Vitamin C Transporter Gene Polymorphisms, Dietary Vitamin C and Serum Ascorbic Acid

Abstract

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.

Vitamin C transporter gene (SLC23A1 and SLC23A2) polymorphisms, plasma vitamin C levels, and gastric cancer risk in the EPIC cohort

“…SLC23A2 rs6116569 is a tagSNP with unknown function, and in our data, it showed no detectable effect on plasma vitamin C levels. Our results showing associations between the SNP markers rs11950646, rs6053005, and rs6133175 and plasma vitamin C concentration have not been directly observed in other study populations; however, previous studies have evaluated SLC23A1 and SLC23A2 SNPs and blood vitamin C concentrations in large sample sizes (Cahill and El-Sohemy 2009;Timpson et al 2010). …”

“…SLC23A1 rs4257763 is not in HapMap, but has been reported to be in partial LD with rs6596473 (for which we observed no associations) (Cahill and El-Sohemy 2009). …”

“…Cahill and El-Sohemy reported an association between SLC23A1 rs4257763 and mean serum vitamin C levels from 12-h fasting blood in a cross-sectional study of 1,277 volunteers (39 % Caucasian, and 29 % East Asian and the remainder of mixed race/ethnicity) (Cahill and El-Sohemy 2009). SLC23A1 rs4257763 is not in HapMap, but has been reported to be in partial LD with rs6596473 (for which we observed no associations) (Cahill and El-Sohemy 2009).…”

Dietary Antioxidant and Oxidative Stress: Interaction between Vitamins and Genetics

“…Accordingly, several variations to the status of vitamin C have been identified in several genes. A study with healthy young individuals of different ethnicities identified an association between variations in the SLC23A1 gene and circulating concentrations of ascorbic acid [24]. These findings were replicated later in a population of more than 15.000 individuals of European descent [25].…”

Haptoglobin genotype modifies the association between dietary vitamin C and serum ascorbic acid deficiency

“…These inconsistencies may be due to individual genetic variation in the serum ascorbic acid response to dietary vitamin C. In addition to Hp, other genes contain common polymorphisms that were recently shown to be potential determinants of serum ascorbic acid, including the genes that code for glutathione S-transferases (50, 51) and vitamin C transporters (52,53). An additional reason for studying these diet-gene interactions is that inconsistencies between genetic association studies, such as haptoglobin polymorphism and risk of cardiovascular outcomes in nondiabetic individuals (23), may be due, in part, to the gene-disease association being present only when a dietary factor such as vitamin C or fruit and vegetable intake is inadequate.…”