Berries, Bugs, and the Blues

This study is an ancillary project to a currently funded randomized, placebo-controlled 12-week intervention in older, sedentary adults with depressive symptoms (IRB# Pro00064749). This specific project proposes distinct aims to the trial by gathering preliminary data on the synergistic impact of dietary fiber and anthocyanins (via freeze-dried blueberry powder) on the gut-microbiota, gut-derived metabolites, and depressive symptoms in older adults.

Participants will then be randomized to consume either 48 g of freeze-dried blueberry powder (~600 mg of anthocyanins and ~8 g of fiber) or 48 g of a nutritionally matched placebo powder (devoid of anthocyanins and fiber) each day for a total of 12 weeks.

At baseline, participants will be undergo assessments for depressive symptom severity and provide a fecal sample for gut microbiota and short chain fatty acid measurement. After 4, 8, and 12 weeks of consuming the powder there will be study visits that assess depressive symptom severity. Additionally, a final fecal sample will be taken after 12 weeks of the intervention.

Inclusion criteria

• Men and women aged ≥65 years
• Self-reporting ≥ 8 hours of sitting per/day (e.g., sedentary behavior)
• Depressive symptoms (defined as ≥4 and <16 points on the center for epidemiological studies depression-scale

Exclusion criteria

• Unwilling to follow the study protocol
• A median daily step count >7,500 steps per day (as measured by the ActiGraph), or per discretion of the PI
• Cognitive impairment (defined as Montreal Cognitive Assessment, MoCA <22 points)
• Self-reporting a history of inflammatory bowel disease/syndrome, major depression, bipolar, schizophrenia, or other psychotic disorders, or per discretion of the PI
• Self-reporting type 1 or type 2 diabetes
• Allergic to intervention or control products
• Recent use (within the last 3 months) of antibiotics, or per discretion of the PI
• Recent use (within the last 3 months) of pro-biotics, or per discretion of the PI
• Current substance use disorder (Drug Abuse Screening Test, DAST-10>2 points)
• Current alcohol use disorder (Alcohol Use Disorders Identification Test - Consumption, AUDIT-C≥4 points)
• Unstable anti-depressant use (e.g., change in medication within last 3-6 months), or per discretion of the PI
• Current homicidal or suicidal ideation (assessed via the P4 Suicidality Screener)
• Current psychosis (via the Psychosis and Hallucinations Questionnaire, PHQ>12 points)
• Manic symptoms (assessed by the Mood Disorder Questionnaire, MDQ >5 points)