Nutrigenetics explained: what has been demonstrated and where the limits lie

What to expect in this article

1. Nutrigenetics and nutrigenomics: the difference
2. How professional societies assess the field
3. Why deriving recommendations is so difficult
4. Six cases in which genetics plays a role
5. Lactose intolerance as an illustrative example
6. Celiac disease: predisposition and disease in figures
7. Why a predisposition is not a prediction
8. Three sentences about genetic tests in the fact check
9. What the Genetic Diagnostics Act regulates
10. What a test can do in this context
11. Limitations: what this article does not answer
12. What remains of nutrigenetics
Frequently asked questions
Sources

Nutrigenetics and nutrigenomics: the difference

Two terms stand side by side and refer to opposite perspectives. Nutrigenetics asks how a person’s genetic information influences what a food does in the body. Nutrigenomics asks, conversely, how nutrients affect the genetic material and its expression.

A definition of the second field appears in the Bundesgesundheitsblatt: Nutrigenomics is a field of research that examines the interaction between nutrition and the genome.

The size of the genome

The MSD Manual gives one figure for the scope of what is being discussed here: humans have around 20,000 to 25,000 genes. We did not find a reliable figure for the number of base pairs in the sources we reviewed and therefore do not provide one.

This figure alone says little about the informative value of a test. What matters is how many of these genes are involved in a particular trait and how strongly each one acts. The assessment in the next chapter depends on precisely that.

How professional societies assess the field

In 2023, the North Rhine-Westphalia Consumer Advice Centre compiled the assessments of several professional societies. The statement by a working group of the German Nutrition Society is reproduced there verbatim.

We quote this statement even though mybody®x itself offers DNA tests for nutrition. What this means for our own offering is set out in Chapter 10—and it does have implications.

What other professional societies say

The same special publication presents the position of the German Society for Human Genetics, according to which the potential dangers of misinterpretation or overinterpretation are assessed as substantially greater than the advertised benefit. Regarding microbiome analysis from a stool sample, it quotes the German Society for Gastroenterology, which advises against it because a single undefined sample is not scientifically meaningful enough.

In 2013, the German Ethics Council commented on lifestyle genetic tests and described them as having only a weak scientific foundation, based, for example, on individual small-scale studies. The same statement says that it remains unclear how meaningful the data obtained are and what relevance they have for lifestyle.

Why deriving recommendations is so difficult

The professional societies' criticism is not directed against the existence of genetic differences. It is directed against inferring a course of action from these differences. One figure illustrates the problem.

The special publication by the North Rhine-Westphalia Consumer Advice Centre lists 941 known gene loci for obesity and 240 identified gene loci for type 2 diabetes. Hundreds of sites in the genome therefore contribute to the same characteristic, each with only a small effect.

What follows from this

A test that reads only a few of these sites captures a fraction of the picture. Deriving a dietary recommendation from this fraction assumes that the part captured is decisive.

This is precisely the evidence that the professional societies find lacking. The special publication states the methodological core: there is insufficient evidence from randomized controlled trials on the effectiveness of incorporating genetic tests into nutritional counseling.

The crucial term is effectiveness. The question is not whether a test reads the variants correctly, but whether people ultimately eat more healthily or become healthier with this additional information.

Six cases where genetics delivers

Between the fundamental caveat and actual practice lies a range of cases in which a single gene genuinely makes the difference. The table brings them together.

The last two lines are the most honest ones in the table. Percentages circulate for both cases, but we did not find them in the institutional sources we reviewed.

Lactose intolerance as a teaching example

No condition shows the connection between genetic information and nutrition as clearly as lactose intolerance. IQWiG describes it as usually hereditary and refers to an inherited or primary form.

Lactose intolerance in numbers

Source: Institute for Quality and Efficiency in Health Care (IQWiG), Lactose Intolerance; Consumer Advice Centre NRW, Personalized Nutrition (2023)

Why the difference between the regions is so large

The range from 5 to over 90 percent is among the largest differences that can be reported for any nutritional trait. It shows how strongly a single gene can act when it actually makes the difference.

At the same time, it reveals a pitfall. Concluding from this case that dietary recommendations can generally be justified genetically means treating an exception as the rule. For most traits, the situation is more like obesity, which involves 941 genetic loci.

What makes this case so unusual

In lactose intolerance, three conditions come together, and all three are rare. A single gene is decisive, the condition is clearly noticeable, and the resulting course of action is clear.

Most dietary questions lack at least one of these conditions. When hundreds of genetic loci are involved, when the condition develops gradually, or when the result does not lead to a clear course of action, a test result loses its practical value.

