Randomized Study to Assess Colonic Microbiota Changes in Response to Energy Drink Consumption

Colorectal cancer (CRC) is the 2nd leading cause of cancer deaths in the US. The bulk of new diagnoses typically occurs after the age of 50 for those without personal or family histories of this disease. However, rates of colorectal cancer have been slowly increasing in incidence in those younger than 50, recently prompting the U.S. Preventative Services Task Force to recommend reducing the age of routine screening to 45. The reason for the rising incidence of CRC in younger individuals (eoCRC) is unclear but with many speculative causes postulated. One of the most frequently cited possible causes relates to changes in the young adult colonic microbiome which either removes a protective mechanism or promotes a carcinogenic process. The latter is the hypothesis being persued.

Certain commensal bacteria produce hydrogen sulfide (H2S) during fermentation of sulfate containing compounds such as sulfur amino acids. For example, Fusobacterium nucleatum produces H2S from metabolizing methionine and cysteine. Atopobium parvulum is another potent H2S producer and is implicated in halitosis. Importantly, H2S has the capacity to induce inflammation and possesses genotoxic and potentially pro-tumorigenic properties, particularly when consistently present over a prolonged period of time. While Fusobacterium and Atopobium are minor members of the normal gut microbiota, recent studies showed that they are overrepresented in CRC patients. The invvestigators published that the relative abundance of A. parvulum was positively correlated with the severity of pediatric inflammatory bowel disease (IBD). Moreover, the investigators observed that Il10-/- mice colonized by A. parvulum developed severe colitis, which was attenuated by a chow diet containing the H2S scavenger bismuth. Together, this data suggests that bacteria-derived H2S may contribute to intestinal pathologies including the creation of a pro-inflammatory and pro-carcinogenic environment, which could be modulated by availability of dietary sulfur contents.

One major energy source for H2S producing gut microbiota is taurine, an essential amino acid found in very high levels/concentrations in energy drinks. The typical American diet provides between 123 and 178 mg of taurine daily. However, consumption of one 8-oz energy drink can increase the average taurine intake 6 to 16 times that our regular diet. The hypothesis being persued is that energy-drinks, through their high taurine content, favors expansion of already present bacteria producing H2S, thereby representing an association with a carcinogenic risk-factor that might help explain the rise in eoCRC cases and developing future interventions to mitigate this risk.