A high-fat, low-carbohydrate diet, known as a ketogenic diet, can aid weight loss by forcing the body to burn fat instead of sugar. Recent studies have explored its effects on health, particularly cancer. While some research indicates that ketogenic diets may protect against colon cancer, a new MIT study suggests they might increase cancer risk in the small intestine.
Omer Yilmaz, director of the MIT Stem Cell Initiative, stated, "Ketogenic diets have distinct effects on different tissues even within the gastrointestinal tract. We must be cautious in generalizing the effects of these diets, as what may be beneficial for one tissue could be detrimental for another." This study appears in today's issue of Nature.
Originally developed in the 1920s to treat epilepsy, ketogenic diets have been adapted over recent decades as a strategy for weight loss or longevity. This diet consists of a high percentage of fat, low carbohydrates, and normal or reduced protein. It compels the body to burn fatty acids for energy instead of carbohydrates, producing ketone bodies as byproducts of fat metabolism.
A 2022 Nature study suggested that ketogenic diets protect against colon cancer, with BHB, the most abundant ketone body, being a key factor. In the new study, the MIT team examined whether ketogenic diets could have a similar protective effect in the small intestine. They fed genetically predisposed mice a ketogenic diet, a control diet, or a high fat/high calorie diet, finding that those on the ketogenic diet were more likely to develop small intestinal tumors.
These mice did not become obese; however, they developed tumors at rates similar to or higher than those on a high fat/high calorie diet. Further studies revealed that ketone bodies did not contribute to tumor development. Instead, tumor growth was driven by how intestinal cells metabolize dietary fat through a pathway known as fatty acid oxidation, activating a family of proteins called PPARs that signal stem cells to proliferate more rapidly, increasing the risk of cancerous transformation.
Surprisingly, the same ketogenic diet that promoted tumors in the small intestine suppressed tumor development in the colon, echoing findings from the earlier Nature study. Yilmaz noted that tumor acceleration was driven entirely by how stem cells process dietary fat, not by ketone bodies.
The research team aims to further investigate the contrasting effects of ketogenic diets in the colon and small intestine. Understanding these tissue-specific effects is crucial as ketogenic diets gain popularity. The implications of this research are significant, indicating that commercial ketone supplements would not replicate the risks or benefits observed in the study.
Blogger's Review: The differential effects of ketogenic diets on the small intestine versus the colon are a crucial reminder of the complexity of dietary impacts on health. This study underscores the need for caution when adopting dietary strategies, particularly concerning cancer risks, and highlights potential avenues for future research in cancer prevention and treatment.