This research shows that overweight and obese individuals have higher levels of a toxic compound called quinolinic acid in their bodies, which is linked to memory problems and brain shrinkage. The good news is that butyrate, a substance naturally produced by gut bacteria when we eat fiber, can protect against these harmful effects. Butyrate works by activating genes that produce brain-derived neurotrophic factor (BDNF), a protein essential for brain health and memory formation. The study suggests that increasing butyrate through diet or supplements could help prevent cognitive decline associated with obesity.