Racial and Aging Effects of Acute Antioxidant Supplementation

BACKGROUND: African Americans (AA) have a significantly higher risk of cardiovascular disease (CVD) compared to Caucasians (CA). This could be due to the elevated oxidative stress (OS) seen in AA. There are also significant sex differences in CVD, with post-menopausal females surpassing males in CVD risk factors, potentially due to the loss of estrogen, which has antioxidant properties. In addition, aging leads to elevated OS and vascular dysfunction. Acute antioxidant supplementation (AOX) has been shown to reduce free radicals and improve vascular function. METHODS: We investigated the effects of AOX on endothelial function, arterial stiffness, exercise blood flow, central and peripheral blood pressures and oxidative stress biomarkers in AA versus CA, and in males versus females, and if this relationship changes differently with aging. Applanation tonometry and ultrasonography were used to measure pressures, arterial stiffness values and blood flow during handgrip exercise. Endothelial function was assessed using strain gauge plethysmography and flow-mediated dilation, and oxidative stress biomarkers were assessed by measuring levels of superoxide dismutase, protein carbonyls and thiobarbituric acid reactive substances. RESULTS: In young adults, there are racial differences in resistance vessel response to reactive hyperemia following AOX, with no effect of race on macrovascular function (FMD%) following AOX. Older CA adults improved resistance vessel function with AOX whereas AA reduced resistance vessel response with AOX. FMD% improves following AOX in both CA and AA, with a greater improvement in AA. There was a significant effect of race, exercise and AOX on forearm vascular conductance (FVC) response with exercise in the older group. Young females displayed significantly higher FMD% but males improved FMD% with AOX. In older adults, although both sexes improved with AOX, females improved significantly more. Microvascular function was consistently higher in males compared to females. FMD% appears to be the most affected by sex and antioxidant supplementation, especially in older females. CONCLUSIONS: Our data indicate that AOX affects macrovascular function and microvascular function differently, and this is impacted by age, race and sex.