SCFAs are produced by the fermentation of dietary fiber by gut bacteria and have been shown to not only inhibit the activation of nuclear factor kappa B (NF-κB) and facilitate the differentiation of regulatory T cells (Tregs) but also to enhance the performance of immune checkpoint blockade therapies, particularly in the context of dietary fiber intake.20,21 These metabolites can modulate the expression of immune checkpoint molecules, including programmed cell death protein 1 (PD-1) and its ligand PD-L1, which are crucial targets in cancer immunotherapy.22 This evidence concerns the gene PDCD1 and cancer.