We found that l‐arginine, an essential amino acid, was depleted in male mice, and that l‐arginine could significantly inhibit CRC cell growth, which was in line with the previous reports that l‐arginine are necessary for cell growth and differentiation‚ and it can reduce crypt cell hyper proliferation in CRC patients by increasing the NO concentration and decreasing ornithine decarboxylase (ODC) activity.[56, 57, 58] More importantly, we found that the elevated level of LPC was positively correlated with A. muciniphila in male mice, both of which promoted CRC development in male mice. This evidence concerns the gene ODC1 and colorectal carcinoma.