Procedure
BRAIN
Participants were required to attend the Brain, Performance and Nutrition Research Centre (Northumbria University, United Kingdom) on 5 separate visits. Screening visits took place a minimum of 1 wk prior to the first testing visit. Following informed consent, participants were screened for eligibility, provided demographic data, and had their blood pressure taken. Training on the cognitive tasks involved completing the tasks 5 times to eradicate practice effects. Participants were also given an FFQ (Visits 1–4: Participants refrained from caffeine for a minimum of 10 h, the consumption of alcohol and intake of over-the-counter medication for 24 h, and systemic antihistamines for 48 h prior to each visit. Participants attended the laboratory at an agreed time in the morning following a light breakfast of cereal and/or toast at home 1 h (minimum) before the session commenced, with breakfast standardized across each visit. Prior to test procedures, eligibility criteria and concomitant medications were reviewed, and supplementation and adherence to nut intake restrictions confirmed. A urine sample was then provided, and stool sample collected prior to completion of the mood and cognitive measures (see Schematic of study procedures.