A reason to eat carbs

A high-fat, low-carbohydrate diet can help some people lose weight, and some research has shown that it may protect against colon cancer. But a new study suggests that such a ketogenic diet may also increase the risk of cancer in the small intestine.

This type of diet forces the body to burn fatty acids instead of carbohydrates for fuel, producing by-products called ketone bodies. One of these, BHB, was thought to be responsible for the protective effect observed against colon cancer.

Omer Yilmaz, director of the MIT Stem Cell Initiative, worked with colleagues including MIT postdocs Jessica Shay and Fangtao Chi to investigate whether the effects were similar in the small intestine. But instead, they found that mice on a ketogenic diet were more likely to develop tumors in that part of the gastrointestinal system than those on a control diet were.

Additional studies revealed that this tumor growth was driven by the way intestinal cells burn dietary fat for …