Method: Instrumental variables for glutamine (N=114,750), citrulline (N=7,773), testosterone (N=425,097), lactate (N=114,802), and MG (N=355,142) and LOMG (N=34,930) were obtained from publicly available summary data of genome-wide association studies. The primary analysis method was inverse variance weighting, with MR-Egger regression and weighted median methods used to assess the robustness of causal effects. Sensitivity analyses were conducted to examine horizontal pleiotropy and the stability of the results. For significant findings, Bayesian colocalization analysis was performed to evaluate whether there are shared causal variants.