HSA | FSA CARDS ARE NOW ACCEPTED

Last reviewed: May 12, 2026 Last updated: May 12, 2026

Written by: Jay Hastings , CEO of PlexusDx

Jay Hastings is the CEO of PlexusDx, a precision health company focused on genetic testing, blood biomarker insights, and personalized wellness recommendations. He has more than 20 years of experience across healthcare innovation, genomics, laboratory operations, healthcare investing, and strategic finance. His work has included scaling healthcare startups, leading CLIA lab integrations, and helping expand consumer access to precision health tools.

Medically reviewed by: Jayden Lee, PharmD, EMBA

Jayden Lee, PharmD, EMBA, is the PlexusDx Medical Science Liaison with a PharmD and MBA specializing in pharmacogenomics and clinical product development, with a proven ability to bridge the gap between genomic research and practical patient outcomes. Dr. Lee has more than 10 years of professional experience in clinical pharmacy, academia, and research.

Vitamin C and SLC2A14: What Your Genes May Mean for Absorption and Health

Vitamin C is an essential nutrient that functions as a potent antioxidant, supports immune health, aids collagen production, and improves iron absorption. Because the body cannot make or store vitamin C, regular dietary intake is required. The SLC2A14 gene encodes a transporter that helps move the oxidized form of vitamin C, dehydroascorbic acid, into cells. Variations in this gene can influence how efficiently vitamin C enters cells and how well your body uses it.

Why SLC2A14 matters

SLC2A14 affects cellular uptake of the oxidized form of vitamin C. When transporter function is reduced, cells may hold lower vitamin C levels even when dietary intake seems adequate. Lower cellular vitamin C can weaken antioxidant defenses and potentially increase susceptibility to inflammation and oxidative stress. Understanding your SLC2A14 genotype can help you tailor diet, supplementation, and lifestyle choices to support optimal vitamin C status.

Practical strategies to support vitamin C status

  • Diet: Prioritize vitamin C-rich whole foods every day. Top sources include citrus fruits, strawberries, kiwi, papaya, bell peppers, broccoli, Brussels sprouts, and dark leafy greens. Aim to include at least one high-vitamin C food at each meal when possible.
  • Supplementation: If dietary intake is inconsistent, consider a daily vitamin C supplement. Typical supplemental doses range from 250 mg to 1,000 mg per day depending on needs and tolerance. Talk with your healthcare provider before starting supplements, especially if you have medical conditions or take medications.
  • Timing and forms: Vitamin C is water soluble and cleared from the body; smaller, more frequent doses can maintain steadier blood levels. Liposomal vitamin C or combination formulas with bioflavonoids may enhance absorption for some people, but consult your provider for personalized guidance.
  • Iron absorption: Vitamin C enhances non-heme iron absorption from plant foods. Pair vitamin C-rich foods with iron sources if improving iron status is a goal.
  • Lower oxidative stress: Reduce behaviors that increase oxidative demand, such as smoking, excessive alcohol, poor sleep, and chronic unmanaged stress. Regular physical activity and adequate sleep support antioxidant systems.
  • Blood testing: If concerned about deficiency or ongoing inflammation, discuss testing options with your clinician. Plasma vitamin C or general nutritional panels may be used to assess status in context with clinical symptoms.

Genetic interpretations for SLC2A14 (rs12815313)

Two effect alleles (TT)

If you have the TT genotype for rs12815313, you carry two copies of the effect allele. This variation is associated with reduced efficiency of transporting dehydroascorbic acid into intestinal and other cells. As a result, your body may absorb and retain vitamin C less effectively at the cellular level, even if your dietary intake appears adequate.

Potential implications

  • Lower cellular vitamin C levels
  • Increased vulnerability to oxidative stress and inflammation
  • Possible need for closer attention to dietary and supplemental vitamin C

Practical steps

  • Increase daily intake of vitamin C-rich foods: include citrus, berries, kiwi, bell peppers, broccoli, and leafy greens.
  • Consider a daily vitamin C supplement after discussing dose and form with your healthcare provider.
  • Use split dosing to maintain steady blood levels, for example 250 mg twice daily instead of a single large dose.
  • Adopt lifestyle habits that reduce oxidative stress: quit smoking, limit excess alcohol, prioritize sleep, manage stress, and exercise regularly.
  • Discuss blood testing with your clinician if you have symptoms of deficiency or chronic inflammation.
One effect allele (CT)

If you have the CT genotype for rs12815313, you carry one copy of the effect allele. This variation may moderately reduce the efficiency of transporting dehydroascorbic acid into cells. Your primary gut transporters still support vitamin C absorption, but your cellular uptake may be somewhat lower than average.

Potential implications

  • Mildly reduced cellular vitamin C compared to non-carriers
  • Possible greater sensitivity to periods of increased oxidative stress or inflammation

Practical steps

  • Prioritize vitamin C-rich whole foods daily to provide steady intake.
  • Monitor intake consistency; consider supplements during times of increased need such as illness, high stress, or poor diet.
  • Consider smaller, frequent supplemental doses if recommended by your healthcare provider.
  • Adopt antioxidant-supporting lifestyle practices: balanced diet, regular activity, adequate sleep, and stress reduction.
No effect alleles (CC)

If you have the CC genotype for rs12815313, you carry two copies of the non-effect allele. This genotype is associated with typical function of the GLUT14 transporter and standard cellular uptake of dehydroascorbic acid. With normal transporter activity, your cells are likely able to take up vitamin C effectively when your diet provides adequate amounts.

