Effects of a 4-week pecan-enriched diet on cognitive function in healthy older adults

BACKGROUND: Pecans are rich in nutrients known to benefit cognition. OBJECTIVE: To examine the effect of daily pecan consumption on cognitive function in older adults. METHODS: In this randomized controlled trial, 42 adults (50–75y) either consumed 68 g of pecans/day for 4 weeks (pecan; n = 21) or avoided all nuts (control; n = 21). At pre- (V1) and post-intervention (V2) visits, cognitive function was assessed using a fluid composite score and four subtests from the NIH toolbox cognitive battery (NIHTB-CB) (Flanker Test, Digital Change Card Sort Test (DCCS), Picture Sequence Memory Test (PSMT), NIHTB Auditory Verbal Learning Test (RAVLT)) at fasting, 30- and 210-min after a high saturated fat meal void of pecans. RESULTS: From V1 to V2, fasting and postprandial cognitive performance did not differ between groups. There were improvements in both groups for fasting fluid composite score (p <  0.001) and performance on RAVLT, PSMT, DCCS, and Flanker tests from V1 to V2 (p <  0.001 for all), with no differences between groups. Additionally, postprandial performance on RAVLT, PSMT, and Flanker tests improved at V2 (p <  0.01 for each), with no differences between groups. CONCLUSIONS: A short-term pecan-enriched diet did not provide additional cognitive benefits in healthy older adults in the fasted or postprandial state.