Scientific review published in Advances in Nutrition finds some promising evidence, but not enough to make firm conclusions
As we age, our brains become increasingly vulnerable to oxidative stress, chronic inflammation, and vascular impairment. These factors, in turn, may lead to dementia, a condition that currently affects 35.6 million people worldwide. As the population continues to age, this number is projected to double by 2030 and more than triple by 2050.
While some medications may delay the progression of dementia, there is no cure; however, there are modifiable lifestyle factors that can help prevent the onset of dementia, including diet. Studies have shown, for example, that diets rich in foods with anti-inflammatory and antioxidant properties, such as the Mediterranean diet, may slow down cognitive decline and reduce the risk of dementia. It has been suggested that the consumption of nuts, in particular, with their high concentration of monounsaturated and polyunsaturated fats, may play a key role in warding off cognitive decline.
Published in Advances in Nutrition, the international review journal of the American Society for Nutrition, “Nut Consumption for Cognitive Performance: A Systematic Review” assessed the current body of evidence to determine whether, in fact, nut consumption has a positive effect on cognitive performance. Specifically, authors Lauren E. Theodore et al. examined almonds, hazelnuts, macadamias, pistachios, walnuts, pecans, pine nuts, Brazil nuts, cashews, and peanuts and their associations with memory, attention, processing speed, executive function, visual-spatial ability, and cognitive impairment.
In order to conduct their research, the authors performed a comprehensive search of the scientific literature, leading them to 22 scientific studies involving 43,793 participants. Upon analyzing these studies, the authors concluded, “lack of consistency across the studies regarding study design, type of nut used, and cognitive outcomes measured resulted in inconsistent evidence that the regular consumption of mixed nuts has a protective effect on cognition in adults of different ages.” Nonetheless, studies targeting populations with a higher risk of cognitive decline, including people at higher risk for cardiovascular disease, tended to find more favorable outcomes. According to the authors, “these findings imply that individuals at higher risk of cognitive decline may obtain the largest benefit from nut consumption.”
While the link between overall nut consumption and cognition was inconsistent, the Advances in Nutrition review did find stronger evidence to support the association between walnut consumption and better cognitive performance among young, middle-aged, and older adults. Walnuts contain unique nutritional properties, including a high omega 3 to omega 6 fatty acid ratio and an exceptional concentration of polyphenols. These nutrients are believed to contribute to walnuts’ neuroprotective capacity by lowering neuroinflammation and oxidative stress. The authors did, however, note that “more studies are required to elucidate whether walnuts provide a superior advantage over other nuts.”
Will eating nuts help you ward off cognitive decline? Despite some promising studies, more research is needed to fully answer that question.
References
Theodore LE, Kellow NJ, McNeil EA, Close EO, Coad EG, Cardoso BR. Nut Consumption for Cognitive Performance: A Systematic Review. Advances in Nutrition, nmaa153 (Epub ahead of print; DOI: https://doi.org/10.1093/advances/nmaa153).
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