“Are nuts truly beneficial for brain health?” ponders experts. The impact of one’s diet on health is a crucial aspect, with the ability to modify various lifestyle factors and regulate potential risks for certain health conditions.
Peanuts and tree nuts, enriched with abundant nutrients and possessing anti-inflammatory and antioxidant properties, are believed to hold potential neuroprotective effects. The presence of diverse nutrients and active compounds in nuts seems to contribute to this phenomenon. However, the existing epidemiological evidence concerning the relationship between nut consumption and cognitive performance remains limited and inconclusive.
Cognitive function and nut consumption appear to be positively linked according to numerous cross-sectional studies. However, conflicting results have emerged from prospective studies and randomized controlled trials (RCTs). Consequently, the impact of nut intake on cognitive performance remains a topic of ongoing debate.
In a recent study, researchers sought to prospectively examine the associations between nut consumption and changes in cognitive performance over a two-year period in a Spanish cohort of older adults at risk of cognitive decline. The study included individuals aged 55 to 75, residing in the community, and categorized as overweight or obese with metabolic syndrome at the beginning of the study.
Participants were required to complete a food-frequency questionnaire that assessed their habitual intake of various food items over the past year. Nut consumption was categorized into four groups: less than one serving per week, one to two servings per week, three to six servings per week, and seven or more servings per week. Trained personnel evaluated cognitive performance at the beginning of the study and again after two years.
During personal interviews, participants underwent eight neuropsychological tests. These tests were standardized to generate a z-score for each participant using the mean and standard deviation of baseline data. By estimating the difference in scores, the researchers aimed to investigate changes in cognitive performance. Composite measures were calculated to provide a global assessment of cognitive function and three cognitive domains: general cognition, executive function, and attention.
The primary outcome of interest was the change in composite scores over the two-year period. Baseline data on sociodemographics, lifestyle, food consumption, medical history, and anthropometrics were also collected. Additionally, the Beck Depression Inventory was used to assess depressive symptoms. The associations between nut consumption and changes in cognitive function over two years were examined using multivariable linear regression models.
The study enrolled a total of 6,630 participants, with an average age of 65, and females representing 48.4% of the cohort. At baseline, the lowest and highest consumption categories reported daily average nut consumption of 1.7 g and 43.7 g, respectively, with walnuts being the most commonly consumed variety. Individuals with the highest nut consumption demonstrated higher education levels, greater adherence to the Mediterranean diet, and increased physical activity compared to those with the lowest intake.
Furthermore, the highest consumption category included fewer current smokers and individuals experiencing depressive symptoms. Additionally, participants with the highest nut intake exhibited lower waist circumference and body mass index (BMI) compared to those with the lowest intake.
The findings of the study unveiled a positive association between nut consumption and changes in cognitive performance over the two-year period. Multivariable models demonstrated that consuming one serving of nuts daily was linked to more favorable changes in general cognitive function and the clock drawing test (CDT).
Moreover, individuals consuming three to six servings of nuts per week experienced better evolution of cognitive performance over two years compared to those consuming less than one serving per week. However, this favorable association was not observed in the highest category of nut consumption. Similar results were obtained in sensitivity analyses.
Notably, the researchers did not observe significant interactions between nut intake and education level, sex, smoking status, hypertension, hypercholesterolemia, or type 2 diabetes.