Cognition, Flavonoids, Exercise, Gut Microbiome

Inclusion Criteria: * Score on the Montreal Cognitive Assessment (MoCA test) of 24.1-25.2 that indicates mild cognitive decline. The MoCA test score ranges from 0 to 30, with higher scores from 26 to 30 considered normal. * Healthy, non-smoking male or female participants 65 to 85 years of age. * Capable of engaging in a supervised 12-week exercise training program (brisk walking or stretching). * Physically inactive (defined as less than 150 min/week moderate or less than 75 minutes vigorous aerobic and/or resistance exercise during the past 4 weeks). * Willingness to be randomized to one of four groups. * Willingness to provide blood, urine, and fecal samples (3 each), * Willingness to avoid blueberry intake during the 12-weeks study (other than what is provided through the study). * Willingness to maintain current diet and physical activity patterns during the study (other than what is prescribed as a part of the study), and make no formal attempts to lose or gain body weight. * Willingness to be a participant in this study only and not enter any other studies. Exclusion Criteria: * Allergy to blueberries. * Diagnosis of Type I or Type 2 diabetes. * Chronic cardiovascular, metabolic, or renal condition that is uncontrolled (controlled defined as stable for 6 months or more). * History of signs or symptoms during rest or physical activity such as chest discomfort, unreasonable breathlessness, dizziness, fainting, or blackouts. * Use of any prescription or over-the-counter drug intended to support cognition or with known cognitive side effects. * Any other concurrent condition or use of medications or supplements which, in the opinion of the study clinician would preclude participation in this study. * Diagnosis of dementia.