In glioma patients, TGF‐β has been shown to be upregulated and to take part importantly in glioma initiation and proliferation.38 Other mechanisms that could explain how alterations of the microbiota can affect the brain involve activation of the vagus nerve,39 neuroimmune pathways,40 microbial metabolites,41 and microbial‐derived neurotransmitters.42 For example, microbiota‐derived short‐chain fatty acids control microglia maturation and function.41 Here, TGFB1 is linked to glioma.