Vitamin C (SLC23A1)
SLC23A1 · rs33972313
Vitamin C is absorbed from the gut via the sodium-dependent transporter SVCT1. Variants in its gene SLC23A1 are the strongest known heritable predictors of circulating vitamin C and serve in studies as a lifelong marker of ascorbate exposure.
The markers
SLC23A1 encodes the sodium-dependent vitamin C transporter SVCT1, which takes up ascorbate in the gut. The missense variant rs33972313 alters transport capacity: the common G allele is associated on average with about 11 percent higher plasma ascorbate, while carriers of the rarer variant have correspondingly lower levels even at identical intake (Kobylecki 2015). A second SNP in the same gene, rs10063949, explains additional variance.
What it means
The variant describes a predisposition to somewhat lower or higher levels on the same diet. It explains why some people have low ascorbate despite a fruit-rich diet. Because rs33972313 serves as a lifelong marker of vitamin C, it is used in research for Mendelian randomization to separate cause from correlation.
Context
The genetic effect is real but moderate; diet and smoking shift the level more strongly. Genome shows the markers as technical evidence within the built-in panel 'Vitamins A–E'.
What Genome measures. The genotypes at the SLC23A1 markers rs33972313 (missense) and rs10063949.
Related topics
Sources
- 1Kobylecki et al., 2015 Genetically high plasma vitamin C and risk of ischemic heart disease: a Mendelian randomization study. American Journal of Clinical Nutrition 101:1135–1143. doi.org/10.3945/ajcn.114.104497