At the enzyme level, sulfur-producing enzymes were associated with CRC (including EC 4.4.1.2 homocysteine desulfhydrase (SMD = 0.52, q < 0.001) and EC 1.8.1.8 protein disulfide reductase (SMD = 0.41, q < 0.001)), consistent with previous work32 (Extended Data Fig. 7a and Supplementary Table 6). Here, CTH is linked to colorectal carcinoma.