The microorganisms in the human gastrointestinal tract have a profound influence on the transformation of food into metabolites which can impact human health.
Gallic acid (GA) and
pyrogallol (PG) are bioactive compounds displaying diverse
biological properties, including carcinogenic inhibiting activities. However, its concentration in fruits and vegetables is generally low. These metabolites can be also generated as final products of
tannin metabolism by microbes endowed with
tannase, which opens up the possibility of their anti-
cancer potential being increased. Patients with
colorectal cancer (CRC) display an imbalanced gut microbiota respect to healthy population. The recent use of next generation sequencing technologies has greatly improved knowledge of the identity of bacterial species that colonize non-tumorous and tumorous tissues of CRC patients. This information provides a unique opportunity to shed light on the role played by gut microorganisms in the different stages of this disease. We here review the recently published gut microbiome associated to CRC patients and highlight
tannase as an underlying gene function of bacterial species that selectively colonize tumorous tissues, but not adjacent non-malignant tissues. Given the anti-carcinogenic roles of GA and PG produced by gut
tannin-degrading bacteria, we provide an overview of the possible consequences of this intriguing coincidence for CRC development.