Racial differences in free radical scavenging enzyme activity in children.

Oxygen-derived free radicals play an important role in multiple pediatric neurologic diseases. Five intracellular free radical scavenging enzymes and three trace elements provide a significant portion of the body's defenses against free radical-mediated injury. Although the effects of age, sex, and ethnicity on the body's antioxidant defenses have been described, no study has examined whether racial differences exist. This pilot study sought to determine the effect of racial differences on the activity of five free radical scavenging enzymes and the concentrations of three associated trace elements in normal, healthy American children. The erythrocyte and plasma activities of five major free radical scavenging enzymes (glutathione peroxidase, glutathione reductase, glutathione-S-transferase, catalase, and superoxide dismutase) and plasma concentrations of three associated trace elements (selenium, copper, and zinc) were determined for 83 healthy American children, aged 1 to 18 years. One- and two-way interactions of race, age, and sex with each dependent variable were analyzed. African-Americans had higher erythrocyte glutathione peroxidase activity, erythrocyte superoxide dismutase activity, and selenium and copper concentrations than Caucasians. Racial inequalities do exist in free radical scavenging enzyme activity and trace element concentration in healthy children. African-American children had higher activity in the two most important free radical scavenging enzymes used by the brain compared to age- and sex-matched Caucasian children. Future clinical research in free radical-mediated pediatric neurologic diseases needs to consider race along with age and sex in both study design and data analysis.