Probiotics in the prevention of colorectal cancer

We review the most recent data generated by studies in animal models and clinical trials on the role of probiotics in preventing colorectal cancer and the mechanisms proposed. Reduction of colonic carcinogenesis has been attributed to controlling colorectal neoplastic progression via an increased proportion of bacteria with proinflammatory characteristics. Studies in humans have examined the effect of oral administration of yogurt supplemented with probiotics on intestinal microbiota associated with colorectal cancer. A significant decrease in these cells was reported in the probiotic treatment group but not in the milk control group, implying the potential of probiotics for eliminating microbiota associated with colorectal cancer. An intervention study undertaken in the pouches of patients with familial adenomatous polyposis showed decreased cell proliferation and increased detoxification capacity after treatment with probiotics and sulindac/inulin. This mechanism and others were demonstrated experimentally in animals using a rat colon cancer model to examine colorectal tumorigenesis and DNA damage. In the future, with growing understanding of the human microbiome, probiotics may serve as chemoprotective agents for the prevention of colorectal cancer. However, more clinical trials in humans are needed to assess their protective effect.