Systemic uric acid administration increases serum antioxidant capacity in healthy volunteers

Oxidative stress plays an important role in the development of atherosclero sis and contributes to tissue damage that occurs as a consequence, particul arly in myocardial infarction and acute stroke. Antioxidant propel-ties of uric acid have long been recognized and, as a result of its comparatively h igh serum concentrations, it is the most abundant scavenger of free radical s in humans. Elevation of serum uric acid concentration occurs as a physiol ogic response to increased oxidative stress-for example. during acute exerc ise-thus providing a counter-regulatory increase in antioxidant defenses. I n view of its antioxidant properties, uric acid may have potentially import ant and beneficial effects within the cardiovascular system. We wished to i nvestigate whether administration of uric acid was feasible and if it could have an impact on antioxidant function in vivo. We have, therefore, perfor med a randomized, placebo-controlled double-blind study of the effects of s ystemic administration of uric acid. 1,000 mg, in healthy volunteers, compa red with vitamin C, 1,000 mg. We observed a significant increase in serum f ree-radical scavenging capacity from baseline during uric acid and vitamin C infusion, using two methodologically distinct antioxidant assays. The eff ect of uric acid was substantially greater than that of vitamin C.