Uric acid and serum antioxidant capacity: a reaction to atherosclerosis?

Background: the evidence of a potential beneficial role of antioxidants in preventing atherosclerotic disease is not entirely consistent. Objective: t o assess the longitudinal association of serum total antioxidant capacity a nd serum antioxidants with the presence of subclinical carotid atherosclero sis. Methods: Prospective case-control study nested within an historical co hort. Cases were 150 individuals with elevated carotid intimal-medial thick ness measured by B-mode ultrasound at the first two examinations of the Ath erosclerosis Risk in Communities Study (1987-92). Controls were 150 age-gen der-matched individuals with low carotid intimal-medial thickness. Serum an tioxidant vitamins, uric acid, and serum total antioxidant capacity were me asured in frozen serum samples collected from the same individuals in 1974 (13-15 years prior to the determination of case-control status). Results: C ompared to controls, atherosclerosis cases had significantly higher levels of serum total antioxidant capacity in 1974 than controls. This difference was almost entirely explained by increased serum concentration of uric acid in cases. In contrast with cross-sectional results, uric acid serum concen tration in 1974, was significantly higher in cases than in controls, even a fter adjusting for the main cardiovascular risk factors. Cases had signific antly lower levels of cc-carotene in the 1974 sera than controls, but no ot her differences in serum antioxidant vitamin concentrations were observed. Conclusions: The higher serum uric acid concentration seemed associated wit h elevated total serum antioxidant capacity among individuals with atherosc lerosis. This finding is consistent with experimental evidence suggesting t hat hyperuricemia may be a compensatory mechanism to counteract oxidative d amage related to atherosclerosis and aging in humans. (C) 2000 Elsevier Sci ence Ireland Ltd. All rights reserved.