SLC23A1 rs2188175: Vitamin C Transport and Levels
The genetic variant rs2188175 is a single nucleotide polymorphism located in the SLC23A1 gene, which encodes the primary active transporter responsible for absorbing vitamin C across epithelial tissues. Research suggests that alleles at this locus can influence circulating ascorbic acid concentrations per unit of dietary vitamin C consumed. Evidence evaluating this specific marker remains limited, indicating that lifestyle and diet are still the primary drivers of nutritional status.
What each genotype means
Typical vitamin C absorption
You carry two copies of the common C allele in the SLC23A1 gene. Research indicates this genotype is associated with standard functioning of the sodium-dependent vitamin C transporter 1 (SVCT1) and typical circulating ascorbic acid levels relative to dietary vitamin C intake. Evidence linking variations at this locus to altered vitamin C dynamics is limited, and this genotype reflects the standard baseline seen in population cohorts.
Carried by approximately 84% to 86% of individuals of European ancestry, representing the most common genotype across most global populations.
Moderately reduced vitamin C levels
You carry one copy of the minor T allele associated with altered function of the SLC23A1 vitamin C transporter. Observational research suggests individuals with one copy of this allele may exhibit lower circulating plasma ascorbic acid concentrations per unit of dietary vitamin C consumed compared to non-carriers. Because evidence strength is limited and effect sizes can vary based on overall nutritional intake, these population-level associations do not constitute a clinical deficiency.
Carried by roughly 14% to 15% of people of European ancestry; less frequently observed in East Asian and African populations.
Reduced vitamin C accumulation
You carry two copies of the less common T allele in the SLC23A1 gene. In published research, this genotype has been linked to the greatest reduction in circulating ascorbic acid levels relative to dietary vitamin C intake, likely due to diminished SVCT1 transporter activity. However, evidence remains limited and primarily derived from European study cohorts, meaning personal nutrition and lifestyle factors play a dominant role in overall vitamin C status.
Carried by less than 1% of individuals of European ancestry and rare in most non-European populations.
What Is rs2188175 and Where Is It Located?
The variant rs2188175 is an intronic single nucleotide polymorphism situated on chromosome 5 within the SLC23A1 gene. As indexed in dbSNP, this polymorphism involves a base substitution between thymine (T) and cytosine (C). Because it sits in a non-coding region of the gene, rs2188175 does not alter the amino acid sequence of the transporter protein directly. Instead, geneticists evaluate whether variants like rs2188175 act as regulatory elements—modulating how the gene is transcribed—or serve as proxy markers in linkage disequilibrium with other functional variants within the SLC23A1 genomic region. While non-coding variants can sometimes subtly alter gene expression, they often act simply as statistical flags in association studies rather than primary molecular drivers.
The Biological Role of SLC23A1 and SVCT1
The SLC23A1 gene provides instructions for building sodium-dependent vitamin C transporter 1 (SVCT1). This specialized transport protein mediates the electrogenic uptake of L-ascorbic acid, commonly known as vitamin C, from epithelial borders. Unlike most mammals, humans lack the enzyme gulonolactone oxidase and cannot biosynthesize vitamin C internally, making dietary intake essential. SVCT1 is concentrated heavily on the brush border of enterocytes in the small intestine and in the proximal tubules of the kidneys. In these tissues, SVCT1 transports dietary vitamin C into systemic circulation and recaptures filtered vitamin C from urine to prevent excessive loss, maintaining whole-body ascorbic acid homeostasis.
Current Scientific Evidence and Vitamin C Associations
Nutrigenomic investigations have examined variation across the SLC23A1 locus to understand why people consuming similar diets exhibit varying circulating vitamin C levels. Published research has linked SLC23A1 polymorphisms to decrements in circulating plasma ascorbic acid relative to dietary intake. However, the direct evidence linking rs2188175 specifically to this outcome is classified as limited. Much of the stronger literature at this locus centers on missense variants such as rs33972313, which has shown clearer genome-wide associations with lower baseline plasma concentrations. Because linkage disequilibrium varies across populations, the statistical associations observed for rs2188175 may reflect proximity to other functional changes rather than an independent biological effect.
Population Frequency and Allelic Distribution
The frequency of rs2188175 alleles varies considerably depending on ancestral background. In European populations, the minor allele (C) displays an estimated frequency of approximately 0.08, meaning roughly 8% of chromosomes carry this variant. This distribution makes heterozygosity relatively uncommon and homozygous minor genotypes rare in populations of European descent. Across broader global databases, such as gnomAD and the 1000 Genomes Project, allele frequencies at the SLC23A1 locus fluctuate across African, Asian, and Hispanic cohorts. Because human dietary adaptations and regional genetic drift differ across the globe, nutrigenomic associations identified in one ancestral background cannot be assumed to carry identical magnitude or significance in another.
Practical Implications for Diet and Health
Learning your rs2188175 genotype does not provide a medical diagnosis of vitamin C deficiency, scurvy, or any metabolic disease. Genetic predisposition represents only a minor component of circulating micronutrient levels; daily dietary intake, smoking status, systemic inflammation, and metabolic stress exert far more substantial effects on ascorbic acid availability. Individuals carrying alleles associated with reduced transport efficiency do not necessarily need high-dose supplementation. Relying on diverse, vitamin C-rich whole foods—such as citrus fruits, bell peppers, berries, and cruciferous vegetables—is the gold standard for meeting nutritional requirements. Any concerns regarding nutritional deficiencies or supplement safety should be addressed directly with a physician or registered dietitian.
How common is this variant?
In European populations, the minor allele frequency of rs2188175 is approximately 0.08, with homozygous minor carriers representing less than 1% of the cohort. Frequencies vary across non-European continental ancestries in global genomic databases.
Frequently asked questions
Can rs2188175 cause vitamin C deficiency or scurvy?
No, this genetic variant does not cause scurvy or clinical vitamin C deficiency on its own. It is a common polymorphism associated with minor statistical variations in how efficiently vitamin C is absorbed or transported. Dietary consumption of ascorbic acid remains the determining factor in preventing deficiency.
Should I take high-dose vitamin C supplements if I carry the minor allele?
No specific evidence supports taking mega-dose vitamin C supplements based on an rs2188175 result. Standard dietary recommendations from health authorities provide sufficient vitamin C for the vast majority of individuals regardless of genotype. Consult a doctor or registered dietitian before starting any high-dose supplementation regimen.
How does the SLC23A1 gene affect vitamin C in the body?
SLC23A1 codes for the SVCT1 protein, which moves ascorbic acid across cells in the intestinal tract and kidney tubules. This process enables the body to absorb vitamin C from digested food into the blood and reclaim it from filtered fluid before it is excreted in urine.
Is the scientific evidence for rs2188175 conclusive?
No, current evidence linking rs2188175 specifically to altered vitamin C levels is considered limited. Most confirmed associations at this genetic locus center around other markers, such as the missense variant rs33972313, meaning rs2188175 may only reflect statistical linkage in certain populations.
Sources & further reading
Educational information only, last refreshed 9/14/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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Functional polymorphism in the sodium-dependent vitamin C transporter 1 gene affecting circulating ascorbic acid levels.
This variant in the primary renal and intestinal sodium-dependent vitamin C transporter gene significantly modulates circulating ascorbic acid concentrations.