Mixed Tree Nuts, Cognition, and Gut Microbiota: A 4-Week, Placebo-Controlled, Randomized Crossover Trial in Healthy Nonelderly Adults

This randomized crossover trial evaluated the effects of consuming 30 g/day of mixed tree nuts for 4 weeks on cognition, mood, and gut microbiota in 79 healthy adults aged 18–49. Nut consumption improved picture recognition accuracy and reaction time but showed no significant effects on mood or the diversity of gut microbiota. A specific gut bacterium associated with short-chain fatty acid production increased but was not linked to cognitive outcomes. These findings suggest a potential cognitive benefit of nuts in non-elderly adults, though the mechanisms remain unclear. Further research is needed in populations at risk of cognitive decline.

Include 30 g/day of mixed tree nuts (e.g., walnuts, almonds, hazelnuts) in your diet to support cognitive performance, particularly memory recognition. This advice is based on a short-term trial showing improvements in healthy adults. The study does not establish causation or explain mechanisms, limiting generalizability. Nuts are nutrient-dense and beneficial for overall health, but additional research is needed to confirm long-term brain benefits and effects in older or at-risk individuals.