Preserving cognitive health as lifespan expands is one of the most important factors for maintaining a high quality of life. A primary underlying mechanism of neurodegenerative disease involves chronic neuron degeneration stemming from impaired neuronal function and viability, eventually prompting cell death. Key contributors to diminished neuronal vulnerability are associated with energy deficits, and include mitochondrial dysfunction, suppressed glucose utilization, and attenuated uptake of branched-chain amino acids (BCAAs). As mitochondria age, oxidative phosphorylation and corresponding ATP generation decline. A notable rise in reactive oxygen species occurs that potentiates oxidative stress and neuroinflammation. Pro-inflammatory cytokines stimulate microglia, the activation of which triggers astrocyte disruption. Since astrocytes facilitate glutamate clearance and neuronal metabolism, any compromise to their integrity induces excitotoxic stress and further exacerbates an inflammatory cascade.
Studies suggest that excess glucose and BCAAs in circulation promote the protein glycosylation, tau phosphorylation, and neurotoxic protein tangles commonly seen in neurodegenerative conditions. Metabolic dysfunction, oxidative stress, and stimulation of inflammatory signaling pathways further provoke progressive accumulation of damaged, misfolded proteins and other debris. A dysregulated immune system is slow to identify and remove neurotoxic substances and autophagy lags. Age-associated changes in epigenetic marks influence the expression of genes related to the stress response. Finally, the incidence of microbial dysbiosis increases with age and is correlated with translocation of bacterial cell wall components through the intestinal lining. These noxious compounds disrupt the blood-brain barrier and amplify neuroinflammation.
One approach aimed at restoring metabolic flexibility, energy availability, and inflammatory tone is the ketogenic diet. While diet was initially discovered as a therapeutic for epilepsy, it has since been repurposed in the treatment of many other conditions associated with metabolic impairment. The ketogenic diet elicits similar physiological adaptations as the fasted state, but in the absence of severe caloric restriction. Typically comprised of 80% energy from fat, 15% from protein, and 5% from carbohydrates, the ketogenic diet depletes glucose stores and forces the body to derive its energy from the production of ketone bodies. As the ketogenic diet is a mimetic of starvation, it stimulates an adaptive stress response by stimulating sirtuin-1 (SIRT1), hypoxia-induced factor 1α (HIF-1α), and AMP-activated protein kinase (AMPK), all while inhibiting mammalian target of rapamycin complex 1 (mTORC1). This serves to upregulate cell clearance pathways including autophagy and protein aggregate removal, enhance metabolic efficiency, prompt mitochondrial biogenesis, quell oxidative stress and neuroinflammation, and modulate gut microbial activity.
The pronounced shift to a fat burning state reduces glycolytic flux and corresponding electron transport chain activity which is a key contributor to reactive oxygen species generation. Since aging is associated with a decline in glucose utilization, the burning of ketones can restore energy balance, improve insulin sensitivity, and attenuate oxidative stress. Futhermore, excess glucose potentiates the glycosylation of proteins and subsequent protein tangles that are strongly correlated with neuronal excitotoxicity and neurodegeneration. Ketosis also increases the breakdown of BCAAs to replenish the energy pool. The depletion of glucose and BCAAs prevents the metabolic consequences that otherwise intensify neuroinflammation.
β-hydroxybutyrate (BHB) is one of the predominant circulating ketone bodies during the ketogenic state and displays pronounced signaling activity. It has been studied for its effect on epigenetic modulation as well as NLRP3 and NF-kB immune and inflammatory signaling inhibition. Furthermore, BHB triggers SIRT1 which acts to amplify expression of antioxidant enzymes, restrict apoptosis, and promote neuronal survival. The ketogenic diet has also been observed to stimulate Nrf2, a master regulator of cellular antioxidant systems and detoxification. Ketosis leads to a rise in neurotrophic factors, notably brain-derived neurotrophic factor, that are critical for synaptic plasticity and neuronal viability. Finally, the ketogenic diet is associated with repression of pro-inflammatory cyclooxygenase-2, inducible nitric oxide synthase, and the cytokines IL-1β, IL-2, IL-4, IL-6 and TNF-α. These effects culminate in more robust antioxidant defense, restoration of redox balance, enhanced mitochondrial function, preservation of neurons, and suppression of inflammation.
Ketone bodies also appear to influence the microbiome. Elevated levels of ketone bodies in the blood have been correlated with diminished growth of Bifidobacterium and other pro-inflammatory bacteria along with proliferation of Lactobacillus, Enterobacteriaceae, and Akkermansia muciniphila, species that support the intestinal lining and promote short-chain-fatty acid production. Reduced presence of pro-inflammatory Th-17 cells in the intestines has additionally been noted. Maintenance of the integrity of the gut barrier prevents translocation of bacterial cell wall components, undigested nutrients, and other harmful compounds that set off an immune and inflammatory cascade. Lipopolysaccharides are endotoxins shed from gut bacteria that can migrate to the brain, damage the blood-brain barrier, and cause severe neuroinflammation and neurotoxicity. Therapeutic redistribution of microbial composition to achieve eubiosis may thereby alleviate gut-brain axis dysfunction and related cognitive deficits.
While the benefits of the ketogenic diet in the context of neurodegenerative conditions are backed by strong mechanistic underpinnings, implementation remains a challenge. Patient adherence is compromised due to strict and complex dietary requirements that may result in feelings of social isolation, undesirable side effects, and mental fatigue. The diet can be difficult to habituate to initially, with frequently reported headaches, fatigue, and gastrointestinal distress that subside as the body adapts to burning fat as its primary fuel source. Extremely low carbohydrate intake can induce vitamin and mineral deficiencies that may necessitate supplementation. Some individuals may also experienced elevations in lipid parameters that can predispose to cardiovascular risk. Other long term impacts may include anemia, neuropathy, poor bone mineral density, and kidney and liver abnormalities. It is subsequently critical that the diet be personalized so as to mitigate untoward side effects while optimizing adherence. More studies are needed to fully comprehend the long-term effects and establish ideal implementation strategies.
Salgueiro AM, Ferreira-Marques M, Ribeiro RFN, et al. Ketogenic diet as a therapeutic strategy for neurodegenerative diseases: from mechanisms to translational challenges. Transl Neurodegener. 2026;15(1):24. Published 2026 May 25. doi:10.1186/s40035-026-00557-1