Such SCFAs mainly include butyric acid, acetic acid and propionic acid, which all play roles in biological functions like anti-tumor and cancer prevention.99 In cell experiments, research found that physiological doses of acetic acid, propionic acid and butyric acid could inhibit the growth and proliferation of colorectal tumor cells, induce tumor cell differentiation and apoptosis, and play an anti-tumor role.79 Butyric acid plays a particularly important role in anti-tumor activity.100 Butyric acid induces the expression of β defensins through the muc2-dependent pathway. This evidence concerns the gene MUC2 and neoplasm.