Cocoa Polyphenols Modulate the Fecal Microbiome in a Mouse Model of Colitis, Independent of Basal Diet and Colon Inflammation

Chronic inflammation increases the risk of developing multiple chronic diseases, including cancer. The risk of developing colorectal cancer (CRC) specifically is increased in individuals who suffer from colitis, a characteristic of Inflammatory Bowel Disease (IBD). Diet is another risk factor for developing CRC, particularly an inflammation-promoting Western-type diet. Thus, supplementing a Western diet with functional foods containing anti-inflammatory polyphenols is a potential approach to decreasing CRC risk by reducing gut inflammation and altering gut microbiome profile. This study aimed to determine the effects of cocoa polyphenol (CP) supplementation on inflammation status and microbiome profile before, during, and after colitis when fed in the context of a healthy diet or a Western diet in a mouse model of colitis. We hypothesized that mice fed a Western diet would experience greater colon inflammation than mice consuming a healthy rodent diet and that this effect would be attenuated when a Western diet is supplemented with CPs. We further hypothesized that mice fed the cocoa-supplemented diet would have a differentiated microbiome profile than those eating a Western diet alone. A 2x2 factorial design was used to examine the effect of basal diet, in the form of either the AIN93G healthy rodent diet and the total Western diet (TWD), and the effect of CP consumption. The CP-supplemented diets contained 2.6% (w/w) CocoaViaTM Cardio Health Powder, a polyphenol-enriched supplement. The AOM/DSS model of colitis was used to induce inflammation. Supplementation with CP did not decrease colon inflammation when measured by disease activity index or histopathology but did alter fecal microbiome composition before disease induction and continued to affect the abundance of several rare taxa during chemically induced colitis and recovery. These results indicate that the ability of CPs to alter inflammatory pathways may not be strong enough in vivo to decrease clinical inflammation. However, consumption of CPs does alter microbiome profile and may affect other immune pathways in the colon that are related to cancer development. In conclusion, our results indicate that basal diet is the driving factor promoting inflammation, mucosal damage, and colitis symptoms in this model.