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Nutrigenetics and nutrigenomics: what research shows

Reviewed by Dr. Daniel Wallerstorfer, molecular biologist and founder of Novogenia · Updated: 12 October 2026 · Reading time: 11 min

7,500 years of milk: the textbook case of nutrigenetics

Around 7,500 years ago, farmers somewhere between the central Balkans and central Europe kept dairy animals – and drank milk. The catch: most adults back then could barely digest milk sugar. People who carried one particular gene variant could. They had an advantage, and the variant spread (Itan et al., PLoS Computational Biology 2009).

Today we know the exact spot: in Finnish families, the C/T-13910 variant upstream of the LCT gene was completely associated with biochemically verified lactase non-persistence (Enattah et al., Nature Genetics 2002). The “milk variant” is common in people of European ancestry and rare in many other regions of the world.

That is nutrigenetics in one sentence: the same food meets different genes – and therefore works differently. And that is exactly what makes it so valuable for your counseling.

Recipe book and light switch: nutrigenetics or nutrigenomics?

The two terms sound almost identical, but they look in opposite directions:

• Nutrigenetics – the recipe book: Your DNA is like a very long recipe book, and in every person a few recipes read slightly differently. Nutrigenetics asks: how do these differences change the way your client absorbs and breaks down nutrients and responds to diet?
• Nutrigenomics – the light switch: Here, food acts like a switch that turns genes on and off. One example: PPARγ is the control center for the formation of fat cells, and how active its PPARγ2 form is in human fat tissue depends on obesity and nutritional factors (Deeb et al., Nature Genetics 1998).

For your counseling, nutrigenetics is what counts – it is the source of the genetic analyses you discuss with clients. Nutrigenomics provides the foundation: it shows how diet acts all the way into the cell.

A word on language: In plain-language passages of this guide, we often speak of “functioning” or “effective” genes and “impaired” genes. This is a deliberate simplification that we also use in reports. Technically, we are talking about gene variants (polymorphisms) – common differences in the DNA that make a gene somewhat more or less effective, not “broken” genes.

This article answers the question that matters to you as a professional: what does research show – and how do you use it?

Three steps of personalization – each builds on the one below

The International Society of Nutrigenetics/Nutrigenomics (ISNN) describes personalized nutrition as a staircase with three steps (Ferguson et al., Journal of Nutrigenetics and Nutrigenomics 2016):

1. General guidelines for groups by age, sex and social determinants.
2. Individualized nutrition with information on the current state: body measurements, blood and metabolic values, physical activity.
3. Genotype-directed nutrition that additionally considers rare or common gene variants.

Each step makes counseling more personal. Genes show what someone tends toward. The phenotype – measured values and body data – shows where they stand today. Together, they give you the complete picture.

The evidence ladder: how research uncovers gene effects

Picture research as a ladder. Each rung adds a piece of the puzzle – from the lab to everyday life. Well-documented gene effects stand on several rungs at once.

For your counseling, this means: for every claim, ask which rungs it stands on. The more rungs, the firmer the ground.

Where research stands on solid ground

For many gene–nutrient pairs, mechanism, repeated observations and, in part, intervention studies fit together nicely:

• Milk sugar (LCT): the example from the beginning – one of the best-understood links in human genetics.
• Folate (MTHFR): MTHFR is the tool that converts folate into its main circulating form. The 677C>T variant makes this tool less active (Frosst 1995). A meta-analysis in healthy women found a clear gradient in blood folate: highest with two functioning gene copies (CC), lowest with two impaired ones (TT) (Tsang et al., American Journal of Clinical Nutrition 2015).
• Caffeine (CYP1A2): CYP1A2 is your body’s tool against caffeine. A common variant helps determine how far this tool can be ramped up – among smokers, people with the AA genotype broke down caffeine markedly faster (Sachse et al., British Journal of Clinical Pharmacology 1999). In sport, you can see how practical this is: the same caffeine dose made AA carriers faster in a time trial (Guest et al. 2018).
• Omega-3 (FADS1/FADS2): In a genome-wide meta-analysis of 8,866 people, variants in these conversion genes were strongly associated with blood levels of the omega-3 fatty acids ALA, EPA and DPA (Lemaitre et al., PLoS Genetics 2011).

All genes in detail – what they do, what research shows and what it means for counseling – are in The key genes for nutrition counseling.

