptoms | Does not detect IgG-mediated reactions or allergies | Does not detect lactose or fructose intolerance | Does not provide a laboratory report and depends on accurate documentation |
| Effort involved | One-time blood sample at home | Several breath samples over 2 to 3 hours, usually at a medical practice | One-time blood sample | Two to three weeks of daily documentation, free of charge |
For lactose and fructose intolerance, the hydrogen breath test is considered the medical standard. mybody® (MYBODY Lab GmbH) does not offer a standalone test product for this purpose—instead, anyone seeking to clarify this suspicion should consult a medical practice or a specialized laboratory.
This page deliberately differs from a general test selection guide: Anyone who is still unsure which type of test is appropriate for their symptoms can find broader guidance in the guide Find the right health test.
How does the mybody® NutriCheck work in practice?
mybody® (MYBODY Lab GmbH) operates an ISO-certified laboratory in Germany and complies with the GDPR. To determine which IgG reactions are currently detectable in the blood, the company offers NutriCheck as a capillary blood test for home use.
A result showing many reactions often does not explain the symptoms.
NutriCheck | Intolerance Test
NutriCheck measures specific IgG antibodies against up to 300 foods in 13 categories from a capillary blood sample. It does not detect lactose intolerance, fructose intolerance, coeliac disease, or a classic immediate-type allergy. An IgG result is an indication for further observation, not proof of an intolerance.
Price: €169.00 (instead of €199.00) · Sample type: Capillary blood · Processing time: approx. 3–5 business days · Laboratory: ISO-certified laboratory analysis
About NutriCheckAll price and service information is current as of August 3, 2026. Prices and processing times may change.
What a blood test cannot do
An IgG blood test can only measure what it was designed to detect: antibodies against food proteins. Other similarly common reactions to food require different methods.
Why lactose intolerance is not a case for antibody testing
Lactose intolerance is widespread, but it is not a case for a blood test. According to IQWiG (as of 2024): “Around 5 to 15% of people in Europe cannot tolerate lactose. Lactose intolerance is least common in Northern Europe. In Africa or East Asia, by contrast, 65 to over 90% of adults are affected.”
The reason lies in the enzyme, not the immune system. The IQWiG describes how it develops: “When an adult consumes more lactose than lactase can break down, lactose remains in the small intestine. It passes into the large intestine, where it is broken down by intestinal bacteria (known as fermentation). This produces increased amounts of gases such as carbon dioxide (CO2) and hydrogen, as well as other breakdown products such as fluid and fatty acids in the intestine, which cause the typical symptoms.” An IgG blood test fundamentally cannot detect this enzyme deficiency.
Why coeliac disease requires different antibodies
Coeliac disease cannot be diagnosed through IgG antibodies against foods either. It is diagnosed through antibodies against tissue transglutaminase in the blood, followed by medical evaluation—not through screening for food reactions.
An unremarkable IgG result is not a free pass either: it rules out neither lactose or fructose intolerance nor coeliac disease or a true allergy. If, after keeping a food diary, you still have a specific suspicion, clarify it with the appropriate standard test or at a doctor’s office.
If the cause is more likely rooted in digestion itself than in individual foods, it is worth consulting the recommendations for the gut flora test.
Conclusion
A reputable blood test for food intolerances never presents an IgG result as proof, but as a starting point for further observation. The most affordable first step remains a food and symptom diary; for lactose and fructose intolerance, the hydrogen breath test; and for coeliac disease, medical antibody testing.
Knowing these differences helps you order more selectively and interpret a result more realistically—and understand when a test is actually the right next step.
Frequently asked questions
How can I find a blood test that detects food intolerances?
Make sure the provider clearly explains what an IgG result does not prove: IgG antibodies against foods can also be detected in people without symptoms and primarily reflect eating habits. A reputable service also clearly distinguishes between IgG screening, the hydrogen breath test for lactose and fructose intolerance, and medical testing for coeliac disease; identifies warning signs such as blood in the stool as a reason to seek immediate medical evaluation; and uses an ISO-certified laboratory. In any case, the most reliable first step before any blood test is a two- to three-week food and symptom diary.
Does a positive IgG result prove a food intolerance?
No. IgG antibodies against foods can also be detected in people without symptoms and reflect what someone regularly eats more than an intolerance. A result showing many positive reactions therefore often does not explain the symptoms and is, at best, considered an indication for further observation, not a diagnosis.
Can an IgG blood test detect lactose intolerance?
No. Lactose intolerance is caused by a deficiency of the enzyme lactase, not an antibody reaction—an IgG blood test therefore cannot detect it in principle. The medical standard is the hydrogen breath test, in which the hydrogen content of the exhaled air is measured several times after drinking a lactose solution (IQWiG, 2024). mybody® does not offer a separate test product for this.
What is the best first step if you suspect an intolerance?
Keep a food and symptom diary for two to three weeks, recording the time, meal, and symptom. It costs nothing and makes any subsequent evaluation more targeted because you will already know what to look for. Afterward, you should not follow elimination diets without professional guidance, as they carry a risk of nutritional deficiencies. If you have warning signs such as blood in the stool, fever, pallor, or significant weight loss, seek medical evaluation immediately rather than relying on a diary.
Intolerance Tests at a Glance
If you have decided to take a blood test for intolerances, you can find the right analysis in the overview.
View intolerance testsYou may also be interested in
→ Find the Right Health Test: A Guide Based on Symptoms
How to distinguish between blood, gut flora, and DNA analyses before ordering a test.
→ Gut Flora Tests with Actionable Recommendations
In case the cause lies more in digestion itself than in individual foods.
→ Biomarker Encyclopedia: 67 Blood Values Explained Simply
Reference guide to every individual blood value before you decide to have an analysis.
Sources
- Institute for Quality and Efficiency in Health Care (IQWiG): Lactose intolerance (milk sugar intolerance), as of November 6, 2024 — gesundheitsinformation.de
- IQWiG: Irritable bowel syndrome, as of February 22, 2023 — gesundheitsinformation.de
- IQWiG: What helps with irritable bowel syndrome—and what doesn’t? As of February 22, 2023 — gesundheitsinformation.de
The information on the prevalence and development of lactose intolerance, as well as the quote about the hydrogen breath test, comes from [1]. The information on irritable bowel syndrome and the warning signs mentioned comes from [2]. The statement about the individuality of food reactions and the risk of malnutrition with elimination diets comes from [3]. All product information comes from the mybody® product page, accessed on August 3, 2026.
mybody® Editorial & Expert Team
Intolerances Laboratory diagnostics Nutritional science
This page was created and medically reviewed by the mybody® Editorial and Expert Team. The team brings together expertise in laboratory diagnostics, blood analysis interpretation, and nutritional science.
Last updated on August 3, 2026
Medical notice: This page is for general information and does not replace medical advice, diagnosis, or treatment. None of the tests presented here provides a diagnosis. If you experience warning signs such as blood in your stool, fever, pallor, or significant weight loss, please consult a medical practice first.
