Background and aims

Reduced brain vascular function contributes to age-related cognitive decline. While peanut consumption may improve cognitive performance, the underlying mechanisms remain unclear. This study aimed to investigate the longer-term effects of skin-roasted peanut consumption on brain vascular function and cognitive performance in older adults.

Methods

In a randomized, single-blind, controlled crossover trial, 31 healthy individuals (age [mean ± SD]: 67 ± 4 years; BMI: 26.7 ± 3.3 kg/m2) consumed 60 g/day of unsalted, skin-roasted peanuts or no peanuts (control) for 16 weeks, separated by an 8-week washout. During follow-up, brain vascular function was assessed by quantifying global cerebral blood flow (CBF) using arterial spin labeling magnetic resonance imaging, which was the primary outcome. Cognitive performance was evaluated using the Cambridge Neuropsychological Test Automated Battery (CANTAB).

Results

The consumption of peanuts was well-tolerated and median compliance was excellent: 100 % (interquartile range [IQR] 99–100 %). Compared with control, peanut consumption significantly increased global CBF by 3.6 % (intervention effect: 1.5 mL/100 g/min, 95 % CI [0.3, 2.6], p = 0.014) and gray matter CBF by 4.5 % (2.2 mL/100 g/min, 95 % CI [0.9, 3.6], p = 0.002). Verbal memory improved by 5.8 % during the delayed recall condition of the verbal recognition memory (VRM) task (+1.4 words correct (95 % CI [0.0, 2.7], p = 0.043). No beneficial effects were found in executive function and psychomotor speed outcomes. Systolic blood pressure (−5 mmHg; 95 % CI [-8, −2], p = 0.004) and pulse pressure (−4 mmHg; 95 % CI [-7, −1], p = 0.006) decreased during the peanut intervention.

Conclusions

Daily consumption of skin-roasted peanuts for 16 weeks improved brain vascular function in healthy older men and women. These favorable effects may underlie the observed improvements in verbal memory, highlighting a potential mechanism by which increased peanut intake beneficially affects cognitive performance.