α-Tocopherol supplementation reduces biomarkers of oxidative stress in children with Down syndrome: a randomized controlled trial

BACKGROUND: Down syndrome (DS) is the most common human chromosomal abnormality. It is characterized by mental retardation and several metabolic disturbances, including elevated oxidative stress, which may be causally linked. Treatment with dietary antioxidants has been suggested as a potential method to alleviate the oxidative damage and retardation of DS patients, but prior supplementation work has been equivocal. AIM: To evaluate the effects of supplementation with antioxidants alpha-tocopherol and alpha-lipoic acid (ALA) on oxidative stress biomarkers in DS children. METHODS: Ninety-three DS children aged 7-15 years from both sexes were randomly allocated to three groups: a-tocopherol (400 IU/day), ALA (100 mg/day) and placebo. The intervention period was 4 months. A healthy control group consisted 26 non-DS siblings. Serum thiobarbituric acid reactive substances (TBARS) and urinary 8-hydroxy-2'-deoxyguanosine (8OHdG) were used as biomarkers of oxidative stress. RESULTS: DS children had greater levels of baseline oxidative stress than their siblings. Moreover, males had greater levels of 8OHdG than females (P < 0.001) but there was no significant association between age and biomarkers of oxidative stress. Serum levels of TBARS did not change significantly over time, or relative to placebo. Although urinary 8OHdG concentrations decreased significantly in both a-tocopherol and ALA, groups compared with the baseline levels (P < 0.001), mean final levels of urinary 8OHdG concentrations differed significantly only between a-tocopherol and placebo groups (P < 0.01). CONCLUSIONS: alpha-Tocopherol supplementation of the diets of DS children may attenuate oxidative stress at the DNA level.