Oral administration of butyrate, a short-chain fatty acid produced when gut bacteria ferment dietary fiber, blocked the buildup of amyloid-beta protein in the gut, brain and bloodstream of mice bred to develop an Alzheimer's-like disease, and also eased brain inflammation and preserved memory performance in the animals, according to a study published in Molecular Psychiatry on March 5, 2026. The research, led by Rodrigue Brossaud and colleagues, used the SAMP8 mouse strain, a model of age-related cognitive decline that develops amyloid pathology without genetic engineering.
The researchers found that amyloid pathology and nerve damage appeared first in the gut, not the brain. By two months of age, months before any memory problems emerged, SAMP8 mice already showed reduced levels of two proteins, EphB2 and synaptophysin, that enteric neurons, the nerve cells lining the digestive tract, need to form working connections; gut tissue also showed higher activity of BACE1, an enzyme that helps generate amyloid-beta, and lower levels of neprilysin, an enzyme that clears it. The team reproduced the same pattern of nerve damage when they exposed amyloid-beta directly to human intestinal tissue grown from stem cells and to explanted samples of human colon, indicating the vulnerability is not limited to mice.
When researchers added butyrate directly to isolated enteric neurons, it reversed the amyloid-driven loss of EphB2 and synaptophysin in a dose-dependent way and lowered the proteins that generate amyloid-beta in those cells; the effect was traced to protection of synaptic machinery inside the enteric neurons themselves, not to the vagus nerve's sensory signaling pathway that has featured in earlier gut-brain amyloid research. In live mice, sodium butyrate was added to drinking water from weaning and continued for five months in groups of 10 to 15 animals; treated SAMP8 mice had less amyloid pathology in gut and brain tissue and in blood plasma, calmer markers of brain inflammation, and better performance on memory tests than untreated SAMP8 mice, the paper and an accompanying Nature Reviews Neurology research highlight, published April 10, 2026, reported.
The findings come entirely from a mouse model, cultured neurons, and human gut tissue studied outside the body; no person has taken butyrate in this research, and the paper does not test whether a fiber supplement, probiotic, or dietary change alters amyloid pathology or memory in people with or at risk of Alzheimer's disease.