Obese patients with concomitant CRC show specific gut microbiota profile characterized by a reduction in butyrate-producing bacteria and an overabundance of opportunistic pathogens, which, in turn, may be responsible, at least partially, for the higher levels of proinflammatory cytokine IL-1β, the deleterious bacterial metabolite trimethylamine N-oxide (TMAO) and gut permeability found in these patients [153]. This evidence concerns the gene IL1B and colorectal carcinoma.