Your Sunshine Genes: One Sun, Different Outcomes

●       Five key genes (DHCR7, CYP2R1, GC, CYP24A1, VDR) govern how efficiently the body makes, transports, and uses vitamin D - explaining why two people in the same sun end up with different levels,per co-founders Dr. Karrow and Dr. Mallard.

●       Genetic variation can roughly double deficiency risk between the least and most favourable gene combinations, and also sorts people into low, medium, or high responders to the same supplement dose.

●       Since genes can't be changed but their effect can be measured, the recommended path is test (Vitamin D Test Kit) → supplement (ImmunoDrops D3+K2) → retest at12 weeks to see your true response pattern.

Two people can share the exact same sun-soaked afternoon but end up with completely different vitamin D levels. The explanation lies hidden inside your DNA.

"Environmental variables such as sunlight exposure, diet and supplementation influence vitamin D levels, but genetics predetermines an individual person's status."

— Dr. Niel A. Karrow, Ph.D., Co-Founder

Making Vitamin D is Only Step One

UVB light hitting your skin is just the starting trigger. To become useful, that initial compound must travel through your blood, transform inside your liver, convert again inside your kidneys, and dock onto receptors on your cells.

The 5 Key Genes Driving Your Levels

Ordinary, widespread genetic variations shape how well your body handles this complex pathway. Four of the five genes below are covered in detail in a 2025 review of vitamin D genetics co-authored by ImmunoCeutica's founding scientists:

• DHCR7: Controls the initial ingredient supply in your skin.
• CYP2R1: Regulates the main liver enzyme creating storage vitamin D.
• GC: Codes for the carrier protein moving vitamin D through blood.
• CYP24A1: Governs how fast your body breaks down and clears it.
• VDR: Determines how effectively your cells accept the final hormone.

How Much Do These Genes Matter?

They matter immensely. A large-scale genome-wide study found that people carrying the least favourable combination of these variants are about twice as likely to fall short compared with those carrying the most favourable combination. Twin studies confirm that a significant portion of your vitamin D status is inherited.

Your genes also shape your response to supplements. Clinical trials show that the exact same daily dose can produce very different blood levels from one person to the next, sorting people into low, medium, or high responders. You can't guess your category by looking in the mirror.

What You Can Actually Do About It

You can't change your genes — but you can find out what they're doing to your vitamin D level, and that's entirely within reach. Because so much of your response is written into your DNA, guessing gets you nowhere. Measuring is the only way to know where you actually stand.

"Since hundreds of genes and various lifestyle factors control vitamin D metabolism and concentrations in the blood, it is impossible to predict individual level without testing. Our experience shows without precision testing, it is just guessing."

— Dr. Bonnie A. Mallard, Ph.D., Co-Founder

The approach is simple, and it works with your genetics rather than against them:

1. Test your baseline. The Vitamin D Test Kit measures your level at home — no lab visit required.
2. Supplement to match your needs. Pair your results with ImmunoDrops D3+K2.
3. Retest at 12 weeks. Levels take that long to stabilize after any change, so this is when you'll see your true response — the low, medium, or high responder pattern your genes were driving all along.

Your genetics pull the strings behind the scenes. Testing is how you finally see them.

The Vitamin D Test Kit measures your level at home, no lab visit required. Pair it with ImmunoDrops D3+K2, then retest at 8 to 12 weeks to confirm where you have landed.

References

1. Karrow NA, Leuschner SE, Shandilya UK, Mallard BA, Wagter-Lesperance L, Bridle BW. Genetic Variants Influencing Individual Vitamin D Status. Nutrients. 2025;17(16):2673.
2. Voltan G, Cannito M, Ferrarese M, Ceccato F, Camozzi V. Vitamin D: An Overview of Gene Regulation, Ranging from Metabolism to Genomic Effects. Genes. 2023;14(9):1691.
3. Wang TJ, Zhang F, Richards JB, et al. Common genetic determinants of vitamin D insufficiency: a genome-wide association study. Lancet. 2010;376(9736):180-188.
4. Barry EL, Rees JR, Peacock JL, et al. Genetic variants in CYP2R1, CYP24A1, and VDR modify the efficacy of vitamin D3 supplementation for increasing serum 25-hydroxyvitamin D levels in a randomized controlled trial. J Clin Endocrinol Metab. 2014;99(10):E2133-E2137.