A system and method for reducing the likelihood of colorectal cancer in a human being includes the modification of an individual's gut microbes by employing a Clustered Regularly Interspaced Short Palindromic Repeats-CRISPR-associated system (CRISPR-Cas) or Clustered Regularly Interspaced Short Palindromic Repeats from Prevotella and Francisella 1 (CRISPR/Cpf1) system to modify only bacterial genes of bacteria that reside in the human gut that are non-homologous to those encompassed in the human genome, and in particular, to administer a therapeutically effective amount of a bacterial formulation comprising F. prausnitzii that has been modified to produce one of alliin or butyrate.