As a noteworthy factor whose activity seen to correlate with depression in the cerebral cortex, xanthine oxidase was also inhibited by Lactobacillus paracasei CCFM1229 and Lactobacillus rhamnosus CCFM1228, which also became an essential link between Lactobacillus intervention in depression [89] Expectedly, there also existed researches attributing the protective effect of Lactobacillus to its product such as ergothioneine produced by Lactobacillus reuteri. The gene discussed is XDH; the disease is major depressive disorder.