It is also noteworthy that lactose intolerance is usually diagnosed in clinical practice without genetic testing. A breath test or a challenge test shows the condition directly, whereas genetic testing shows the predisposition.

Celiac disease: The predisposition and the disease in numbers

Celiac disease is the clearest example of the difference between a predisposition and a disease. The IQWiG cites three figures that belong together.

In Germany, slightly more than 30 out of 100 people carry the genetic predisposition, specifically the HLA genotypes DQ2 or DQ8. About 1 to 2 percent of people in Europe have confirmed celiac disease. And only about 2 to 3 out of 100 people with this predisposition actually develop celiac disease.

What genetic testing can do here

These three figures point to a clear division of roles. People who do not carry the predisposition are highly unlikely to develop celiac disease, so the test can largely rule it out. Those who do carry it, however, learn little, because 97 to 98 out of 100 carriers remain healthy.

A test with this structure is useful for ruling something out, not for predicting it. This is relevant for relatives: According to the same text, about 10 to 15 out of 100 first-degree relatives of people with celiac disease are also affected.

Why the process still leads through the doctor’s office

Even when used appropriately, genetic testing does not come first in celiac disease. Diagnosis is based on antibodies in the blood and, in many cases, a tissue sample from the small intestine.

The sequence is important. Anyone already eating gluten-free will distort the antibody test because the reaction does not occur without a trigger. Changing one’s diet before diagnostic testing can therefore make the evaluation more difficult.

In this process, the genetic test plays a supporting role as a tool for ruling things out. It does not replace diagnostic testing, nor does it come before it.

Why a genetic predisposition is not a prediction

What became apparent in celiac disease applies more generally. The technical term for this is incomplete penetrance: A variant is present but does not lead to the trait being expressed in all carriers.

The figures come from the MSD Manual and refer to homozygous carriers of the C282Y variant in the HFE gene, the cause of more than 80 percent of hemochromatosis cases. Among people of Northern European ancestry, the variant is by no means rare, occurring in 1 in 200.

What this means for a test result

A finding that identifies a variant describes a possibility, not a condition. Other factors lie between genetic predisposition and its expression, and a genetic test does not capture them.

This is precisely where the concern of the German Society of Human Genetics comes in: it considers the risks of misinterpretation or overinterpretation greater than the advertised benefit. A result without context is easily read as a diagnosis, but it is not one.

Three statements about genetic tests in a fact check

Three claims appear in advertising for DNA nutrition tests. We compare them with the sources for this article.

The three assessments come from three different professional societies and point in the same direction. That is the finding an article on this topic must convey, even if it is produced by a provider.

What the Genetic Diagnostics Act regulates

In Germany, genetic examinations are governed by a specific law. Two paragraphs are particularly important for this topic.

Paragraph 7 governs the medical reservation: Genetic examinations for medical purposes may be carried out only by physicians; predictive examinations only by specialists in human genetics or equivalently qualified physicians. Paragraph 9 governs counseling: Before consent is given, patients must be informed about the nature, significance, and scope of the examination, with adequate time to consider it.

The unresolved distinction

Exactly where the boundary lies between a medical purpose and a purely lifestyle purpose has not been conclusively clarified by law. A 2024 legal assessment adopts a broad interpretation under which tests related to health, such as those for food intolerances, also fall under the requirement for physician involvement.

We name this uncertainty instead of glossing over it. Since February 1, 2012, genetic counseling in connection with genetic testing may also be provided only by specially qualified physicians.

Why the law is so strict

The strictness has a reason that goes beyond data protection. A genetic finding affects not only the person tested but, in part, their relatives as well, because they may carry the same predispositions.

There is also the irreversibility. A blood value can be retested in six months and may have changed. A genetic variant remains, and the information about it cannot be taken back.

That is precisely the purpose of the duty to provide information under Section 9, with its appropriate reflection period. It is intended to ensure that before taking the test, someone knows what they will no longer be able to unknow after taking it.

For consumer tests without medical supervision, this leaves a vulnerability. Consumer advice centers sum up the practical consequence in one sentence: Without proper interpretation, the results could unsettle and overwhelm you.

What a test can do within this framework

After nine chapters with clear reservations, the question remains: What does a DNA test for nutrition actually provide? The honest answer is narrower than the advertising for this product category usually suggests.

