Affordable daily supplements are altering scientific perspectives on connections between the digestive system and cognitive health. A 2024 twin study in Nature Communications showed that protein and prebiotic supplements taken daily improved memory scores among adults over 60. The research has prompted additional trials exploring potential protection against dementia. Later that year, researchers at Wageningen University in the Netherlands began the PRECODE trial examining gut-brain effects of prebiotics in older adults with possible cognitive issues. This marks the first human investigation of three dietary fibers—inulin from chicory, resistant dextrin, and seaweed polysaccharide—against a maltodextrin placebo. Participants over 60 consume the fibers twice daily in beverages for 26 weeks while undergoing brain scans and cognitive assessments. Results are expected in 2027. Inulin featured in the earlier twin research. That double-blind study tested two low-cost plant-fiber prebiotics available without prescription. The second, fructooligosaccharide, serves as a natural sweetener. Scientists at King’s College London recruited 36 twin pairs aged at least 60. One twin in each pair received prebiotic mixed with protein powder daily, while the other got placebo. Those receiving inulin or fructooligosaccharide scored higher on cognitive tests after three months. The supplements also produced minor microbiome shifts, including higher levels of Bifidobacterium. Rodent studies indicate this bacterium may lessen cognitive problems via gut-brain pathways. Researchers expressed optimism about rapid changes within 12 weeks and potential benefits for aging populations. Twin registries help separate genetic from environmental influences on health. Prior animal work suggests high-fiber supplements nourish colon bacteria linked to better cognition in rodents and people. Growing evidence supports gut-brain links, with some experts calling the gut a second brain. The King’s College study suggests certain dietary fibers could aid cognitive decline treatment. Experts noted the fibers are inexpensive, accessible, and safe. Follow-up work will examine longer-term effects in larger groups, which the PRECODE trial aims to do by evaluating the microbiota-gut-brain axis in at-risk older adults.
