A Probiotic Formula for Modulation of Colorectal Cancer Risk via Reducing CRC-Associated Bacteria.

Gut microbiota dysbiosis with increased pathogenic bacteria and decreased beneficial bacteria is associated with colorectal cancer (CRC) development. This study examined the effect of a newly developed probiotic formula in modulating CRC-related bacteria. We developed a probiotic formula containing three bifidobacteria (, , and ) based on the identification of bacterial species that showed significant correlations with CRC-related bacteria including (), , (), and (). We co-cultured with each bifidobacterium or the combined formula and examined the growth of by qPCR. The three individual bifidobacteria significantly inhibited the growth of compared to the control treatment (24~65% inhibition; all < 0.001). The combination of the three bifidobacteria showed a greater inhibitory effect on growth (70% inhibition) than the individual bifidobacteria (all < 0.05). We further examined the effect of the probiotic formula in a pilot study of 72 subjects (40 on probiotics; 32 with no intervention) for 4 weeks and followed them up for 12 weeks. The relative fecal abundances of the bifidobacteria in the formula and the CRC-related markers (, , , and ) were quantitated by qPCR before and after the intervention, and the combined CRC risk score (4Bac; , , and ) was evaluated. Subjects with probiotics intervention showed significantly increased abundances of the bifidobacteria from week 2 to week 5 compared to baseline ( < 0.05), and the abundances dropped to baseline levels after the cessation of the intervention. There were significant decreases in the levels of CRC-related markers ( and ) and the CRC risk score (4Bac) from week 2 to week 12 compared to baseline levels ( < 0.05) in the intervention group but not in the control group. A novel probiotic formula containing , , and was effective in inhibiting the growth of in vitro and improving the gut microbial environment against CRC development.