Question explored with the scientific record
What does the clinical trial evidence show about ketogenic or metabolic diets as an adjunct in glioblastoma?
The clinical trial evidence for ketogenic diets in glioblastoma shows the diet is feasible and safe to add to standard care, but no trial has proven it extends survival.
The best available evidence comes from a 2025 systematic review that pooled several small, mostly single-arm studies [1]. The largest controlled trial was a randomized feasibility study of only 11 patients, and 5 of them dropped out before completing it [1, 2]. That study reported a median overall survival of 12.8 months from diagnosis, which is shorter than the roughly 15 months expected with standard care alone [2, 3]. Another pilot study of 9 patients with recurrent glioblastoma reported a median survival of 32 weeks from diet initiation, but had no control group to compare against [1].
| Study | Design | Patients started | Patients completed | Median survival |
|---|---|---|---|---|
| ERGO 2014 (recurrent GBM) | Single-arm pilot | 9 | Not reported | 32 weeks from diet start |
| KEATING 2019 (newly diagnosed) | Randomized feasibility | 11 | 6 | 12.8 months from diagnosis |
| Klein 2020 (primary GBM) | Non-randomized, two KD arms | 8 | 5 | 20 weeks from diet start |
The evidence is thin and low-quality. Every study was small, most had no control group, and the one that did had a survival outcome that did not beat the historical standard. The 2025 systematic review concluded that no definitive efficacy conclusions can be drawn and called for larger, uniform trials [1]. A separate 2021 systematic review across all cancers found no clear anti-tumor survival benefit from ketogenic diets [2].
My call: The evidence does not show that adding a ketogenic diet to standard glioblastoma treatment improves survival. The diet appears feasible and safe in the short term, but the survival numbers from the available trials are not better than what is expected from standard care alone. Confidence: low — the studies are too small and uncontrolled to rule out either a modest benefit or a modest harm.
Sources used 3
-
Efficacy of ketogenic metabolic therapy as an adjuvant to the current standard of care in the treatment of glioblastoma: A systematic review of clinical trials
A PRISMA-guided systematic review assessing ketogenic metabolic therapy (KMT) as an adjuvant to standard therapy for glioblastoma, finding feasibility and safety across small, heterogeneous studies but no definitive efficacy conclusions due to lack of standardized protocols and …
DOI: 10.1007/s12032-025-03165-7 -
The use of ketogenic diets in cancer patients: a systematic review
This systematic review evaluates ketogenic diets in cancer patients, finding largely heterogeneous, low-quality clinical evidence with no clear anti-tumor survival benefit, mixed effects on quality of life, notable weight loss and adherence challenges, and a need for robust rand…
DOI: 10.1007/s10238-021-00710-2 -
Ketogenic diet treatment as adjuvant to standard treatment of glioblastoma multiforme: a feasibility and safety study
Feasibility and safety of adding a ketogenic diet to standard chemoradiation for glioblastoma multiforme were demonstrated in a small, single-center prospective study, with most participants achieving ketosis and tolerating the regimen well.
DOI: 10.1177/1758835919853958