A ketogenic diet (KD) is often promoted for lowering blood insulin and shifting metabolism toward ketone bodies. Yet how this high-fat, low-carbohydrate regimen affects cancer risk inside the gut has remained unclear—especially in people with inherited vulnerabilities. In a new study, researchers used mouse models that spontaneously develop intestinal adenomas to test whether KDs accelerate tumor growth and, crucially, whether any effect depends on ketone metabolites themselves or on other lipid-driven metabolic pathways.
The team built a multi-layered experimental framework combining dietary intervention, genetic edits in the ketogenic pathway, and targeted changes in lipid utilization. Their goal was to separate systemic ketogenesis from the local metabolic environment of the intestinal epithelium, an essential distinction because the gut rapidly processes dietary fats and nutrients.
They report that the KD consistently worsened outcomes: tumor burden increased and survival shortened. Importantly, this tumor acceleration occurred independently of circulating ketone metabolites. In other words, lowering insulin and boosting ketone production were not sufficient to explain the increased adenoma formation.
To probe causality, the investigators genetically manipulated 3-hydroxy-3-methylglutaryl-coenzyme A synthase 2 (HMGCS2), a key ketogenic enzyme. Whether they reduced or enhanced HMGCS2 activity, altering production of local and systemic ketone metabolites, the resulting changes did not translate into meaningful differences in intestinal tumorigenesis. The same held when they disrupted ketolysis, further dissociating ketone availability from cancer progression.
Attention then shifted from ketones to fatty acid utilization. When the study introduced intestinal loss of PPARα/δ/γ—transcriptional regulators that drive lipid-responsive gene programs—KD-driven expansion of intestinal stem cells declined. The researchers also observed reductions in proliferation and clonogenic growth, suggesting that KD’s tumor-promoting effects require lipid signaling that reshapes the stem-cell compartment.
Finally, the authors tested whether mitochondrial fatty acid oxidation is the downstream engine. By knocking out CPT1A, an essential gatekeeper for transporting long-chain fatty acids into mitochondria, they found a selective limitation of adenoma formation under KD conditions. This placed fatty acid oxidation of dietary lipids, rather than lipid accumulation or ketone metabolism, at the center of tumor initiation in this setting.
Overall, the work reframes ketogenic nutrition in cancer prevention terms: dietary lipid content can influence intestinal tumorigenesis through fatty acid oxidation pathways even when ketone metabolism is genetically uncoupled. For patients with genetically susceptible intestinal disease, these findings argue for a more nuanced evaluation of dietary strategies that may inadvertently feed oncogenic metabolic circuits.
Subject of Research:
Cancer metabolism; ketogenic diet; intestinal adenomas
Article Title:
Ketogenic diet mediates intestinal tumorigenesis through lipids not ketones
Article References:
Shay, J.E.S., Chi, F., Tzouanas, C.N. et al. Ketogenic diet mediates intestinal tumorigenesis through lipids not ketones. Nature (2026). https://doi.org/10.1038/s41586-026-10779-y
Image Credits:
AI Generated
DOI:
https://doi.org/10.1038/s41586-026-10779-y
Keywords:
ketogenic diet; intestinal cancer; fatty acid oxidation; HMGCS2; CPT1A; PPAR; ketones; stem cells; adenomas
