Genetics and Nutrition: What a DNA-Based Diet Really Means

Keto or low-fat? More protein or fewer carbohydrates? Intermittent fasting or intuitive eating?

How many more diets do you need to try before you finally find the one that really works? Perhaps it is worth starting not by looking for the answer to “what should I eat?”, but by trying to understand what your body in particular needs?

Nutrition that lets you feel energetic, support your physical and emotional health and move towards your own goals begins not with a list of foods but with an understanding of how the body interacts with food — how it metabolises fats, carbohydrates and amino acids, how it responds to lactose, caffeine and particular fatty acids. These processes are linked to genetic features. A DNA test helps you understand which of these features are worth taking into account, so as to set nutrition priorities more precisely.

What You Can Actually Learn from Your Genetic Profile

What does this information mean in practice? A genetic profile can reveal features linked to the metabolism of fats and carbohydrates, the regulation of appetite and the tolerance of individual food components. It does not sort foods into “allowed” and “forbidden” but helps you understand which parameters of your diet — the composition of carbohydrates and fats, the eating pattern or the tolerance of particular foods — are worth monitoring or adjusting.

Carbohydrates

Why does the metabolic response to carbohydrate foods differ between people? In part this has to do with genetic features that affect glucose regulation, the secretion and action of insulin, or the risk of unfavourable metabolic changes (Ramos-Lopez, World J. Diabetes, 2024).

This does not mean that carbohydrates are “off-limits” for you. A DNA test does not determine your actual glucose level or insulin resistance. But its result can suggest what exactly — carbohydrates in the diet, glucose control or other factors of metabolic risk — is worth assessing more closely.

Fats

Genetic variants can be associated with differences in the metabolism of triglycerides, cholesterol and lipoproteins, as well as with an unequal response of lipid indicators to the composition of the diet (Pérez-Beltrán et al., Front. Nutr., 2022). This may be one of the factors behind why the same amount and composition of fats affect the lipid indicators of different people differently.

This suggests that it is worth paying attention not only to the amount of fats but also to their sources and the ratio of saturated to unsaturated fatty acids — and, where needed, checking an up-to-date lipid panel.

Can this information be used to claim that a particular model of eating — low-carbohydrate, low-fat or perhaps ketogenic — genetically “suits” a person? That is a separate question, one that requires setting the genetic test results against the body’s current state, blood test results and the person’s health goals.

Appetite and Eating Behaviour

Why is it harder for some people to control portion size or to resist snacking? Studies describe genetic associations with food preferences, taste perception and the regulation of appetite, though these traits depend not only on genetics but also on environment, sleep, stress and habits (Hejazi et al., BMC Nutr., 2024).

This does not explain behaviour by “genes”, but it helps you choose a more realistic structure for your diet — the frequency of meals, the composition of dishes, the role of snacks — that is, a strategy you can realistically keep to over a long time. Even a biologically sound scheme has no value if it cannot be followed consistently.

Genetic associations with appetite also do not automatically explain why the effort put in does not bring the desired changes in body weight.

Food Intolerances

For some food components the genetic links are better studied than for complex metabolic reactions. One such example is lactase persistence — that is, the retention of the enzyme lactase’s activity into adulthood.

Variants in the regulatory region of the MCM6 (minichromosome maintenance complex component 6) gene, which affects the expression of the neighbouring LCT (lactase) gene, are linked to the retention of lactase activity after childhood (Anguita-Ruiz et al., Nutrients, 2020). These features may explain why lactose tolerance differs between people.

A similar distinction applies to coeliac disease: genetic prerequisites may be necessary for the disease to develop, but their presence does not confirm a diagnosis (Gnodi et al., World J. Gastroenterol., 2022).

So the result of a genetic test on its own is not grounds to exclude a food outright and for good: first it is worth setting the information obtained against symptoms and the results of other examinations.

For more on the genetic features linked to the body’s reactions to lactase and gluten, see the article Food allergy and intolerance: how to tell them apart and what to do.

How to Turn Genetic Test Results into a Decision

Genetic information takes on practical meaning only when it is clear which question it is meant to help answer. That might be improving the lipid profile, stable energy through the day, reducing discomfort after eating, assessing the tolerance of a particular food component, or choosing a model of eating that can realistically be kept to for life.

The result of assessing a single genetic indicator cannot be turned into a direct recommendation. Most hereditary features linked to metabolism, appetite and eating behaviour are complex in nature and depend on the combined contribution of many genetic variants. Even a polygenic estimate remains probabilistic: it shows a predisposition relative to a reference population group, it does not predict an individual scenario.

This is why it is important to set a genetic profile against the body’s actual state: to assess blood glucose, the lipid panel, indicators of liver function and nutrient levels, and also to take symptoms, complaints and eating behaviour into account. Laboratory tests and genetic testing do not replace each other: the former show the current state, the latter adds a stable hereditary context. Such a comparison helps to form a specific hypothesis about nutrition — for example, whether it is worth reconsidering the quality and distribution of carbohydrates, the sources of fats, the structure of meals, or checking the reaction to a particular component of the diet. Decisions are judged not by the genetic result alone but also by changes in wellbeing, symptoms and laboratory indicators.

