SLC23A2 rs3397235: Vitamin C Transport and Genetic Variation
The rs3397235 polymorphism is an intronic single-nucleotide variant located within the SLC23A2 gene on chromosome 20. This gene encodes sodium-dependent vitamin C transporter 2 (SVCT2), a primary membrane protein responsible for delivering ascorbic acid into metabolically active tissues. Research has evaluated rs3397235 for modest regulatory effects on tissue-level vitamin C distribution and systemic bioavailability, though overall clinical evidence remains limited.
What each genotype means
Typical vitamin C distribution
You carry two copies of the common C allele for SLC23A2 rs3397235. Research suggests this baseline genotype supports standard tissue-specific uptake and physiological distribution of vitamin C. Evidence linking this specific regulatory marker to systemic bioavailability differences remains limited and exploratory across diverse ancestries.
Carried by approximately 40% to 45% of individuals globally, making it the most frequent genotype across many ancestry groups.
Intermediate vitamin C transport
You carry one copy of the T regulatory allele in SLC23A2. Observational studies suggest heterozygous individuals may display subtle alterations in cellular ascorbic acid transport and tissue distribution. However, clinical evidence connecting this single variation to overall vitamin C deficiency or distinct health endpoints is preliminary and inconsistent.
Found in approximately 45% of individuals across global populations.
Altered ascorbic acid transport
You carry two copies of the less common T allele in the SLC23A2 vitamin C transporter gene. Published nutrigenomic literature associates this genotype with modest shifts in ascorbic acid uptake and cellular distribution dynamics. Current scientific findings remain limited, so these statistical associations do not imply a clinical deficiency or require targeted intervention.
Carried by roughly 10% to 15% of people worldwide, reflecting the ~0.35 global frequency of the T allele.
Genomic Context and Biology of SLC23A2
The SLC23A2 gene resides on chromosome 20 and encodes solute carrier family 23 member 2, also widely known as sodium-dependent vitamin C transporter 2 (SVCT2). Unlike its close paralog SVCT1, which is predominantly expressed in the epithelial tissues of the intestines and renal tubules to handle gross absorption and reabsorption, SVCT2 is expressed across a broad variety of tissues throughout the body. It delivers ascorbic acid directly into metabolically demanding environments, including the brain, heart, eyes, bones, and endocrine glands. The single-nucleotide polymorphism rs3397235 is situated within an intronic region of the gene. Intronic variants do not directly alter the amino acid sequence of the transporter protein; instead, researchers hypothesize that they may act as regulatory markers that influence transcript splicing efficiency, promoter interactions, or gene expression levels.
Nutrigenomic Evidence and Systemic Bioavailability
Nutrigenomics research has investigated whether common variants in SLC23A2, including rs3397235, modify tissue distribution and circulating plasma concentrations of vitamin C. While genome-wide association studies (GWAS) routinely highlight SLC23A1 variants as primary determinants of circulating blood ascorbate, SLC23A2 variants are more frequently linked to tissue-specific transport dynamics and downstream cellular antioxidant capacity. Studies examining rs3397235 and nearby linked markers have reported minor statistical variations in ascorbic acid homeostasis and modest shifts in susceptibility to oxidative stress phenotypes. However, the evidence supporting a direct, standalone biological effect for rs3397235 remains limited and exploratory. Findings frequently vary across cohorts depending on baseline dietary intake, and many observed associations fail to achieve strict genome-wide statistical significance without taking broader haplotypes or environmental factors into account.
Population Frequency and Genetic Diversity
The rs3397235 variant involves an allele substitution with a global minor allele frequency of approximately 0.35. According to aggregate population databases like dbSNP and the 1000 Genomes Project, the variant is common across diverse continental populations, though exact allele and genotype proportions vary noticeably by geographic ancestry. The homozygous major genotype is present in nearly half of individuals in many studied groups, while the heterozygous genotype is carried by roughly 40% to 45% of individuals, and the homozygous minor genotype is found in approximately 10% to 15%. Because the variant is common and naturally occurring, carrying one or two copies of the minor allele is considered a standard human genetic difference rather than a pathogenic or deleterious defect.
Translating Research to Daily Nutrition
It is critical to distinguish between exploratory nutritional genetics and definitive clinical diagnostic markers. The rs3397235 variant does not diagnose vitamin C deficiency, scurvy, or any known clinical disorder. Genetic markers in SLC23A2 account for only a small fraction of the variability in how the human body processes ascorbic acid. The primary drivers of vitamin C status remain dietary intake, lifestyle factors such as smoking or alcohol consumption, systemic inflammation, and general physiological demands. Readers should not use their rs3397235 genotype to self-prescribe mega-dose vitamin C supplements. Meeting standard dietary reference intakes through whole foods—such as citrus fruits, bell peppers, berries, and leafy greens—remains the recommended strategy, and any major dietary modifications should be discussed with a registered dietitian or physician.
How common is this variant?
The rs3397235 variant exhibits a global minor allele frequency of approximately 0.35, making it a common polymorphism across major human populations. Homozygotes for the minor allele occur in roughly 10% to 15% of individuals worldwide, with heterozygous carriers comprising approximately 40% to 45% of populations.
Frequently asked questions
What is the function of the SLC23A2 gene?
SLC23A2 provides the genetic blueprint for sodium-dependent vitamin C transporter 2 (SVCT2). This protein acts as a molecular gateway that moves ascorbic acid across cell membranes into internal tissues, including the brain, eyes, and endocrine organs.
Does having the rs3397235 minor allele mean I have a vitamin C deficiency?
No. The rs3397235 variant is a common, non-pathogenic regulatory marker that does not cause vitamin C deficiency or scurvy. Dietary intake of ascorbic acid has a far greater impact on your vitamin C levels than this single genetic variant.
Should I take high-dose vitamin C supplements if I carry rs3397235?
No scientific guidelines recommend high-dose supplementation solely based on this genetic polymorphism. Most individuals can comfortably meet their physiological vitamin C requirements through a balanced diet rich in fruits and vegetables, and any supplementation should be reviewed with a healthcare provider.
How strong is the scientific evidence linking rs3397235 to health outcomes?
The current scientific evidence is limited and exploratory. While researchers have identified associations between SLC23A2 variations and markers of oxidative balance or plasma levels, findings have not been uniformly replicated across diverse clinical trials.
Sources & further reading
Educational information only, last refreshed 9/10/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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