Is there a link between obesity and cancer?

If you’re overweight, your doctor may warn you about an increased risk for certain health conditions, including diabetes, heart disease and stroke. Researchers have long suspected a link to certain cancers as well and now say they’ve found a connection to liver, pancreatic, colorectal and esophageal cancers that start in your gut.

According to a recent study published in the journal Nature, researchers in Tokyo found that obesity changes the microbes and bacteria in the digestive system which damage DNA, causing cancerous tumors to develop.

Experimenting with mice, scientists found that obesity leads to the production of microbes and, in turn, the cancer-causing bacteria in the intestinal tract. The bacteria secrete deoxycholic acid (DCA), a bile acid that damages the DNA leading to the growth of tumors.

According to the research, treating the affected mice with antibiotics to kill the microbes reduced the risk of liver cancers.

“It is clear that the increased levels of DCA produced by gut bacteria play key roles in the promotion of obesity-related liver cancer,” the authors wrote in the study.

Dr. Ajay Maker, director of surgical oncology at Advocate Illinois Masonic Medical Center in Chicago, says he is very interested in the study results.

Dr. Maker is careful to note that obesity itself isn’t the actual “cause” of cancer in this article. In this study, obesity seems to create a situation in which the liver is more sensitive to cancer-inducing signals, he says.

“We know that obesity is associated with certain disease processes, including cancer, but the mechanisms are not well understood,” Dr. Maker says. “What’s very interesting is this study has found that obesity affects the bacteria in our gut and that one of the bacterial byproducts sensitizes liver cells to a cancer-promoting signal. This opens up many doors for further research into the affects of obesity on our bodies, including cancer, and on ways to possibly counteract them.”

Dr. Maker says the study also serves as a good reminder that people need to do all they can to maintain a healthy weight given all the health threats posed by being overweight or obese.