Could a high-fat, low-carbohydrate diet — the same metabolic regimen that pediatric neurologists have used for a century to control drug-resistant epilepsy — protect the brain against Alzheimer’s, Parkinson’s, and other neurodegenerative diseases?
A sweeping review published on May 25 in Translational Neurodegeneration by researchers at the University of Coimbra’s Center for Neuroscience and Cell Biology in Portugal argues that the case is biologically plausible and growing stronger — but remains far from proven in humans.
What the review examined
The paper, “Ketogenic diet as a therapeutic strategy for neurodegenerative diseases: from mechanisms to translational challenges,” is a narrative review that synthesizes dozens of prior studies across five neurodegenerative conditions: Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, amyotrophic lateral sclerosis (ALS), and multiple sclerosis.
It is not a single experimental study. The ScienceAlert headline that the diet “may help protect against multiple brain diseases” is accurate but requires careful unpacking: the review draws heavily on preclinical animal models, with human clinical trial data still limited.
Five proposed mechanisms
The authors identify five molecular pathways by which ketogenic diets — regimens that shift the body from glucose to ketone bodies as its primary fuel source — may exert neuroprotective effects:
1. Ketone bodies as alternative fuel. The brain’s glucose metabolism declines early in Alzheimer’s and other neurodegenerative conditions. Ketone bodies (β-hydroxybutyrate, acetoacetate, and acetone) bypass the impaired glycolytic pathway, providing an alternative energy substrate that can restore neuronal stability and metabolic function. This mechanism has the strongest experimental support, particularly in Alzheimer’s models.
2. Reduced oxidative stress. Ketone bodies decrease production of reactive oxygen species at the mitochondrial level and upregulate antioxidant defenses. The effect is well-documented in cell and animal models.
3. Suppressed neuroinflammation. β-hydroxybutyrate in particular has been shown to inhibit the NLRP3 inflammasome — a protein complex that drives chronic inflammatory signaling in the brain. Rodent models of Parkinson’s disease and multiple sclerosis have demonstrated reduced microglial activation under ketogenic conditions.
4. Autophagy and protein aggregation. The metabolic stress induced by ketosis activates autophagy — the cell’s quality-control machinery that clears misfolded proteins. This is directly relevant to the protein aggregates that define Alzheimer’s (amyloid-β, tau), Parkinson’s (α-synuclein), and Huntington’s (huntingtin).
5. Gut microbiome modulation. The diet alters the composition of gut bacteria, increasing populations associated with anti-inflammatory effects and improved brain function via the gut-brain axis — an emerging but still poorly understood mechanism.
The caveats
The authors are explicit about the limits of the evidence.
“While preclinical studies have demonstrated encouraging results, significant gaps remain in understanding long-term effects, safety, and practicality of [the ketogenic diet] in clinical settings,” they write.
The review characterizes the ketogenic diet as a “complementary metabolic intervention” that “supports disease-specific treatments by enhancing metabolic resilience” — not a standalone therapy.
The practical barriers are considerable. Classical ketogenic diets — 90% fat, strict carbohydrate restriction — are among the most difficult dietary regimens to maintain. Side effects include constipation, insomnia, elevated cholesterol, and, over the long term, potential risks for type 2 diabetes and cardiovascular disease. Modified versions (the modified Atkins diet, MCT oil-based approaches) improve tolerability but may not produce equivalent metabolic effects.
What this means
The review’s strength is its breadth: it connects five neurodegenerative diseases to a shared set of metabolic vulnerabilities. The weakness is that the connections, while biologically plausible, are mostly drawn from animal studies. Rigorous, long-term randomized controlled trials in humans — the kind that could support a clinical recommendation — have not yet been conducted.
For an individual wondering whether a ketogenic diet might lower their risk of Alzheimer’s or Parkinson’s, the honest answer is: maybe, but we don’t know yet. The mechanisms are real. The pathways are conserved across species. But the phrase that matters most comes from the authors themselves — “complementary metabolic intervention” — which is careful academic language for: it could help, but it is not a substitute for what we already know works.
Source: Salgueiro, A.M. et al. “Ketogenic diet as a therapeutic strategy for neurodegenerative diseases: from mechanisms to translational challenges.” Translational Neurodegeneration 15, Article 24 (2026). DOI: 10.1186/s40035-026-00557-1
>
Note: This is a narrative review, not an original experimental study. The individual studies reviewed range from cell culture to animal models to a small number of human pilot trials.