Measurement of metabolites by GC-MS/MS
Serum samples for metabolite analysis were obtained from peripheral blood collected at the Seoul National University Health Care Center at the baseline, and at 3 and 6 months. The metabolites were analyzed using GC-MS/MS (Shimadzu GCMS-TQ8040) with multiple reaction monitoring ions at the Pesticide Chemistry and Toxicology laboratory of the Department of Agricultural Biotechnology of Seoul National University. The analytical conditions for serum metabolite analysis using GC-MS/MS were previously described in a study [