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Vitamin C and your genes: what to know

Vitamin C is essential for tissue repair, immune health, antioxidant protection, and iron absorption. Because the body cannot make vitamin C, you must get it from food or supplements. The SLC23A2 gene encodes the SVCT2 transporter protein that moves vitamin C into cells throughout your body. Variations in this gene can change how efficiently cells take up vitamin C, which may affect tissue levels even when dietary intake appears adequate.

How SLC23A2 variation affects vitamin C biology

The SLC23A2 gene produces the SVCT2 transporter responsible for cellular vitamin C uptake. Differences at the rs1279683 location of SLC23A2 change transporter efficiency. Less efficient transport can mean lower vitamin C inside cells, which can reduce collagen production, antioxidant defense, and other vitamin C–dependent processes. Understanding your genotype can help you tailor diet, supplementation, and lifestyle choices to support healthy vitamin C status.

Genetic interpretation (rs1279683)

AA — two effect alleles (reduced cellular vitamin C uptake)

The AA genotype is associated with reduced efficiency of the SVCT2 transporter. This can lead to lower cellular and tissue vitamin C concentrations even with normal dietary intake. Key considerations:

  • Prioritize consistent intake of vitamin C rich foods daily.
  • Consider a supplement if dietary intake is low or if you have increased needs.
  • Limit tobacco exposure and other environmental pollutants that raise vitamin C demand.
  • Discuss plasma vitamin C testing and personalized dosing with your healthcare provider.
AG — one effect allele (likely reduced cellular vitamin C uptake)

The AG genotype is associated with a likely modest reduction in SVCT2 function. Cells may take up vitamin C less efficiently than those without the effect allele. Key considerations:

  • Emphasize vitamin C–rich foods every day to maintain tissue levels.
  • Supplementation may help when diet is inconsistent or demands are higher.
  • Minimize smoking and heavy pollutant exposure to reduce extra vitamin C use.
  • Talk with your healthcare provider about checking vitamin C status if you have symptoms or risk factors.
GG — zero effect alleles (typical cellular vitamin C uptake)

The GG genotype is associated with normal SVCT2 transporter function and typical cellular uptake of vitamin C. With a balanced diet you are likely able to achieve healthy tissue vitamin C levels. Key considerations:

  • Maintain a diet with vitamin C sources like citrus, berries, bell peppers, broccoli, and leafy greens.
  • A general adult intake goal is 75 to 90 mg per day unless advised otherwise by a provider.
  • Consider short-term supplementation during illness, high stress, or periods of low dietary intake.

Diet recommendations

  • Eat a variety of vitamin C rich fruits and vegetables daily: citrus, strawberries, kiwifruit, bell peppers, broccoli, Brussels sprouts, and leafy greens.
  • A single medium orange or a cup of strawberries provides roughly 60 to 90 mg of vitamin C; combine sources across the day for steady intake.
  • Include raw or lightly cooked produce when possible because vitamin C is sensitive to heat and prolonged storage.
  • For those with the AA or AG genotype, focus on consistent intake at meals and snacks rather than relying on occasional high-dose foods.

Supplement recommendations and considerations

  • Supplements can help maintain tissue vitamin C when diet alone is inadequate or when needs are higher.
  • Common supplemental doses range from 100 mg to 500 mg daily for general support; some individuals or clinical situations use higher short-term dosing. Discuss appropriate dose with your healthcare provider.
  • Split daily doses (for example, morning and afternoon) may improve steady blood levels because vitamin C is water soluble and excess is excreted.
  • Choose reputable supplement brands and check for product quality. If you have kidney disease or are prone to kidney stones, consult your provider before starting supplementation.

Lifestyle recommendations

  • Avoid smoking and reduce exposure to secondhand smoke; tobacco increases oxidative stress and depletes vitamin C.
  • Minimize exposure to pollutants and heavy environmental oxidative stress when possible; use masks or air filters if needed in high-exposure settings.
  • Manage chronic stress, get adequate sleep, and maintain regular physical activity—these supports reduce overall nutrient demand and help recovery.
  • If you have inflammatory or chronic illnesses that increase oxidative stress, discuss monitoring and nutrient strategies with your provider.

Blood tests and monitoring

  • Plasma vitamin C testing can identify low circulating levels, but tissue levels may differ due to transporter efficiency. Discuss testing indications with your healthcare provider.
  • If low levels are detected, your provider may recommend dietary changes, supplementation, or repeat testing after intervention.
  • Keep a record of dietary intake, symptoms, and any supplements to share with your provider for personalized guidance.

When to talk with your healthcare provider

  • If you have symptoms suggestive of vitamin C deficiency such as unusual fatigue, bruising, slow wound healing, or bleeding gums.
  • If you have medical conditions that increase nutrient needs or impair absorption, such as chronic inflammatory disease, malabsorption, or recent surgery.
  • If you are pregnant or breastfeeding and want personalized vitamin C recommendations.
  • If you are considering high-dose vitamin C supplementation or intravenous vitamin C therapies.

PlexusDx provides genetic information to help you understand potential influences on vitamin C status and health. This information is educational only and is not medical advice. Always consult your healthcare provider before starting or changing diet, supplements, medications, or medical care.