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 ( B. adolescentis , B. longum , and B. bifidum ) based on the identification of bacterial species that showed significant correlations with CRC-related bacteria including Fusobacterium nucleatum ( Fn ), Lachnoclostridium sp. m3 , Clostridium hathewayi ( Ch ), and Bacteroides clarus ( Bc ). We co-cultured Fn with each bifidobacterium or the combined formula and examined the growth of Fn by qPCR. The three individual bifidobacteria significantly inhibited the growth of Fn compared to the control treatment (24~65% inhibition; all p < 0.001). The combination of the three bifidobacteria showed a greater inhibitory effect on Fn growth (70% inhibition) than the individual bifidobacteria (all p < 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 ( Fn , m3 , Ch , and Bc ) were quantitated by qPCR before and after the intervention, and the combined CRC risk score (4Bac; Fn, m3 , Ch , and Bc ) was evaluated. Subjects with probiotics intervention showed significantly increased abundances of the bifidobacteria from week 2 to week 5 compared to baseline ( p < 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 ( Fn and m3 ) and the CRC risk score (4Bac) from week 2 to week 12 compared to baseline levels ( p < 0.05) in the intervention group but not in the control group. A novel probiotic formula containing B. adolescentis , B. longum , and B. bifidum was effective in inhibiting the growth of F. nucleatum in vitro and improving the gut microbial environment against CRC development.