Dear Dr. K: I’ve read several articles by you about the immune health benefits of probiotics. In a recent Wall Street Journal (WSJ) article I read that gut flora could lead to colon cancer. Can you tell me more?

Yes I can. You are actually touching on a subject of cutting-edge research. There have been three recent publishings (probably the fodder for the WSJ piece) on this subject: New England Journal of Medicine, Genome Research and Cell Host Microbe.

The bacterial species that seems to be the culprit is Fusobacterium nucleatum. This unwelcome gut bacteria is not considered part of the normal flora. It seems to create its mischief by producing a unique protein called FadA, which is a sticky protein called an adhesion antigen. This molecule “sticks” to colon cells and causes both inflammation and eventually cancerous changes in the cells.

Studies done in mice models demonstrate that blocking adherence of this protein, even without removing the Fusobacterium, protects the mouse colon from inflammation and cancer. Thus, human research is looking at ways to accomplish the same thing in people, and also ways to eradicate the bacteria.

This research shouldn’t come as too big a surprise in view of the discovery about 15 years ago that another bad gut bacteria called helicobacter pylori is the cause for most stomach ulcers (inflammation) and stomach cancer.