Study: High-Fat Diets May Raise Cancer Risk

Mice on high-fat diets developed more tumor-causing intestinal stem cells.

Fat is like a contestant on Project Runway: One day, it’s in, and the next day, it’s out.

A new study from Dana-Farber Cancer Institute and Boston Children’s Cancer and Blood Disorders Center, however, gives low-fat advocates new evidence. Researchers found that following a high-fat diet may up an individual’s risk of developing colon cancer.

The team, led by researcher Semir Beyaz, found that, compared to mice on lower-fat diets, mice eating lots of fat gained significant body weight and produced more intestinal stem cells, as well as cells that behave like stem cells—in other words, rapidly growing and changing. Intestinal stem cells are linked to mutations that can lead to colon cancer (as is obesity), and intestinal tumor formation.

Beyaz and his colleagues fed mice a 60 percent-fat diet for almost a year. These mice produced large numbers of intestinal stem cells that could function independently, which implies the possibility for unchecked growth and division characteristic of cancer. The subjects’ progenitor cells, which mimic stem cells’ behavior, had similar capabilities.

“The epidemiological link between a high-fat diet and colorectal cancer has been reported for many years, but the underlying mechanisms were not known,” Beyaz said in a statement. “Our study for the first time showed the precise mechanisms of how a high-fat diet regulates intestinal stem cell function and how this regulation contributes to tumor formation.”

It’s too soon to throw out all your cheese and butter, though. First, the study was performed on mice, so the results may not be totally indicative of humans. Second, getting 60 percent of your calories from fat, as the mice did in the study, isn’t likely—the average human’s fat consumption makes up between 20 and 40 percent of his diet. Third, and perhaps most importantly, the professional opinion on fat is a constant yo-yo.

There are experts who firmly believe the low-fat craze of decades gone by was wholly misguided, and that eating fat does not actually make us fat. Some still say low-fat, at least for some foods, is the way to go. There are studies that say low-fat diets won’t help you lose weight. There are others that say limiting fat helps prevent heart disease. In short, researchers’ opinions and recommendations change frequently.

While the study adds depth to the idea that weight and diet may contribute to cancer formation, more research is necessary before you take its findings with anything more than a grain of salt—or, more aptly, a pat of butter.