Impact of Nut Consumption on Cognition across the Lifespan

Abstract

Cognitive health is a life-long concern affected by modifiable risk factors, including lifestyle choices, such as dietary intake, with serious implications for quality of life, morbidity, and mortality worldwide. In addition, nuts are a nutrient-dense food that contain a number of potentially neuroprotective components, including monounsaturated and polyunsaturated fatty acids, fiber, B-vitamins, non-sodium minerals, and highly bioactive polyphenols. However, increased nut consumption relates to a lower cardiovascular risk and a lower burden of cardiovascular risk factors that are shared with neurodegenerative disorders, which is why nuts have been hypothesized to be beneficial for brain health. The present narrative review discusses up-to-date epidemiological, clinical trial, and mechanistic evidence of the effect of exposure to nuts on cognitive performance. While limited and inconclusive, available evidence suggests a possible role for nuts in the maintenance of cognitive health and prevention of cognitive decline in individuals across the lifespan, particularly in older adults and those at higher risk. Walnuts, as a rich source of the plant-based polyunsaturated omega-3 fatty acid alpha-linolenic acid, are the nut type most promising for cognitive health. Given the limited definitive evidence available to date, especially regarding cognitive health biomarkers and hard outcomes, future studies are needed to better elucidate the impact of nuts on the maintenance of cognitive health, as well as the prevention and management of cognitive decline and dementia, including Alzheimer disease.

Higher versus lower nut consumption and changes in cognitive performance over two years in a population at risk of cognitive decline: a cohort study

“…The observed positive association between nut consumption and cognitive performance is in line with findings from most existing cross-sectional studies, in which nut consumption has been associated with better cognitive performance and a lower risk of cognitive impairment [ 18 ]. Our findings concur in part with the results of prior prospective studies conducted in different middle-aged and older populations, showing that nut consumption was associated with less cognitive decline [ 32 ], better cognitive performance [ 32 , 33 ], and related to a lower risk of cognitive impairment [ [34] , [35] , [36] ].…”

“…The effects of different types of nut consumption (e.g., almonds [ 41 , 42 ], walnuts [ 19 ], and peanuts [ 43 ]) on cognitive performance and cognitive decline in middle-aged and older adults were inconsistent, either showing improvements in cognitive function [ 42 , 43 ] or no effect in delaying cognitive decline [ 19 , 41 ], but in no case was worse cognitive status observed compared with control diets. Some possible reasons for this inconsistency might be due to the duration of the interventions, the sample size studied, the background diets, the sociodemographic-economic and health status of the study populations, and most importantly, the overall risk of cognitive impairment/dementia, as persons at a higher risk (such as the PREDIMED-Plus population) are those that can benefit most from an intervention with neuroprotective agents such as certain nut components [ 18 , 19 , 39 , 40 ].…”

“…Epidemiological evidence for the association between nut consumption and cognitive performance is limited. Most cross-sectional studies have supported a positive relationship between nut consumption and cognitive function [ 7 , 17 , 18 ]. However, results from prospective studies of the association between nut consumption and cognitive decline or changes in cognitive performance over time have been inconsistent [ 7 , 17 , 18 ].…”

“…Most cross-sectional studies have supported a positive relationship between nut consumption and cognitive function [ 7 , 17 , 18 ]. However, results from prospective studies of the association between nut consumption and cognitive decline or changes in cognitive performance over time have been inconsistent [ 7 , 17 , 18 ]. Similarly, randomized clinical trials (RCTs) examining the effects of nut intake on cognitive outcomes are few, and results have been inconsistent, showing either beneficial or no effects on cognitive decline [ 7 , 17 , 18 ].…”

“…Overall, evidence to date regarding the beneficial impact of nut consumption on cognitive function and/or cognitive decline remains inconclusive, though more favorable outcomes tend to be observed in populations at a higher risk of cognitive decline and dementia (e.g., older age, less education, obesity, cardiometabolic risk, etc.) [ 18 , 19 ]. Therefore, to establish nut-related dietary strategies to prevent or delay cognitive decline and eventually dementia, further investigation targeting populations at high risk is warranted.…”