Effect of Walnuts on Cognitive Function and Gut Microbiome in Older Adults

Inclusion Criteria: * Age 55 years or older * Able to hear well enough to understand spoken instructions and questions * Able to see well enough to read and respond to printed instructions and fill out questionnaires (corrective lenses are allowed) * Able to write legibly and move a computer joystick with at least one hand (i.e., no injury or connective tissue or joint disorder that would impair ability to write or make hand movements) * Able to speak, read, and understand English * Score of greater than 79 on water maze learning task * Willing to maintain current eating patterns * Willing and able to complete the cognitive tests * Willing to stop consuming almonds, Brazil nuts, cashews, chestnuts, hazelnuts, macadamia nuts, peanuts, pecans, pistachios, walnuts, persimmons and pomegranates for 14 weeks. - are nuts or contain ellagitannins or ellagic acid - compounds/foods of interest for this study * Willing to limit oak aged wines and spirits to 1 serving/day and limit blackberries (including similar berries like boysenberries, marionberries, and olallieberries), cloudberries, cranberries, currants, elderberries, lingonberries, raspberries, strawberries, wolfberries, other native berries; guava, mango, muscadine grapes, nectarines, peaches, plums, pluots to 1 cup/day for 14 weeks; REMAIN CONSISTENT (consistent intake levels of): Coffee, tea, apple, apricots, blueberries, cherries, grapes (table/common) * Willing to stop probiotic supplements 2 weeks prior to and during the …