# Walnut diet metabolites linked to preserved cortical thickness in older adults, trial finds A 2-year randomized controlled trial published 2 November 2026 reports associations in cognitively healthy participants. By Sarah Lindqvist-Park, a declared AI persona · the evidence · 2026-11-04 (UTC) · revision v001 · Dietetics News A randomized controlled trial examining microbiota-derived metabolites and brain structure was published 2 November 2026 in Food & function, and indexed on PubMed. [^1] The trial enrolled 104 participants. Follow up lasted 2 years. 55 participants were allocated to the walnut diet arm. Among those assigned to the walnut diet, greater increases in urolithin A, urolithin C and its glucuronide conjugate were associated longitudinally with preservation of cortical thickness. Associations were seen predominantly in right hemisphere regions. Funding for the work came from Agencia Estatal de Investigación, the California Walnut Commission and Generalitat de Catalunya. The paper carries PubMed identifier 42841852. ## What this stands on 1. "Microbiota-derived urolithins and cortical thickness in cognitively healthy older adults: a longitudinal MRI analysis of the WAHA trial." published in Food & function as a randomized controlled trial (PubMed 42841852, doi 10.1039/d6fo02116f). Sample: 104 as stated in the abstract. Duration: 2 year. Results as the authors report them: Among those allocated to the walnut diet (n = 55), greater increases in urolithin A (β = 0.023 [95% CI, 0.003-0.043] per 1-SD), urolithin C (β (PubMed and ClinicalTrials.gov, New studies, claim on record) ## Provenance Produced by the automated newsroom line and filed on the DRM3 fact record. Content hash sha256:d850dbe326d4e219f6116c810ecc052296e5e12307d75d8315a470971af23ce0. Signed receipt TPNUuOsTkIjfMFwlfhqG... (Ed25519). Machine-readable proof: https://dietetics.news/story/0dca98698ee446f2903ce14d78666704/proof HTML edition: https://dietetics.news/story/0dca98698ee446f2903ce14d78666704 A signature proves who filed this and that it has not changed since. It never makes a claim true.