A recent study published in The Journal of Nutrition reported that consumption of mixed tree nuts for 4 weeks had a positive effect on cognition in healthy nonelderly adults as well as upregulation of a microbial class associated with gut health.

Cognitive impairment is a growing worldwide health concern as our population ages.  In the absence of effective pharmaceutical treatments, modifiable lifestyle factors such as nutrition represent crucial targets in preventing cognitive decline.  Nuts beneficially modulate a broad spectrum of parameters including cardiometabolic function, lipid profile, and weight gain; all of which have the potential to impact cognition. Alterations to gut microbiota have also been highlighted as a potential mechanism for diet-induced changes to cognition. Consumption of nuts has been linked to better cognition in those aged 20 – 90 years. However, a lack of association between nut consumption and cognitive decline suggests that early nutritional intervention may be needed to ensure a positive impact on cognitive decline in older age.  To bridge this knowledge gap, Crystal Haskell-Ramsay (Northumbria University) and colleagues examined the effects of daily consumption of tree nuts for 4 weeks on cognitive function, mood, metabolic responses, and gut microbial species in healthy, nonelderly adults. 

This randomized, placebo-controlled double-blind crossover study assessed the effects of 4 weeks of supplementation with 30 grams/day mixed tree nuts versus placebo on cognition and mood in 79 healthy adults aged 18-49 years.  Cognitive tasks were chosen to cover a range of cognitive domains including memory, attention, and executive function. Metabolic responses, gut bacterial community structure, and the potential for these to impact cognition were explored.

Study results indicate that the consumption of mixed tree nuts for 4 weeks led to improvements on a picture recognition task in healthy nonelderly adults. This was accompanied by enrichment of a microbial class associated with gut health but limited changes to urinary metabolites. This is the first study to show effects of a whole food on cognition and gut bacteria within the same study.  The finding of improved picture recognition adds to a growing body of literature showing positive effects of nuts on cognition.  It is possible that more profound effects may be shown with higher quantities of nuts or in those at risk, such as those experiencing cognitive decline or in those experiencing an imbalanced gut ecosystem.


Haskell-Ramsay CF, Dodd FL, Smith D, Cuthbertson L, Nelson A, Lodge JK, Jackson PA. Mixed Tree Nuts, Cognition, and Gut Microbiota: A 4-Week, Placebo-Controlled, Randomized Crossover Trial in Halthy Nonelderly Adults.  The Journal of Nutrition, Volume 152, Issue 12, December 2022, Pages 2778-2788. https://doi.org/10.1093/jn/nxac228.

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