Gut bacteria (green) in a section of colon. Our changing diet, hygiene practices and medical therapies can alter the microbes that live on and inside us—in good and bad ways.
Taking some antibiotics, which reduces the diversity of bacteria in the gut, may slightly increase the risk of developing colon cancer, a new study suggests.
Low diversity of gut bacteria has been linked to higher risk of colorectal cancer. To examine whether there's any link between taking antibiotics and the risk of colorectal cancer, researchers looked at the medical records of more than 22,000 colorectal cancer patients in the United Kingdom, and followed them for an average of six years.
The researchers excluded the patients who had a family history of colorectal cancer or inflammatory bowel disease to limit the factors that could affect the patients' cancer risk.
The researchers compared the amount of antibiotics the patients had taken at least six months before being diagnosed with cancer, to the amount of antibiotics taken by a group of about 86,000 healthy people.
After controlling for known risk factors for colorectal cancer — including obesity, diabetes, smoking and alcohol consumption — the results showed people who had taken antibiotics, including penicillins, quinolones and metronidazole, were 8 to 11 percent more likely to develop colorectal cancer.
For the rest of the story: http://www.livescience.com/46076-antibiotics-colon-cancer-risk.html