You take a multivitamin every morning. So does your coworker, your neighbor, and about half the adults in most Western countries. Same pill, same doses, same assumption: that everyone needs the same amounts of the same nutrients.

But your body isn’t everyone’s body. And your genes have quite a lot to say about how you process the vitamins you swallow.

What is nutrigenomics?

Nutrigenomics is the study of how genetic variation affects the way your body interacts with nutrients. It sits at the intersection of nutrition science and genomics, and it’s built on a straightforward idea: the enzymes, transport proteins, and receptors that handle vitamins in your body are all encoded by genes. When those genes carry certain variants, the proteins they produce may work differently.

This doesn’t mean your genes “decide” whether a vitamin works for you. It means they influence the efficiency of specific metabolic steps. Some people convert beta-carotene to vitamin A quickly. Others don’t. Some people activate vitamin D efficiently. Others need more of it to reach the same blood levels. These aren’t hypothetical differences. They’re measurable, well-documented, and backed by large-scale genetic association studies.

The practical implication? A recommended daily allowance (RDA) is a population average. It’s useful as a baseline, but it wasn’t designed with your specific genetic profile in mind.

Folate and MTHFR: the most studied gene-nutrient connection

If you’ve spent any time reading about genetics and nutrition, you’ve probably encountered MTHFR. It’s the most widely discussed nutrigenomic gene for good reason.

MTHFR encodes an enzyme called methylenetetrahydrofolate reductase, which converts dietary folate (vitamin B9) into its active form, 5-methyltetrahydrofolate. This active form is essential for DNA synthesis, methylation reactions, and keeping homocysteine levels in check.

The variant rs1801133 (known as C677T) is one of the most studied SNPs in human genetics. The T allele causes an amino acid substitution (Ala222Val) that makes the enzyme thermolabile, meaning it loses stability at body temperature. Heterozygotes (one copy of the T allele) show roughly 35% reduced enzyme activity. Homozygotes (two copies) show around 70% reduced activity.

A second variant, rs1801131 (A1298C), reduces enzyme activity by about 15-20% per copy. It’s less impactful on its own, but people who carry one copy of each variant (compound heterozygotes) can experience clinically meaningful reductions in folate metabolism.

What does this mean in practice? If you carry these variants, the standard RDA for folate might not produce optimal methylation for you. Research suggests the effect is modifiable by folate intake, which is why this is one of the clearest examples of a gene-nutrient interaction with actionable potential.

About 10% of Europeans are homozygous (TT) for the C677T variant, with even higher frequencies in Hispanic and Latino populations.

Vitamin D: it’s not just about sunlight

Most people think of vitamin D as the “sunshine vitamin.” Get enough sun, and you’re covered. But your genes affect nearly every step of the vitamin D pathway, from synthesis in the skin to transport in the blood to activation in the liver and kidneys.

Synthesis: The variant rs12785878, near the DHCR7 gene, affects how efficiently your skin converts 7-dehydrocholesterol into vitamin D3 when exposed to UV light. Some people simply produce less vitamin D from the same amount of sun exposure.

Transport: Two variants in the GC gene (which encodes vitamin D binding protein) have substantial effects on circulating vitamin D levels. rs4588 (Thr436Lys) alters the binding protein’s affinity for vitamin D3. rs7041 (Asp432Glu) affects the protein’s concentration. A third variant, rs2282679, is one of the top GWAS hits for 25(OH)D levels and influences vitamin D binding and transport. Together, these GC variants determine your overall vitamin D binding capacity.

Activation: Two variants in CYP2R1 (rs10741657 and rs2060793) affect the liver enzyme responsible for the first hydroxylation step that activates vitamin D.

Receptor function: The VDR gene encodes the vitamin D receptor itself. Four well-studied variants (rs2228570/FokI, rs1544410/BsmI, rs731236/TaqI, rs7975232/ApaI) influence receptor activity and expression. The FokI variant is particularly interesting: the T allele creates a shorter, more active VDR protein that affects calcium homeostasis and immune function.

Degradation: rs6013897, near CYP24A1, affects how quickly your body breaks down active vitamin D. If you degrade it faster, you may need higher intake to maintain adequate levels.

This is why two people with identical diets, identical sun exposure, and identical supplement regimens can have very different vitamin D blood levels. Their genes are running different versions of the same metabolic pathway.

