Thus, our findings showed that microbiota-derived QA is used as an alternative source of replenishing the intracellular NAD<sup>+</sup> pool induced by SIRT3 deficiency to regulate IEC and T cell function, which has implications for targeting IECs as an approach to the treatment of immune-associated diseases, including colorectal cancer and colitis. Here, SIRT3 is linked to colorectal cancer.