The causal effect of serum amino acids on the risk of prostate cancer: a two-sample mendelian randomization study

Prostate cancer (PCa) is the second most common malignancy affecting men globally. Recent advances in metabolomics have highlighted significant alterations in specific amino acid (AA) metabolism linked to PCa, indicating their potential utility in diagnosis and therapy. However, no direct causal association between serum AA levels and PCa risk has been established. A total of 35 patients with PCa and 30 individuals with benign prostatic hyperplasia (BPH) were recruited for this study. Targeted metabolomic analysis was performed using ultra-high-performance liquid chromatography-tandem mass spectrometry on serum samples. Two-sample Mendelian randomization (MR) was applied to explore potential causal links between serum AA levels and PCa risk, including mediator effects using dual-phase MR and assessing reverse causality through reverse MR. Results Targeted metabolomic profiling identified six amino acids-glutamate (Glu), Ser, histidine (His), arginine (Arg), aspartic acid (Asp), and glycine (Gly)-that showed significant area under the ROC curve in differentiating between BPH and PCa cases. Notably, Glu demonstrated an inverse association with PCa risk, distinct from the other AAs identified. However, definitive evidence supporting a causal relationship between low Glu levels and increased PCa risk was not observed. Our results suggest a protective role of Glu against PCa development, which may have implications for disease prognosis. Increasing dietary Glu intake may present a potential preventive or therapeutic approach for PCa.