The result showed that glutamine (OR 0.985, 95% CI 0.972–0.997; P-value = 0.019) and apolipoprotein A-I (OR 0.990, 95% CI 0.981–0.999; P-value = 0.036) were negatively associated with depression, indicating a protective effect on depression. This evidence concerns the gene APOA1 and major depressive disorder.