Gut microbes provide link between carbs and colon cancer

the Oncology Nurse Advisor take:

Physicians have long suspected a link between carbohydrate intake and colon cancer development, and a recent study may have illuminated the sought-after link. Researchers associated with the University of Toronto treated mice, engineered to be colon cancer susceptible, with antibiotics in order to eliminate intestinal bacteria. By eliminating bacteria, the antibiotics slowed malignant polyp growth in the lining of the colon and small intestines. The investigators also noted that a low starch, low sugar diet further reduced polyp growth in the mice.

When the investigators examined gene mutations, two mutations common between mice and men were discovered. One of the two mutations affects the ability of cells to fix errors that occur during DNA replication, which can cause rapid cell division in the colon lining and lead to tumor growth. It appears that carbohydrates hasten the process, possibly because as microbes consume carbohydrates, the germs produce a chemical that prompt colon cells lacking the ability to repair DNA mismatches into tumor production. A comparison of mice on regular diets and mice eating butyrate-enriched food showed that the latter group had increased tumor polyps, lending evidence to the idea that a bacterially produced chemical serves as the conduit between carbohydrate intake and increased tumor development.

This research was published in the July 17th edition of Cell.