Glutathione S‐transferase gene polymorphisms and vitamin C

Abstract

Genetic polymorphisms of glutathione S‐transferases (GSTs) have been shown to affect fasting serum ascorbic acid (vitamin C) concentrations. The objective of this study was to determine whether three common polymorphisms in the GSTM1, GSTT1 and GSTP1 genes modify the serum ascorbic acid response to dietary vitamin C. Non‐smoking men and women (n= 1016) aged 20‐29 completed a 196‐item food frequency questionnaire that was used to estimate vitamin C intake, and provided a fasting blood sample for genotyping and determining serum ascorbic acid concentrations by HPLC. A significant diet‐gene interaction was observed for the GSTT1 polymorphism (p = 0.04). After adjusting for caloric intake, sex, ethnicity, season, c‐reactive protein and BMI, the Spearman correlation between dietary vitamin C and serum ascorbic acid was 0.36 (p<0.0001) for the GSTT1*0/*0 genotype and 0.14 (p=0.01) for the GSTT1*1/*1 + *1/*0 genotypes). Average serum ascorbic acid concentrations (mean ± SE) were higher among individuals with the GSTT1*1/*1 + *1/*0 than those with the GSTT1*0/*0 genotype (28.8 ± 1.1 versus 25.4 ± 1.5μmol/L) (p= 0.04, adjusted for caloric intake, sex, race, season, c‐reactive protein and BMI). No significant diet‐gene interactions were observed for GSTM1 (p=0.59) or GSTP1 (p=0.72). Our findings suggest that GSTT1 genotypes modify the serum ascorbic acid response to vitamin C intake.Grant Funding SourceAdvanced Foods & Materials Network