# Ketogenic diets in glioblastoma

Source: https://onco.cc/technologies/ketogenic-diet-glioblastoma/  
OnCo record `ketogenic-diet-glioblastoma` (Technology). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

A ketogenic diet restricts carbohydrate so the body runs on ketones, on the theory that glioblastoma cells depend on glucose while neurons can burn ketones. Small trials show it is safe and achievable for three to six months with supervision, but none has shown a benefit against the tumour, and adherence beyond three months is poor.

## Summary

Glioblastoma cells rely heavily on glycolysis, whereas normal brain can use ketone bodies, so a ketogenic diet has a plausible rationale that mouse models partly support. Human evidence is limited to feasibility studies and small randomised trials: the ERGO trial (recurrent GBM, feasibility), ERGO2 (50 patients, calorie-restricted ketogenic diet plus fasting during re-irradiation, no PFS benefit), KETOCAN and modified Atkins studies with temozolomide and radiotherapy showing achievable ketosis and acceptable tolerability but no efficacy signal that survives scrutiny. Adherence beyond three months is poor, weight loss is common, and steroid-induced hyperglycaemia undermines ketosis. The honest position is that it is an open question with a weak prior, not a treatment, and patients who choose it should do so inside a trial with dietitian support.

## Fields

- Kind: Technology
- Status: phase-2
- Last checked: 2026-09-08
- Principle: Carbohydrate restriction lowers blood glucose and raises ketones; the hypothesis is that tumour cells with mitochondrial dysfunction cannot oxidise ketones efficiently while neurons can.
- Strengths: Feasible and safe for most patients over 3-6 months with supervision; Testable biomarker (ketosis); Plausible synergy with radiotherapy and PI3K-pathway drugs
- Limitations: No randomised evidence of survival benefit; Adherence and weight loss; Heavily marketed to patients ahead of the evidence

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Ketogenic_diet
- ERGO2 (Int J Radiat Oncol Biol Phys 2020): https://doi.org/10.1016/j.ijrobp.2020.06.021

## Connected records

- ideas: [Ask about diet at diagnosis, and prebunk the myths before the internet does](https://onco.cc/ideas/idea-nl-ask-about-diet-prebunking/), [One definitive ketogenic diet trial in glioblastoma, then stop](https://onco.cc/ideas/idea-nl-ketogenic-gbm-definitive-trial/)
- cancers: [Glioma & glioblastoma](https://onco.cc/cancers/glioblastoma/)
- fronts: [Diet, Exercise & Lifestyle](https://onco.cc/fronts/nutrition-lifestyle/)
- technologies: [Metabolic therapy: starving the tumour of a nutrient](https://onco.cc/technologies/metabolic-therapy/)
- drugs: [Temozolomide](https://onco.cc/drugs/temozolomide/)
- pathways: [PI3K / AKT / mTOR](https://onco.cc/pathways/pi3k-akt-mtor/)
- terms: [Glycaemic index and glycaemic load](https://onco.cc/terms/glycaemic-index/), [Metabolic theory of cancer: from Warburg to oncometabolites](https://onco.cc/terms/metabolic-theory-of-cancer/), [Unproven diet claims (alkaline, juice, 'anti-cancer' diets)](https://onco.cc/terms/unproven-diet-claims/), [Warburg effect](https://onco.cc/terms/warburg-effect/), [Warburg-effect diet claims ('sugar feeds cancer')](https://onco.cc/terms/warburg-effect-diet-claims/)
- trials: [ERGO2: ketogenic diet and fasting during re-irradiation of recurrent glioma](https://onco.cc/trials/ergo2/)
- bottlenecks: [Failures are hidden](https://onco.cc/bottlenecks/b-negative-results/), [Misinformation and unproven therapies](https://onco.cc/bottlenecks/b-misinformation/)
- key papers: [ERGO2: A Prospective, Randomized Trial of Calorie-Restricted Ketogenic Diet and Fasting in Addition to Reirradiation for Malignant Glioma](https://onco.cc/key-papers/paper-voss-int-j-radiat-oncol-biol-phys/)
- roadmaps: [Diet, exercise and lifestyle roadmap: causes established → interventions that disappointed → exercise proven as treatment](https://onco.cc/roadmaps/nutrition-lifestyle-roadmap/)

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