Laboratory measurements
DAAO and three antioxidants in peripheral blood were measured using the commercially available kits at baseline and endpoint.DAAO protein levels in serum were assayed with the kit according to the manufacturer's recommended protocol (Cloud‐Clone Corp, Houston, TX, USA). The detailed method has been described elsewhere.GSH levels in plasma were measured using the kit according to the manufacturer's recommended protocol (Cayman, Ann Arbor, MI, USA). The detailed method has been described elsewhere.SOD levels in plasma were analyzed using the kit according to the manufacturer's recommended protocol (Merck, Kenilworth, NJ, USA). The detailed method has been described elsewhere.CAT in plasma was measured using the kit according to the manufacturer's recommended protocol (Cayman, Ann Arbor, MI, USA). The detailed method has been described elsewhere.All of the aforementioned analyses were repeated twice.