It reads genetic variants and describes predispositions. It provides no diagnosis, no prediction of illness, and no dietary recommendation with proven effectiveness. The cited DGE working group rejects precisely this last point, and the same applies to our tests.

mybody®x works with a certified specialist laboratory in Germany, conducts its analyses in compliance with the GDPR, and has been active since 2016, operating in the direct-to-consumer market since 2022.

DNA test from saliva

NutriCare | INFINITY DNA Test

More than 140 genetic variants from a saliva sample, evaluated in 54 analysis reports. What the test does not do: It does not diagnose, predict illness, or replace medical advice. The cited DGE working group states that evidence-based dietary recommendations cannot currently be derived from genetic makeup. This finding applies here as well.

Price €269.00 As of 11 August 2026; subject to change

Sample type Saliva sample

Processing time Approx. 20–25 working days after the sample arrives at the laboratory

Laboratory Certified specialist laboratory
Product page information, accessed 11 August 2026

About the NutriCare DNA test

Limitations: what this article does not answer

We did not find a Germany-specific percentage for lactose intolerance. The stated 5 to 15 percent refers to people from Europe, and we report it as it appears in the sources.

None of the preferred sources provides a figure for the number of base pairs in the human genome. The commonly cited figure of three billion is therefore not included in this text.

For alcohol breakdown via ALDH2 and caffeine breakdown via CYP1A2, we found no reliable percentages in the preferred institutional sources. Both associations have been described, but we do not quantify them nonetheless.

Finally, a limitation concerning this article itself. This article does not assess whether a DNA nutrition test is useful. It reports what professional organizations say about it and leaves the decision to the reader. If there is a specific suspicion of an intolerance or disease, the appropriate route is medical diagnosis.

What remains of nutrigenetics

If you take one distinction away from this article, let it be the distinction between ruling something out and making predictions. It determines what a genetic finding is worth to you.

Celiac disease demonstrates both points with the same figures. Anyone who does not carry the genetic predisposition can practically rule out the disease. Those who do carry it belong to a group in which 97 to 98 out of 100 people remain healthy. The same test is informative in one case and almost meaningless in the other.

It began with the question of how much nutrigenetics determines our lives. The most reliable answer is: very clearly in a few areas, and so little in most areas that no recommendation can be derived from it.

Frequently asked questions

Sources

1. Consumer Advice Center NRW: Personalized Nutrition – Can Genetic Testing and a Stool Sample Lead to Success? Reprint from Knack•Punkt, Issue 1/23, as of 2023 – verbraucherzentrale.nrw
2. Institute for Quality and Efficiency in Health Care (IQWiG): Celiac Disease (Gluten Intolerance) and Lactose Intolerance – gesundheitsinformation.de
3. MSD Manual: Introduction to Genetics, Phenylketonuria, and Hereditary Hemochromatosis – msdmanuals.com
4. Federal Ministry of Justice: Act on Genetic Examinations in Humans (Genetic Diagnostics Act – GenDG), 2009, as subsequently amended – gesetze-im-internet.de

The verbatim quotation from the DGE working group, the note on the lack of evidence from randomized controlled studies, the figures of 941 and 240 gene loci, the positions cited from the German Society for Human Genetics and the German Society for Gastroenterology, and the statement concerning the lack of classification are taken from source [1]. The figures on lactose intolerance, the HLA gene types DQ2 and DQ8, the prevalence of celiac disease, and the proportion of affected first-degree relatives are taken from [2]. The figure of 20,000 to 25,000 genes, the information on phenylketonuria, and all figures concerning hemochromatosis are taken from [3]. The physician reservation and the duty to provide information are taken from [4]. Additional citations include: the definition of nutrigenomics from the Bundesgesundheitsblatt (2006); the assessment of lifestyle genetic tests from an opinion of the German Ethics Council (2013); the information on genetic counseling since February 1, 2012, from an overview by the Berlin Medical Association; and the legal assessment of the broad interpretation of the physician reservation from a publication by the Data Protection Expertise Network (2024). Information on price, scope, sample type, and laboratory comes from the mybody®x product page, accessed on August 11, 2026. All sources were accessed and reviewed on August 11, 2026.

mybody®x Editorial & Expert Team

Laboratory diagnostics Nutritional science Blood analysis interpretation Nutrigenetics

This article was created by the mybody®x editorial and expert team. The team combines laboratory diagnostics, nutritional science, and the interpretation of blood analyses. Those who contribute to it are listed on the authors page.

Published on April 2, 2025 · Last updated on August 11, 2026

The content is intended for general information and does not replace medical advice, diagnosis, or treatment. Reference ranges depend on the laboratory, method, and age—your test report always provides the authoritative information.