Mixed Tree Nuts, Cognition and Gut Microbiota: a 4-week, Placebo-Controlled, Randomized Crossover Trial in Healthy Non-Elderly Adults

Haskell-Ramsay, Crystal, Dodd, Fiona, Smith, Darren, Cuthbertson, Lewis, Nelson, Andrew, Lodge, John and Jackson, Philippa (2022) Mixed Tree Nuts, Cognition and Gut Microbiota: a 4-week, Placebo-Controlled, Randomized Crossover Trial in Healthy Non-Elderly Adults. Journal of Nutrition. ISSN 0022-3166 (In Press)

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Official URL: https://doi.org/10.1093/jn/nxac228

Abstract

Background
Beneficial effects of nut supplementation on cognitive function have previously been demonstrated in young and older adults. Alterations to gut microbiota have also been shown following tree nut consumption. However, no data exists on the effects of nuts on cognition and intestinal microbial communities assessed within the same study.

Objectives
The study aimed to examine the effects of daily consumption of tree nuts for four weeks on cognitive function (primary outcome), mood, metabolomics, and gut microbial species (secondary outcomes) in healthy, non-elderly adults.

Methods
This randomized, placebo-controlled, double-blind, counterbalanced crossover study assessed the effects of four weeks’ supplementation with 30 g/d mixed tree nuts versus placebo on cognition and mood in 79 healthy 18–49 year old adults. Metabolic responses, gut bacterial community structure and the potential for these to impact cognition were explored using a multi-omic approach. Bacterial community analysis was conducted in QIIME2.

Results
Mixed model analysis indicated that nut consumption led to significant improvements to accuracy (placebo M = 92.2% vs. NUTS M = 94.5%; p = 0.019) and speed of response (placebo M = 788 ms vs. NUTS M = 757 ms; p = 0.004) on a picture recognition task. No significant changes to bacterial community alpha or beta diversity were observed when comparing nut consumption to the placebo arm. However, an unclassified Lachnospiraceae amplicon sequence variant (ASV) was significantly enriched in participants when supplemented with nuts (p = 0.015). No correlations were observed between the changes to picture recognition and the changes to the unclassified Lachnospiraceae ASV. There were no significant changes to the urinary metabolome.

Conclusions
These findings indicate a positive effect of nut on cognition following only 4-weeks’ consumption in a healthy non-elderly sample, as well as upregulation of a microbial taxa associated with gut health. The effects appear to be independent of one another, but further exploration is required in those experiencing cognitive decline and/or gut dysbiosis.

The study was registered at clinicaltrials.gov (identifier: NCT03500601).

Item Type: Article
Additional Information: Funding information: This study was supported by funding from the INC International Nut and Dried Fruit Council.
Uncontrolled Keywords: metabolomics, healthy adults, cognitive function, cognition, mood, gut microbiota, nuts
Subjects: C800 Psychology
D600 Food and Beverage studies
Department: Faculties > Health and Life Sciences > Applied Sciences
Faculties > Health and Life Sciences > Psychology
Depositing User: Rachel Branson
Date Deposited: 07 Oct 2022 09:05
Last Modified: 15 Nov 2022 16:15
URI: https://nrl.northumbria.ac.uk/id/eprint/50319

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