This study is being conducted to assess the effect of dietary blueberry supplementation vs. placebo on measures of cognition and mobility in older adults. Participants will visit the HNRCA on 4 occasions. During the first visit, participants will complete a dietary assessment and familiarize themselves with some of the cognitive tests used in the study. After a period of up to 45 days participants will return for the second visit. Participants will be randomized to consume either freeze dried blueberry powder or a placebo powder that tastes like blueberry. At visits 2, 3 and 4, participants will undergo tests of cognition, memory, gait and balance. In addition, blood samples and 24-hour urine will be collected at these visits. Tests include balance and gait assessment using a treadmill instrumented with pressure sensors which will measure postural sway and a variety of spatial/temporal gait parameters. Participants will also be affixed with surface electrodes to measure the activation of muscles in their legs during these balance and gait measurements. Participants will complete a battery of cognitive tests on paper and by computer. In the time between participants' visit 2 and visit 4, participants will receive a weekly telephone call to check in with them and remind them to continue taking the study powder. At the very end of the study, when all participants are finished, participants will receive a telephone call to debrief them and notify them which group they were randomized into. An optional tissue banking protocol will be offered for collection of additional blood to be banked at visits 2-4.