Investigating the Power of Bacteria
Bacteria play a central role in digestion and metabolism. AICR-funded research is looking into their potential role in inflammation and cancer.
Nine of every ten cells in our bodies are actually very tiny organisms called “microbes.” They play a central role in digestion and metabolism. The vast majority of microbes, such as bacteria, are found in the gastrointestinal tract. They also influence immune responses.
Certain microbes are known carcinogens, such as Helicobacter pylori, which causes stomach cancer and human papillomavirus, known to cause cervical cancer. But other microbes are essential to good health.
A Question of Balance
If the balance of bad microbes outweighs the number of good microbes, a situation known as dysbiosis occurs. Some studies suggest that in the gut, dysbiosis can increase risk for colorectal cancer. Liver and pancreatic cancers may also be triggered by dysbiosis.
A microbe imbalance can happen in the gut when you take antibiotic medications. Eating probiotics, live cultures of microbes found in some fermented foods, is believed to restore balance and healthy digestion. However, researchers still know little about the impact of probiotics (see box, right).
AICR grantee Christian Jobin, PhD, Professor of Infectious Diseases and Pathology at the University of Florida, is looking into the role of gut microbes’ dysbiosis in colorectal tumor formation and growth.
Previous studies showed that a common probiotic “cocktail” will prevent inflammation in mice if given before inflammation occurs. However, Dr. Jobin found that although probiotics drastically change microbial composition, they actually increase tumor production if given after the inflammation has occurred. Why? Dr. Jobin explains that a group of protective microbes called Clostridium decreased in the mice that were fed probiotic supplements. Clostridium typically produce a substance called butyrate that has anti-inflammatory and anti-cancer effects.
Dr. Jobin says research is needed and that people should be wary of probiotic supplements, which are not regulated. Instead, he suggests that eating a fiber-rich diet that encourages the production of butyrate, found in whole grains and other high-fiber foods, might be safer than taking probiotic supplements until more research on probiotics and cancer is done.
“We are just at the beginning of a new age in medicine,” Dr. Jobin says, “one in which we may be able to harness the power of bacteria.”