SLC23A1 rs1144868: Vitamin C Absorption and Genetics
rs1144868 is a single nucleotide polymorphism located in the SLC23A1 gene, which encodes the sodium-dependent vitamin C transporter SVCT1. Scientific studies have linked variation at this genomic locus to subtle shifts in circulating plasma concentrations of L-ascorbic acid. While it plays a functional role in nutrigenomics, overall vitamin C status remains heavily driven by dietary intake and lifestyle.
What each genotype means
Baseline Vitamin C Transporter Status
Research suggests that carrying two copies of the A allele is associated with typical function of the SVCT1 vitamin C transporter and baseline circulating ascorbic acid concentrations. Observational studies have evaluated this locus in relation to dietary vitamin C intake and serum micronutrient status without finding an inherent predisposition toward reduced baseline absorption. Because nutritional status depends heavily on overall diet, individuals with this genotype generally maintain standard circulating levels given adequate dietary intake.
Carried by approximately 45% to 50% of individuals of European and admixed American ancestries, and is the predominant genotype across most global populations.
Moderately Reduced Vitamin C Concentration
Carrying one copy of the G allele has been associated in observational studies with modest variations in circulating vitamin C concentrations, reflecting slightly lower transport capacity via SVCT1. However, the evidence supporting clinical effects remains limited, and variations in everyday dietary intake typically outweigh this genetic effect. Maintaining a diet rich in fruits and vegetables is standard for supporting optimal plasma ascorbic acid levels.
Found in approximately 40% to 45% of European and admixed American populations, where the G allele has an estimated frequency of 0.30.
Lower Circulating Vitamin C Tendency
Individuals carrying two copies of the G allele may have a statistical tendency toward lower systemic ascorbic acid concentrations due to altered SVCT1-mediated renal reabsorption or intestinal uptake. Published evidence for this specific variant remains limited and largely restricted to population-level associations, meaning it does not cause severe deficiency on its own. Ensuring adequate daily dietary intake of vitamin C can help mitigate potential variations in transporter efficiency.
Carried by roughly 8% to 10% of individuals in European and admixed American cohorts, but occurs at differing rates across other global ancestries.
Genetic Location and Molecular Biology of SLC23A1
The single nucleotide polymorphism rs1144868 resides within the SLC23A1 gene, located on chromosome 5. SLC23A1 encodes the sodium-dependent vitamin C transporter 1, commonly abbreviated as SVCT1. This transport protein is primarily expressed on the epithelial brush border membranes of the small intestine, liver, and renal proximal tubules. Biochemically, SVCT1 utilizes the electrochemical sodium gradient across cell membranes to actively translocate L-ascorbic acid into the bloodstream and reclaim it during renal filtration. Because humans cannot synthesize ascorbic acid endogenously due to lack of the functional enzyme gulonolactone oxidase, maintaining whole-body ascorbate homeostasis is entirely reliant on dietary ingestion coupled with the active transport and reabsorption orchestrated by SLC23A1.
Nutrigenomic Evidence and Plasma Ascorbic Acid
Nutrigenomic research evaluates how inherited variations affect individual nutrient kinetics. Multiple observational cohorts and genome-wide exploration efforts have analyzed SLC23A1 variants for their correlation with circulating plasma vitamin C levels. Studies, such as population-level analyses reported in the [American Journal of Clinical Nutrition](https://pubmed.ncbi.nlm.nih.gov/20519558/), demonstrate that variation across the SLC23A1 locus accounts for modest differences in circulating ascorbate. While variants like rs33972313 have established strong statistical associations, broader variation within the locus, including rs1144868, demonstrates limited-to-moderate evidence in modulating baseline plasma concentrations. These variants appear to subtly alter transporter capacity or renal clearance kinetics, meaning that two individuals consuming identical diets may display slight differences in circulating ascorbate.
Population Distribution and Genetic Diversity
Allele frequencies for rs1144868 vary across global ancestral backgrounds. In populations of European and admixed American descent, the minor allele maintains a frequency of approximately 0.30. In contrast, East Asian and African populations often exhibit differing allele distributions, demonstrating the regional evolution of micronutrient handling. Because nutrigenomic association studies have historically enrolled cohorts dominated by European ancestry, caution is warranted when extrapolating specific effect sizes to other demographic backgrounds. Population-level databases such as [dbSNP](https://www.ncbi.nlm.nih.gov/snp/rs1144868) track these regional disparities, emphasizing that inherited differences in nutrient transporters are normal human variations rather than pathogenic mutations.
Translating Variant Information into Daily Wellness
Carrying an allele associated with lower circulating vitamin C does not represent an inherited metabolic disease, nor does it guarantee clinical deficiency or scurvy. Genetics provides a baseline window into transport capacity, but external factors such as dietary intake, tobacco use, systemic inflammation, and metabolic stress exert a vastly larger influence on real-world plasma ascorbic acid. Anyone interested in optimizing their nutritional status can do so primarily through a colorful, nutrient-dense diet rich in citrus, bell peppers, berries, and cruciferous vegetables. Genetic results should never replace standard clinical biomarkers or medical advice; individuals contemplating high-dose vitamin C supplementation or exploring nutrient interactions should consult a qualified physician or registered dietitian.
How common is this variant?
The minor allele maintains an estimated frequency of approximately 0.30 in European and admixed American populations according to public reference panels. Frequencies vary across other global ancestral groups.
Frequently asked questions
Does having rs1144868 mean I will develop a vitamin C deficiency?
No, having this genetic variant does not mean you will develop a vitamin C deficiency or scurvy. The variant is associated only with modest statistical differences in how efficiently vitamin C is handled, and normal dietary intake typically meets the body's requirements.
What is the function of the SLC23A1 gene?
The SLC23A1 gene produces the SVCT1 protein, a sodium-coupled transporter found mainly in the kidneys and intestine. It enables the active absorption of vitamin C from digested food and prevents excessive loss by reabsorbing vitamin C in the renal tubules.
Should I take high-dose vitamin C supplements if I carry the variant?
Genetic results alone should not dictate high-dose supplementation. Most people easily achieve adequate plasma ascorbic acid through a varied diet containing fruits and vegetables. Any decisions regarding high-dose dietary supplements should be discussed with a healthcare provider.
How reliable is the scientific evidence linking rs1144868 to vitamin C levels?
The scientific evidence linking this specific SNP to plasma vitamin C levels is classified as limited to moderate. While the SLC23A1 gene itself clearly plays an essential role in ascorbate transport, the precise clinical significance of rs1144868 varies across studies and ancestry groups.
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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Functional polymorphism in the sodium-dependent vitamin C transporter 1 gene affecting circulating ascorbic acid levels.
Transporter polymorphism associated with significant decrements in circulating ascorbic acid levels per unit of dietary vitamin C consumed.