Higher circulating levels of uric acid are prospectively associated with better muscle function in older persons

Background: Previous studies have shown that oxidative protein damage is independently associated with low grip strength and that dietary intake and circulating levels of antioxidant vitamins are positive predictors of muscle strength among older persons. Since uric acid (UA), has strong antioxidant properties, we tested the hypothesis that UA levels is cross-sectionaly associated with muscle strength and protective against the decline of strength over the aging process. Subjects and methods: 789 InCHIANTI Study participants underwent baseline serum UA, handgrip and knee extension torque measurements. Of these, 497 participants (226 men and 271 women, mean age 76.0 ± 5.4 years) also had follow-up strength measures. Lifestyle, comorbidities, nutritional profile, inflammatory markers and other laboratory measures were considered as potential confounders. Results: Follow-up strength measures significantly increased across baseline UA tertiles. After adjusting for potential confounders and analogous baseline strength measures, higher baseline UA levels still remained significantly associated with higher follow-up strength measures. Conclusions: Our findings suggest that higher levels of UA might represent a protective reaction aimed at counteracting the excessive production of free radicals that cause muscle protein damage and eventually contribute to the decline of muscle mass and strength.