Study Finds Ketone BHB Directly Suppresses Colorectal Cancer Growth

The headline sounds bigger than the biology, and that is exactly why this paper matters. Researchers sharpened the case that beta-hydroxybutyrate, the ketone body known as BHB, can directly interfere with colorectal cancer growth by shutting down mTORC1, a major nutrient-sensing pathway. That is a real mechanistic advance. It is not, however, proof that keto cures cancer.

The new work, published as a corrected proof in Protein & Cell on March 18, 2026, shows that BHB, specifically the D-form, but not acetoacetate or acetone, was the ketone signal that mattered. The target was RagC, a small GTPase that helps bring mTORC1 to the lysosome, the cellular compartment where the complex gets switched on. In plain English, RagC acts like part of the delivery system for a growth signal. When BHB modifies RagC, that delivery system breaks down.

The study pins the critical change on lysine 349 in humans, K348 in mice. The modification, called beta-hydroxybutyrylation, was catalyzed by p300 and reversed by SIRT1. Once RagC was in this altered state, its active GTP-bound form dropped, its interaction with Raptor and mTOR weakened, and mTORC1 could no longer recruit properly to lysosomes. Since mTORC1 sits at the center of nutrient sensing and growth signaling, that is a plausible brake on tumor expansion.

The effect was not limited to a cell culture curiosity. The paper reports the same pathway in RagC-K348R knockin mice and in colorectal cancer patient-derived samples. That gives the finding more weight than a Petri dish result alone, but it is still preclinical and translational, not a clinical green light for high-fat eating as treatment. It shows one specific ketone-linked mechanism, not a universal dietary cure.

That specificity also fits with the rest of the ketone-and-cancer literature. In 2022, Nature reported that ketogenic diets and BHB suppressed colorectal cancer in mouse models through Hcar2 and Hopx, and the National Cancer Institute summed up that work as a ketone produced by eating keto that may help inhibit colorectal cancer in mice. A 2024 study added another layer, finding BHB resensitized oxaliplatin-resistant colorectal cancer cells, with eight responders and seven nonresponders enrolled in the human arm. In 2025, Nature Communications reported that a ketogenic diet reduced colonic tumor burden in a colorectal cancer mouse model with a humanized microbiome.

Put together, the picture is getting clearer: BHB is not magic, but it is not just fuel either. It can hit different cancer pathways in different contexts, and this RagC-mTORC1 mechanism gives researchers another concrete place to test whether ketone biology can be paired with standard oncology drugs rather than sold as a standalone fix.