Vitamin B12 and FUT2: the gut connection

Vitamin B12 absorption isn’t just about how much you eat. It depends partly on what’s happening in your gut, and that’s where the FUT2 gene comes in.

FUT2 determines your “secretor status,” which controls whether you express certain antigens on the surface of your gut mucosa. The variant rs601338 is a nonsense mutation (W154X) that eliminates FUT2 function entirely. About 20% of Europeans are non-secretors (carrying two copies of the A allele).

Non-secretor status has a well-documented effect on B12 absorption and gut microbiome composition. A linked variant, rs602662, shows up in GWAS studies as significantly associated with circulating B12 levels. Your secretor status also affects colonization by Bifidobacterium species, which play a role in B-vitamin production in the gut.

So if you’ve ever wondered why some people maintain healthy B12 levels easily while others struggle despite adequate dietary intake, FUT2 variants are one piece of that puzzle.

Vitamin A and BCMO1: the beta-carotene conversion problem

Here’s a scenario: you eat plenty of sweet potatoes, carrots, and leafy greens, all rich in beta-carotene. You assume you’re getting enough vitamin A. But your body might be converting only a fraction of that beta-carotene into usable retinol.

The BCMO1 gene encodes beta-carotene 15,15’-monooxygenase, the enzyme responsible for cleaving beta-carotene into retinol (active vitamin A). Two variants significantly affect this conversion:

rs12934922 (A267S): Reduces BCMO1 enzyme activity by approximately 30%. The T allele appears in about 45% of the population.
rs7501331 (R267S): Further reduces conversion efficiency. When both variants are present together, beta-carotene conversion can drop by up to 69%.

This matters most for people who rely on plant-based sources for their vitamin A. If you’re a low converter, you may need preformed vitamin A (retinol, found in animal products) rather than relying on beta-carotene from vegetables.

It’s worth noting that standard blood tests for vitamin A don’t distinguish between people who convert beta-carotene efficiently and those who don’t. Genetic data fills that gap.

Why one-size-fits-all doesn’t work

Recommended daily allowances were developed by studying large populations and finding averages. They’re a solid starting point. But averages, by definition, don’t describe any individual perfectly.

When you layer genetic variation on top of dietary differences, gut health, lifestyle factors, and environmental exposures, the picture gets complex quickly. Someone with MTHFR C677T TT genotype, poor VDR receptor variants, and low BCMO1 conversion has a very different nutritional landscape than someone without those variants.

This isn’t about rejecting conventional nutrition advice. It’s about adding a layer of personalization. The RDA tells you what the average person needs. Your genetics can tell you where you might differ from that average.

Practical takeaways

Before you overhaul your supplement cabinet, a few things to keep in mind:

Genetics is one factor, not the whole story. Your diet, gut health, sun exposure, age, medications, and dozens of other variables all matter. A genetic variant that reduces enzyme activity by 30% doesn’t automatically mean you’re deficient. It means you might benefit from paying closer attention to that nutrient.

Talk to a healthcare provider. Genetic data gives you context, not clinical directives. If your results suggest reduced folate metabolism or vitamin D processing, that’s a conversation starter with your doctor, not a prescription.

Blood work complements genetic data. Genetics tells you about predispositions. Blood work tells you what’s actually happening right now. The combination is more useful than either alone.

Quality of interpretation matters. A raw list of SNPs without context isn’t actionable. What matters is how variants are cross-referenced against published research, how the evidence is scored, and whether the interpretation accounts for gene-gene interactions.

Where SoDNAscan fits in

SoDNAscan analyzes your raw DNA file across 256 carefully selected SNPs, including the nutrigenomic variants discussed in this article: MTHFR (rs1801133, rs1801131), VDR (rs2228570, rs1544410, rs731236, rs7975232), GC (rs4588, rs7041, rs2282679), FUT2 (rs601338, rs602662), BCMO1 (rs12934922, rs7501331), and supporting variants in CYP2R1, CYP24A1, DHCR7, MTR, MTRR, and ALPL.

Every finding is confidence-scored based on the strength of the underlying research. The result is a personalized health book that explains what published studies say about your specific genetic variants, presented in plain language with evidence ratings you can actually evaluate.

Your genes don’t change. But understanding what they say about your nutritional needs can change how you approach your health.

Genetic Nutrition: How Your Genes Affect Your Vitamin Needs