Where it gets exciting: genes, diet and behavior

Research today goes far beyond single genes. It asks how genes and diet work together – and how people act on their genetic knowledge:

• Gene–diet interaction confirmed: With APOA2, a higher BMI was linked to the CC genotype only when people ate a lot of saturated fat – in three independent populations. The authors describe it as the first gene–diet interaction on BMI to be so strongly and consistently replicated (Corella et al., Archives of Internal Medicine 2009).
• Personal beats general: In the European Food4Me study (1,269 participants completed it), personalized advice – based on the person’s own diet, in part combined with measured values and genes – improved diets more than general recommendations: less red meat, salt and saturated fat, more folate (Celis-Morales et al., International Journal of Epidemiology 2017).
• Genetic knowledge can change behavior: People who carried an ACE variant and were therefore advised to eat less salt reduced their sodium intake more than the control group after 12 months (Nielsen and El-Sohemy, PLoS One 2014). In the NOW trial, only the group with genetic information significantly reduced its fat intake after 12 months (Horne et al., BMJ Nutrition, Prevention & Health 2020).
• Weight as teamwork: For body weight, research has already identified 97 loci (Locke et al., Nature 2015). No single gene decides – from which it follows that good analyses bundle several genes. In an internal Novogenia study with 302 people, participants on a gene-based diet lost around 2.4 times more weight than on a standard diet.

How genes and lifestyle work together is covered in Genes are not destiny: how genes and lifestyle work together.

What professional societies recommend

• ISNN (2016): Differences in the genetic profile affect nutrient requirements, metabolism and the response to diet. Personalized nutrition should build on a solid foundation of knowledge from nutrigenetics and nutrigenomics – and the society sees its role in promoting science and ensuring well-founded claims (Ferguson et al. 2016).
• Evaluation framework (2017): An expert group has developed a framework to assess the scientific validity of a gene–diet claim and whether it is actionable – as a basis for transparent, scientifically sound advice based on nutrigenetic tests (Grimaldi et al., Genes & Nutrition 2017).
• Academy of Nutrition and Dietetics (USA, 2014): Nutritional genomics shows how diet and genotype interact to shape the phenotype. Nutrition professionals need basic competency in genetics for this; family history, lab values and risk factors remain important tools for personalization (Camp and Trujillo, Journal of the Academy of Nutrition and Dietetics 2014).

The common thread: nutrigenetics belongs in competent hands and shows its value together with the dietary history and measured values – which is exactly where your counseling comes in.

Gene, recommendation, follow-through: three levels

Good nutrigenetic counseling keeps three levels apart – and then connects them into a clear plan:

At Novogenia, we put it this way: the genetic traits determined in a genetic analysis are well documented – each gene included is backed by at least three independent studies. The recommendations derived from them are logical conclusions, not scientifically proven. This clarity makes you credible in conversations. More in Explanation of the approach of science.

Checklist: how to recognize well-supported claims

• Size: Was the effect studied in many people?
• Replication: Have independent research groups found it repeatedly?
• Ancestry: Does the population studied match your client? Gene variants differ in frequency around the world – remember the “milk variant”.
• Effect size: How large is the difference in kilograms, percent or minutes?
• Mechanism: Is it known what the gene does in the body?
• Clear separation: Does the report distinguish between the genetic trait and the recommendation?

For your counseling: genes as a building block

• Genes complete the picture: Together with the dietary history, body data and blood values, they make your counseling more personal.
• Tendency, not verdict: Explain results as a predisposition that interacts with diet, exercise and environment. Genes are not destiny – your client can act.
• Name it clearly: The trait is documented; the recommendation based on it is a logical conclusion.
• Hand over the medical part: Analyses related to disease – such as HLA-DQ2/DQ8, HFE, APOE or thrombosis factors – and pharmacogenetics are medical analyses. Where national law requires it, they belong in medical hands.

How to explain results clearly in a conversation is covered in Explaining a genetic report clearly.

Frequently asked questions

Related: The key genes for nutrition counseling · Genes are not destiny: how genes and lifestyle work together · How Novogenia classifies scientific claims

Note: This guide is general information for professionals and does not replace medical or legal advice. The genetic traits determined in a genetic analysis are well documented (each gene included is backed by at least three independent studies); recommendations on nutrition, micronutrients and lifestyle derived from them are logical conclusions, not scientifically proven. Regulations can change; errors and changes excepted.