Insights & Discussion
Polyphenolic compounds found in walnuts not only reduce the oxidant and inflammatory load on brain cells but also improve interneuronal signaling, increase neurogenesis, and enhance sequestration of insoluble toxic protein aggregates.
In conclusion, age-related increases in oxidative stress and inflammation, especially when coupled with metabolic and cardiovascular dysfunction, lead to neurodegeneration and cognitive decline. This process of brain aging occurs even in the absence of specific neurodegenerative diseases. Although most chronic neurodegenerative diseases cannot currently be cured, preventive measures earlier in life can protect cognitive function in old age and may prevent or delay the onset of debilitating neurodegenerative diseases. Dietary interventions provide a safe and palatable means of modifying the body's internal environment and, importantly, the neuronal environment within the brain. Walnut polyphenols and tocopherols can reduce oxidative stress and inflammation; furthermore, PUFAs help maintain neuronal membrane integrity and attenuate protein aggregation involved in AD. In rodent studies, the addition of dietary walnuts, equivalent to a single serving of walnuts for humans, was sufficient to improve both motor and cognitive behavior in aged animals. In humans, the inclusion of walnuts in the diet improved cardiovascular health, which is itself a risk factor for neurodegenerative diseases and age-related cognitive decline. Taken together, this evidence suggests that the integration of walnuts into a healthy diet could be an effective means of prolonging health spans, slowing the processes of brain aging, and reducing the risk of chronic neurodegenerative disease.
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The existing evidence, although with low level of confidence, suggests that walnut intake may have a beneficial effect on cognition-related outcomes, including cognitive function, mood, and stroke.
2021 Annals of Medicine Walnut intake, cognitive outcomes and risk factors: a systematic review and meta-analysis Cahoon, D., Shertukde, S. P., Avendano, E. E., et al.
Systematic Review Alzheimer's Disease Dementia Stroke
The existing evidence, although with low level of confidence, suggests that walnut intake may have a beneficial effect on cognition-related outcomes, including cognitive function, mood, and stroke. Limitations in study design and comparability render the available evidence insufficient to draw a firm conclusion regarding the effects of walnut on cognition in adults. High quality studies and standardized interventions and measurement tools are necessary to determine the role of walnut intake in cognitive health.
These reports suggest the benefits of a walnut-enriched diet in brain disorders and in other chronic diseases, due to the additive or synergistic effects of walnut components for protection against oxidative stress and inflammation in these diseases.
2020 Nutrients Beneficial Effects of Walnuts on Cognition and Brain Health Chauhan A, Chauhan V.
Systematic Review Alzheimer's Disease Brain Health Cognitive Function
Walnuts contain several components that have antioxidant and anti-inflammatory effects. Animal and human studies from our and other groups suggest that supplementation with walnuts in the diet may improve cognition and reduce the risk and/or progression of mild cognitive impairment and Alzheimer's disease.
Furthermore, several animal and human studies have suggested that walnuts may also decrease the risk or progression of other brain disorders such as Parkinson’s disease, stroke, and depression, as well as of cardiovascular disease and type 2 diabetes. Together, these reports suggest the benefits of a walnut-enriched diet in brain disorders and in other chronic diseases, due to the additive or synergistic effects of walnut components for protection against oxidative stress and inflammation in these diseases.