Vitamin C transporter gene polymorphisms, dietary vitamin C and serum ascorbic acid

Background/Aims: Vitamin C transporter proteins SVCT1 and SVCT2 are required for the absorption and transport of vitamin C in humans. This study aims to determine whether common SVCT genotypes modify the association between dietary vitamin C and serum ascorbic acid. Methods: Non-smoking men and women (n = 1,046) aged 20-29 were participants of the Toronto Nutrigenomics and Health Study. Overnight fasting blood samples were collected to determine serum ascorbic acid concentrations by HPLC and to genotype for two SVCT1 (rs4257763 and rs6596473) and two SVCT2 (rs6139591 and rs2681116) polymorphisms. Results: No diet-gene interactions were observed for the vitamin C transporter polymorphisms, however, the average (mean ± SE) serum ascorbic acid concentrations differed between rs4257763 genotypes (GG: 24.4 ± 1.3, GA: 26.8 ± 1.1, AA: 29.7 ± 1.4 μmol/l; p = 0.002). For this polymorphism, the correlation between dietary vitamin C and serum ascorbic acid was only significant in subjects with a G allele. The SVCT2 polymorphisms also appeared to modify the strength of the diet-serum correlation. Conclusions: Our findings demonstrate that genetic variation in SVCT1 can influence serum ascorbic acid concentrations and that SVCT1 and SVCT2 genotypes modify the strength of the correlation between dietary vitamin C and serum ascorbic acid.