Skip to content

Bacteria and Colorectal Cancer

Some recent studies have explored the link between bacteria in the gut and colorectal cancer. The beneficial Prevotellaceae bacteria (mentioned in the Nov. 5 study below) have been discussed elsewhere as liking whole grain foods. So go feed your gut with some nice whole grain bread or cereal. And some fruits and veggies while you're at it. As mom used to say: "You are what you eat."

A study published December 6, 2013 found that decreased diversity of the gut microbiome and the presence of certain types of bacteria were associated with colorectal cancer in humans: Decreased Diversity of Bacteria Microbiome in Gut Associated Colorectal Cancer

From the November 5, 2013 Science Daily: Microbes in the Gut Help Determine Risk of Tumors

Transferring the gut microbes from a mouse with colon tumors to germ-free mice makes those mice prone to getting tumors as well, according to the results of a study published in mBio®, the online open-access journal of the American Society for Microbiology. The work has implications for human health because it indicates the risk of colorectal cancer may well have a microbial component.

Scientists have known for years that inflammation plays a role in the development of colorectal cancer, but this new information indicates that interactions between inflammation and subsequent changes in the gut microbiota create the conditions that result in colon tumors.

Known risk factors for developing colorectal cancer include consuming a diet rich in red meat, alcohol consumption, and chronic inflammation in the gastrointestinal tract (patients with inflammatory bowel diseases, such as ulcerative colitis, are at a greater risk of developing colorectal cancer, for instance).

The results were stark: mice given the microbiota of the tumor-bearing mice had more than two times as many colon tumors as the mice given a healthy microbiota. What's more, normal mice that were given antibiotics before and after inoculation had significantly fewer tumors than the mice that got no antibiotics, and tumors that were present in these antibiotic-treated mice were significantly smaller than tumors in untreated mice. This suggests that specific populations of microorganisms were essential for the formation of tumors...

Looking at the microorganisms, they found that tumor-bearing mice harbored greater numbers of bacteria within the Bacteroides, Odoribacter, and Akkermansia genera, and decreased numbers of bacteria affiliated with members of the Prevotellaceae and Porphyromonadaceae families. Three weeks after they were inoculated with the communities from the tumor-bearing mice, the germ-free mice had a gut microbiome that was very similar to the tumor-bearing mice, and they had a greater abundance of the same bacterial groups associated with tumor-formation.