Alanine Amino Transferase Concentrations Are Linked to Folate Intakes and Methylenetetrahydrofolate Reductase Polymorphism in Obese Adolescent Girls

ABSTRACT Objective: The objective of this study was to investigate the consequences of low dietary folate intake and the impact of the 677 C→T methylenetetrahydrofolate reductase (MTHFR) common mutation on liver function in obese adolescents. Methods: Fifty‐seven obese girls (BMI = 36.1 ± 6.0 kg/m2) aged 14.1 ± 1.5 years were included before starting a weight reduction program. Dietary intakes for folate were assessed by means of an adapted food frequency questionnaire (n = 50). Liver enzymes, plasma lipids, glucose metabolism parameters, ferritin, homocysteine and erythrocyte folate content were measured in plasma or blood obtained under fasting conditions. The MTHFR 677 C→T polymorphism, which is associated with decreased enzyme activity, was determined using PCR. Body composition was assessed using dual x‐ray absorptiometry. Results: Twenty‐three subjects were heterozygote (CT) for the mutation and 5 were homozygote (TT). An increase in alanine amino transferase (ALT) and ALT/aspartate aminotransferase ratio was associated with the mutation (F = 4.46, P = 0.016 and F = 5.92, P = 0.0049, respectively). Alanine amino transferase was correlated negatively to folate intake (r = −0.32, P = 0.024) (n = 50) and positively to homocysteine concentrations (r = 0.30, P = 0.025). Body composition was similar among the 3 genotypic groups. Ferritin was also correlated to ALT concentrations of the entire group (P = 0.009). Conclusion: Our data suggest that folate intake and the MTHFR polymorphism represent a part of the link between antioxidant status and liver disease in obese adolescent girls.