Potential implications

  • Typical cellular vitamin C uptake given sufficient dietary intake
  • Standard antioxidant and collagen support from vitamin C when consuming an adequate diet

Practical steps

  • Continue to consume a variety of vitamin C-rich fruits and vegetables daily.
  • Use supplements only if dietary intake is inconsistent or if advised by a healthcare provider.
  • Maintain healthy lifestyle habits that preserve antioxidant balance and reduce inflammation.

Diet, supplement, and lifestyle recommendations

  • Daily diet: Aim for at least 5 servings of vegetables and 2 servings of fruit each day with a focus on high vitamin C choices like bell peppers, citrus, berries, kiwi, broccoli, and tomatoes.
  • Supplement guidance: If dietary intake is low or you have a genotype associated with reduced uptake, discuss a routine supplement with your provider. Suggested starting ranges are 250 mg to 500 mg per day, adjusted for personal needs. During illness or heightened stress, short-term increases may be considered under medical supervision.
  • Combine with other nutrients: Ensure adequate intake of other antioxidants and cofactors such as vitamin E, zinc, and a balanced intake of B vitamins to support overall antioxidant and immune function.
  • Lifestyle: Prioritize sleep, manage stress, avoid smoking, limit excessive alcohol, and stay physically active. These habits reduce oxidative load and support nutrient needs.
  • Monitoring: If you have chronic inflammation, frequent illness, or symptoms suggestive of deficiency, discuss targeted testing and monitoring with your clinician.

Important disclaimer

PlexusDx provides educational information about genetic predispositions and how they may influence health and wellness. This content is not medical advice. Always consult with your healthcare provider before making changes to your diet, supplements, or medical care. Your healthcare provider can interpret genetic findings in the context of your overall health, medications, laboratory results, and family history.

If this genetic variant is present in your PlexusDx results, the following tests and reports are commonly used to explore it further:

🧬 Genetic Tests:

🧪 Blood Tests:

📄 Genetic Report:

Frequently Asked Questions About Vitamin C and SLC2A14 rs12815313

How does the SLC2A14 rs12815313 variant affect vitamin C absorption?

The SLC2A14 gene helps move dehydroascorbic acid (the oxidized form of vitamin C) into cells. With rs12815313 effect alleles (CT or TT), transporter efficiency may be reduced, so your cells may hold less vitamin C even if your dietary intake looks sufficient.

What should I do if my rs12815313 result is TT, CT, or CC?

TT: you may absorb/retain vitamin C less effectively at the cellular level, increasing vulnerability to oxidative stress and inflammation—consider closer attention to vitamin C intake and possible supplementation with your clinician. CT: you may have a mild to moderate reduction in cellular uptake—prioritize consistent vitamin C-rich foods and consider supplements during higher-need periods. CC: typical cellular uptake is expected with adequate dietary intake—continue a vitamin C–rich diet and supplement only if intake is inconsistent or advised.

Which vitamin C diet and supplement strategies best support people with reduced cellular uptake?

Prioritize daily whole foods high in vitamin C (citrus, strawberries, kiwi, papaya, bell peppers, broccoli, Brussels sprouts, dark leafy greens) and aim to include at least one high-vitamin C food at each meal when possible. If intake is inconsistent or your genotype suggests reduced uptake, a daily vitamin C supplement may help (commonly 250–1,000 mg/day, with smaller split doses like 250 mg twice daily for steadier levels), but discuss dosing and form with your healthcare provider. Also support vitamin C through habits that lower oxidative stress (avoid smoking, limit excess alcohol, prioritize sleep, manage stress, and stay physically active), and consider related testing if you have symptoms of deficiency or chronic inflammation.

What tests can help me learn more about Vitamin C and SLC2A14 rs12815313?

The Optimal Diet and Weight Loss Genetic Test delivers over 295 genetic insights related to nutrition response, body composition, metabolism, and fitness. The Diet and Nutrition Genetic Report translates your results into personalized, actionable guidance. Your healthcare provider can also recommend targeted blood tests based on your specific pathway results and health history to complement your genetic insights with current biomarker data.

Medical and Editorial Standards

Medical review process: This article was reviewed for medical accuracy, scientific clarity, evidence alignment, and appropriate discussion of genetics, medications, supplements, biomarkers, and health-related claims.

Sources and evidence: PlexusDx educational content is developed using peer-reviewed research, clinical literature, reputable medical references, and, where applicable, public health or regulatory guidance. References are included at the end of the article when scientific, medical, or health-related claims are discussed.

Commercial transparency: PlexusDx offers genetic testing, blood biomarker testing, personalized supplement recommendations, and related precision wellness services. Product mentions are intended to help readers understand available options and should not be interpreted as medical advice.

Important disclaimer: PlexusDx educational content is for informational purposes only and should not be used as a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before making decisions about medications, supplements, genetic testing, lab testing, or health-related care.