W. Shang, Z. Gu, L. Li, L. Cheng and Y. Hong (2025). Mechanisms of a Ketogenic Diet and High-Carbohydrate Diets on Cognitive Impairment and the Microbiota-Gut-Brain Axis. Nutrition reviews. https://doi.org/10.1093/nutrit/nuaf198

PubMed 41165005

[Abstract]
Cognitive impairment and decreased learning and memory abilities are the primary symptoms of neurodegenerative diseases, such as Alzheimer's disease. They are closely associated with protein aggregation, neuroinflammation, excitatory/inhibitory imbalance, intestinal flora, and metabolism and are affected by different dietary patterns. The ketogenic diet (KD) can provide alternative brain energy through the production of ketone bodies; improve mitochondrial function, antioxidant stress, and inflammation; and regulate neurotrophic factors and neurotransmitter balance, thereby improving cognitive function. The impact of a high-carbohydrate diet (HCD) on brain function depends on its specific dietary formulation. An HCD based on polysaccharides (such as starch) may have a positive impact on cognitive function, while an HCD based on monosaccharides or disaccharides may increase the risk of cognitive impairment. Both a KD and an HCD can influence cognitive function by altering the structure of gut microbiota and regulating metabolites through the microbiota-gut-brain axis. This review summarizes the potential mechanisms of a KD and an HCD on cognitive impairment and the microbiota-gut-brain axis in order to provide a theoretical basis for improving cognitive behavior and intestinal health in patients with encephalopathy from the perspective of a dietary intervention.