This approach — form a hypothesis, make changes, track the response and, on the basis of the results, adjust your next steps — matches the logic of personalised nutrition, in which genetic data are set against laboratory indicators, symptoms and eating behaviour. None of these layers of information can correctly be treated as a self-sufficient basis for choosing a diet (Mathers, EFSA J., 2019).

An Apixmed Prism report is built on exactly this logic: genetic results are presented not as a list of individual variants but as structured indicators with an explanation of their possible meaning and impact. The Digestion, immunity and metabolism DNA test groups together the indicators that help examine the genetic features linked to nutrient metabolism, digestion, the tolerance of individual food components and other metabolic processes.

The Scope and Limits of a Genetic Profile for Choosing a Diet

A genetic profile on its own cannot determine what exactly you need to eat. The body’s response to a diet depends on many factors — current health, sleep, stress, physical activity, eating habits and the composition of the microbiome. Unlike genetic variants, these can change over the course of life and affect the outcome of a chosen model of eating in different ways.

For the other factors that change the body’s response to a diet, see the article Why the same diet gives different results in different people.

A genetic test does not determine your exact daily calorie intake, an individual ratio of proteins, fats and carbohydrates, a ready-made menu, your current glucose or cholesterol level, the presence of a disease or a guaranteed reaction to a particular food. Nor can it establish a single model of eating that will remain optimal under any circumstances.

The reason is not a limitation of the genetic test. The metabolic response to food is a complex, systemic trait. Most characteristics linked to metabolism, appetite and eating behaviour are polygenic in nature: numerous genetic variants are associated with them, each making its own contribution. The significance of these associations may also depend on the population and the conditions of the study (Marcum, Curr. Nutr. Rep., 2020; Lee et al., Am. J. Clin. Nutr., 2022; Antwi, Curr. Nutr. Rep., 2023).

Moreover, a person does not consume individual nutrients: every food, dish and diet is a combination of macro- and micronutrients. Their effect is overlaid by the eating pattern, sleep quality, level of physical activity, the influence of stress and environment, and the ability to keep to the chosen model over the long term. So interpreting a single variant as a direct recommendation is, in most cases, incorrect. A combined assessment of genetic data together with data on current health is more informative.

The Best Nutrition Strategy Begins Not with a Diet but with Understanding Your Own Body

Genetic testing can complement an examination when a person has persistent complaints or unusual reactions to food but standard tests show no deviations from the norm. For example, digestive discomfort occurs after certain foods, a change in the ratio of fats to carbohydrates noticeably affects wellbeing, appetite is hard to control, or several different models of eating have not brought the expected result.

Another reason to consider a genetic test is a family history of disorders of carbohydrate or lipid metabolism, coeliac disease or other conditions linked to metabolism and the reaction to food.

Can a genetic test be used to select a diet?

Not in the literal sense. A test can reveal hereditary features that help identify directions for personalisation, but it does not produce a single correct diet. A nutrition strategy must also take into account laboratory indicators, symptoms, lifestyle, eating behaviour and the person’s goals.

Will a test show how many carbohydrates or fats I need to consume?

A genetic test does not determine the exact amount of macronutrients or the corresponding requirement for them. It can point to genetic features of the processes linked to the metabolism of fats and carbohydrates. The specific ratio of nutrients should be determined taking into account energy needs, physical activity, laboratory indicators and the body’s reactions.

Does a higher genetic predisposition mean a food should be excluded?

A genetic result can indicate that the reaction to a particular food component is worth checking, but it is not grounds to exclude a food automatically. A decision to exclude or limit the consumption of one food or another should rest on symptoms, the body’s actual reaction and the results of the relevant examinations.

Is a DNA-based diet better than general recommendations?

A DNA-based diet does not negate the value of the basic principles of healthy eating, but it can help make them more precise and effective for a particular person. A genetic profile helps take into account the genetic features of nutrient metabolism, appetite and the reaction to individual food components, and adds an individual biological context for a well-grounded choice of eating style (Celis-Morales et al., Int. J. Epidemiol., 2017).

The results of a genetic test are not a diagnosis and not a substitute for a doctor’s consultation. An Apixmed Prism report provides genetic context that complements the findings of examinations and helps you make decisions together with your doctor. If there are acute symptoms or an established diagnosis of a disease, a clinical assessment is needed first.

Sources

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4. Marcum, J. A. (2020). Nutrigenetics/Nutrigenomics, Personalized Nutrition, and Precision Healthcare. Current Nutrition Reports, 9(4), 338–345. https://doi.org/10.1007/s13668-020-00327-z

5. Ramos-Lopez, O. (2024). Genotype-based precision nutrition strategies for the prediction and clinical management of type 2 diabetes mellitus. World Journal of Diabetes, 15(2), 142–153. https://doi.org/10.4239/wjd.v15.i2.142

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