The Global Grant for Gut Health

This observational cross-sectional study involves 255 older adults and aims to investigate how plasma food‑ and microbiota‑derived metabolites modulate intestinal barrier function, and how these mechanisms influence neurocognitive ageing. The specific objectives of the study are to: i) characterize the taxonomic and functional profiles of the gut microbiota using shotgun metagenomics; ii) map plasma food‑ and microbiota‑derived metabolites and quantify biomarkers of intestinal barrier integrity; iii) identify plant and animal food species from residual dietary DNA in stool samples through DNA metabarcoding; iv) integrate clinical and behavioural data with multi‑omics approaches—including metagenomics, metabolomics, metabarcoding, and neuroimaging—to explore causal pathways underlying the complex diet–gut–brain axis.