Can a genetic methylation study tell us which vitamins we need?

First, what is methylation?

Methylation is a set of fundamental biochemical reactions through which our body transfers small chemical groups called methyl groups.

These processes are involved in numerous functions: regulation of gene expression, homocysteine metabolism, synthesis and metabolism of certain neurotransmitters, phospholipid metabolism, and many other cellular reactions.

Particularly important nutrients participate in these pathways, such as folate (vitamin B9), vitamin B12, vitamin B6, riboflavin (B2), choline, and methionine. We are therefore talking about a truly important part of our biochemistry.

What does a genetic study offer?

There are panels that analyse genetic variants — known as polymorphisms — related to different metabolic pathways. One of the best-known genes is MTHFR.

Certain MTHFR variants can reduce the activity of the enzyme involved in folate metabolism and, under certain circumstances, be associated with changes in homocysteine levels.

We can also study genes such as MTR and MTRR, which are related to reactions in which vitamin B12 and the remethylation of homocysteine are involved. Another frequently included gene is COMT, which encodes an enzyme involved in the metabolism of catecholamines such as dopamine, adrenaline, and noradrenaline, among other molecules.

And here an interesting characteristic of these studies emerges: your germline genetic sequence does not change simply because you get older. If you carry a particular genetic variant today, it will still be part of your genome twenty years from now. From that perspective, therefore, it generally makes no sense to repeatedly order the same genetic study.

But be careful: genetics does not mean destiny

This is probably the most important message. Finding a genetic variant does not automatically mean that you have a disease or that you need to take a supplement for the rest of your life.

Nor can we look solely at a single COMT polymorphism and conclude that a person will experience anxiety, excess dopamine, or a particular personality type. Human biology is far more complex than that.

Genes interact with one another and, moreover, with our diet, age, microbiome, physical activity, medications, illnesses, alcohol consumption, tobacco use, and many other environmental factors.

This is precisely what distinguishes genotype from phenotype. We may be able to identify a stable genetic predisposition, but what is actually happening in our body can change constantly.

So can I know which B12 or which folate I will need for the rest of my life?

Not exactly. Genetics can provide additional information, but responsible supplementation should not be established solely on the basis of a genetic panel.

If I want to assess a patient's metabolic status, I may also need to evaluate real, modifiable parameters such as a full blood count, vitamin B12, folate, homocysteine, kidney function, liver function, diet, medications, symptoms, and clinical history. In certain situations, we can also study other specific markers.

Because knowing the genetic machinery you inherited is one thing, and knowing how your metabolism is actually functioning today is quite another.

An example: MTHFR

Finding an MTHFR variant does not mean that a person is ill. These variants are relatively common in the general population.

What is truly interesting from a clinical standpoint is understanding the context: what is the homocysteine level? Is there a folate deficiency? What is the vitamin B12 level? Is there kidney disease? What diet does the person follow? What medications do they take?

Genetics can help us understand one piece of the puzzle. But it is not the complete puzzle.

Do I recommend this type of testing?

In certain patients, these tests can indeed be interesting as a complementary tool within a broader medical or nutritional assessment.

What I do not recommend is using them as a kind of definitive manual for the body that automatically determines which supplements we should take for the rest of our lives. Nor do I recommend starting high doses of B-group vitamins simply because a genetic variant appears in a report.

More supplementation does not necessarily mean better health. For example, excessive and prolonged doses of vitamin B6 can cause neurological toxicity, and correcting folate without adequately identifying certain situations related to vitamin B12 can complicate clinical interpretation.

My approach to personalised medicine

Personalised medicine is not about running a genetic test and turning every variant into a supplement. It is about integrating genetics, laboratory results, diet, lifestyle, medical history, medication, symptoms, and clinical examination. That is where this type of information can prove truly valuable.

A genetic study can offer us a permanent snapshot of certain variants we have inherited. But our health is a film that keeps changing every day. And it is precisely for that reason that genetics can guide us, but should never replace clinical medicine.