Une nouvelle étude: ce régime qui protège le côlon contre le cancer peut augmenter le risque de tumeurs ailleurs

A new study has revealed that a diet once believed to protect the colon from cancer could instead increase the risk of tumors in the small intestine. The research, conducted by scientists at the Massachusetts Institute of Technology (MIT) and published in the scientific journal Nature, challenges long-held assumptions about the effects of the ketogenic diet, a high-fat, low-carbohydrate eating plan popularized for weight loss and disease management. The study focused on mice with a genetic predisposition to colorectal cancer. Researchers divided the animals into three groups: one fed a ketogenic diet, another given standard chow, and a third consuming a high-fat, calorie-rich diet typically associated with obesity. Surprisingly, mice on the ketogenic diet developed tumors in their small intestines as frequently, or even more often, than those on the high-fat diet, despite showing no signs of weight gain. This finding contradicts previous studies suggesting that the same diet protects against colon cancer. Omer Yilmaz, director of the Initiative for Original Cells at MIT, led the research team. He explained that while the ketogenic diet was initially developed as a treatment for epilepsy, its popularity for weight loss has grown significantly over the past decade. The diet works by shifting the body’s primary energy source from carbohydrates to fats, producing ketone bodies that can fuel brain activity. These ketones have been linked to potential protective effects in the colon, as demonstrated in earlier studies from 2022. However, this latest research shows that the same dietary approach may have harmful consequences elsewhere in the digestive system. In laboratory settings, the team observed that the metabolic changes induced by the ketogenic diet triggered rapid cell proliferation in the small intestine. The process involves the activation of specific proteins that drive the replication of stem cells, which are crucial for tissue repair. While increased stem cell activity might aid recovery, it also raises the likelihood of mutations leading to malignancy. The researchers noted that ketone bodies themselves did not appear to directly cause tumor growth. Instead, they acted as metabolic signals influencing how intestinal cells process fat. When these cells metabolize large amounts of dietary fat, they activate pathways that promote uncontrolled division. The study found that this effect was independent of the presence of ketone bodies, indicating that the key factor was the overall metabolic shift toward fat utilization. This discovery highlights the complexity of dietary interventions and their impact on different parts of the body. The findings underscore the need for caution in applying broad conclusions about the health benefits of the ketogenic diet. Scientists emphasize that individual responses to such diets can vary widely depending on factors like genetics, gut microbiome composition, and existing health conditions. As the research community continues to explore the implications of these results, healthcare professionals and nutritionists will likely reassess recommendations for patients considering the ketogenic diet. The study serves as a reminder that while certain dietary strategies may offer benefits in one context, their effects can be entirely different, and potentially counterproductive, in others. For now, the focus remains on understanding the mechanisms behind these contrasting outcomes and determining whether targeted approaches could yield safer, more effective therapeutic options.