Diet and Gut Microbiome Boost Cognition and Lower Biological Age in Older Adults

A systematic review of 15 clinical trials involving more than 4,000 participants over age 45 found that interventions targeting the gut microbiome—such as Mediterranean and ketogenic diets, probiotic or synbiotic supplements, and fecal microbiota transplantation—produced measurable improvements in memory, executive function and overall cognitive performance in older adults with mild cognitive impairment. No significant effects were observed in participants with advanced Alzheimer’s disease.

In a separate four‑week study conducted at the University of Sydney, 104 adults aged 65‑75 were assigned to four dietary patterns ranging from omnivorous to semi‑vegetarian, and from higher‑fat to higher‑carbohydrate. All groups except the omnivorous high‑fat diet showed reductions in an estimated biological‑age score based on biomarkers such as cholesterol, insulin and C‑reactive protein, with the greatest benefit seen in the higher‑carbohydrate omnivorous group. The findings suggest that relatively short‑term shifts toward plant‑forward or lower‑fat meals can quickly influence biological ageing markers in seniors.