Possibility of preventing colorectal carcinogenesis with probiotics.

Background/Aims: There have been no reports on the relationship between the analyses of the intestinal flora of colorectal cancer patients and colorectal carcinogenesis. In this study we investigated the differences between the intestinal flora of colorectal cancer patients and healthy subjects and assessed the possibility of using probiotics to prevent colorectal carcinogenesis. Methodology: The subjects were 10 colorectal cancer patients and 20 healthy persons. A stool specimen and peripheral blood specimen were collected from the patients and 10 of the healthy subjects to analyze their intestinal flora and measure natural killer (NK) cell activity and IL-1 β in their blood. Probiotics (Lactobacillus gasseri OLL2716: LG21) was then administered once daily to 10 of the healthy subjects for 12 weeks. Samples were collected after 4 weeks, 8 weeks, and 12 weeks of administration, and the same examinations were performed. Results: The Lactobacillus detection rate was significantly higher in the healthy group than in the colorectal cancer group, and the total Clostridium perfringens was higher in the colorectal cancer group. The stool pH of the colorectal cancer group indicated alkalosis, and the total amount of short-chain fatty acids in the stools tended to be lower than in the healthy group. After ingestion of the probiotic, the Lactobacillus detection rate increased, a decrease in the total amount of Clostridium perfringens was seen, fecal pH indicated acidosis, synthesis of fecal putrefaction products was inhibited, and an increase in the short-chain fatty acid isobutyric acid was observed. The blood IL-1 β and NK cell activity values were significantly higher from the 4th week onward than the values before ingestion of probiotics. Conclusions: A deterioration of the intestinal environment was observed in the colorectal cancer patients in comparison to the healthy controls, and the intestinal environment improved when probiotics was taken. These findings suggest the possibility of preventing colorectal carcinoma with probiotics.