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How Your CYP2R1 Gene Affects Vitamin D

Vitamin D is essential for bone strength, immune support, muscle function, and overall well being. Your skin makes vitamin D when exposed to sunlight, but factors like where you live, the season, and your skin color affect how much you produce. You can also get vitamin D from foods such as fatty fish, egg yolks, and fortified products.

The CYP2R1 gene encodes an enzyme called 25-hydroxylase. This enzyme performs a key first step: it converts inactive vitamin D from sunlight or diet into 25-hydroxyvitamin D, also called calcidiol. That circulating form is what clinicians measure in blood tests to assess vitamin D status. Variations in CYP2R1 can change how efficiently this conversion happens, and that can influence your typical vitamin D levels.

What Your Genotype Means

Two effect alleles (TT for rs1562902)

If your genotype is TT, you carry two copies of the effect allele. This version of CYP2R1 is associated with higher circulating 25-hydroxyvitamin D levels under similar sun exposure and dietary intake compared to other genotypes. In practical terms, your 25-hydroxyvitamin D conversion step may be more efficient, which can help support bone health, immune function, and muscle performance.

However, higher genetically influenced vitamin D levels do not remove the need to maintain healthy behaviors. Sun exposure, food intake, body composition, and other factors still contribute to your actual vitamin D status. It remains important to balance sensible sun exposure with skin protection and to consider testing if you have health concerns or risk factors for vitamin D deficiency or excess.

One effect allele (CT for rs1562902)

If your genotype is CT, you carry one copy of the effect allele. This is associated with slightly higher 25-hydroxyvitamin D levels compared to individuals without the effect allele. Your CYP2R1 enzyme may be somewhat more efficient at converting inactive vitamin D into the circulating form measured in blood tests.

This modest genetic advantage can make it easier for you to maintain adequate vitamin D under typical sun exposure and dietary patterns, but it does not guarantee optimal levels. Lifestyle factors, seasonal changes, sunscreen use, dietary choices, and body composition will still affect your vitamin D status. Regular monitoring and sensible choices will help you maintain balance.

No effect alleles (CC for rs1562902)

If your genotype is CC, you carry two copies of the non-effect allele. This genotype is associated with typical or average 25-hydroxyvitamin D levels. Your CYP2R1 enzyme functions at a standard efficiency for the first activation step of vitamin D, converting it into the circulating calcidiol measured in clinical tests.

With the CC genotype, maintaining adequate vitamin D through sensible sun exposure, eating vitamin D rich foods, and supplementing when needed is important for bone health, immune function, and overall well being. You should pay attention to other risk factors that can reduce vitamin D levels, such as limited sun exposure, darker skin, obesity, certain medications, or medical conditions that affect absorption or metabolism.

Practical Recommendations

Testing and monitoring

  • Consider a 25-hydroxyvitamin D blood test if you have symptoms of deficiency, risk factors, or are starting a higher dose supplement.
  • Typical target ranges differ by lab and guideline. Talk with your healthcare provider to interpret results and set goals based on your health history.
  • Re-test 8 to 12 weeks after starting or changing a supplement dose or after significant seasonal changes in sun exposure.

Sun exposure

  • Sensible sun exposure can help maintain vitamin D. Short periods of midday sun on arms and legs a few times per week may be sufficient for many people, but needs vary widely.
  • Balance sun exposure with skin cancer prevention. Use sun protection when exposure is prolonged and avoid intentional tanning.

Dietary suggestions

  • Include vitamin D rich foods: fatty fish (salmon, mackerel, sardines), canned tuna, egg yolks, and fortified foods such as milk, plant milks, and some cereals.
  • Pair vitamin D foods with sources of healthy fat when possible since vitamin D is fat soluble and absorbs better with dietary fat.
  • If you follow a vegetarian or vegan diet, rely on fortified foods and discuss supplementation with your healthcare provider.

Supplement guidance

Supplements can help reach adequate vitamin D levels when sun exposure and diet are insufficient. Typical forms are vitamin D3 (cholecalciferol) and D2 (ergocalciferol). D3 is more commonly used to raise blood levels.

  • Start with a standard maintenance dose if you have no deficiency and no special risk factors, but individual needs vary. Discuss dosing with your healthcare provider before starting supplements.
  • If a deficiency is found on testing, your provider may recommend a higher short term dose followed by maintenance dosing and follow up testing.
  • Avoid taking very high doses without medical supervision because excessive vitamin D can lead to elevated calcium and complications.

Lifestyle and other considerations

  • Maintain a healthy weight. Higher body fat can be associated with lower circulating vitamin D, so weight management can support overall vitamin D status.
  • Review medications and conditions with your provider. Some medications and health conditions affect vitamin D absorption or metabolism.
  • Optimize overall nutrition. Adequate magnesium and vitamin K support vitamin D function in bone and metabolic pathways, so ensure a balanced diet.

Next Steps

Use your genotype information as one piece of the picture. Genetics can influence how efficiently your body converts vitamin D, but lifestyle, environment, and health conditions are also important. Consider testing your 25-hydroxyvitamin D level if you have concerns, then discuss results and personalized dosing with your healthcare provider. If you choose to take supplements or make major lifestyle changes, follow up testing can confirm that your choices are effective and safe.

Important Disclaimer

PlexusDx provides educational information about genetic predispositions only. We do not provide medical advice, diagnose conditions, or prescribe treatments. Always consult with your healthcare provider before making changes to medications, supplements, or health routines based on genetic information. Your provider can interpret test results in the context of your personal and medical history and recommend appropriate next steps.