Actively Recruiting
Effect of Walnuts on Cognitive Function and Gut Microbiome in Older Adults
Led by Oregon State University · Updated on 2025-06-19
80
Participants Needed
1
Research Sites
21 weeks
Total Duration
On this page
Sponsors
O
Oregon State University
Lead Sponsor
C
California Walnut Commission
Collaborating Sponsor
AI-Summary
What this Trial Is About
Researchers are evaluating how daily walnut consumption over 12 weeks affects cognitive function, inflammation markers, oxidative stress, and the gut microbiome in healthy adults aged 55 and older. The study aims to see if walnuts can help reduce age-related cognitive decline by changing gut bacteria and lowering inflammation and oxidative damage. Participants are randomly assigned to one of two groups: one consumes 1.5 ounces (42.5 g) of plain walnuts daily for 12 weeks, while the other consumes a caloric equivalent of non-whole grain crackers for the same period. The study is single-blinded, meaning participants do not know which group they are in. During the study, participants will complete cognitive tests measuring memory, cognitive flexibility, and processing speed at the start and after 12 weeks. Researchers will also analyze gut microbiome composition, lipid oxidation, inflammatory biomarkers, and blood pressure. Additional measures include urolithin concentrations and weight. Participants must follow dietary restrictions and attend scheduled assessments throughout the 12-week study.
CONDITIONS
Brief Title
Effect of Walnuts on Cognitive Function and Gut Microbiome in Older Adults
Who Can Participate
Eligibility Criteria
You may qualify if you...
- 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 allowed)
- Able to write legibly and use a computer joystick with at least one hand
- Able to speak, read, and understand English
- Score greater than 79 on water maze learning task
- Willing to maintain current eating patterns
- Willing and able to complete cognitive tests
- Willing to stop consuming certain nuts, berries, and probiotic supplements during study period
- Willing to limit intake of certain wines, spirits, and berries and remain consistent with coffee, tea, and fruit intake
You will not qualify if you...
- Consumed more than 2 oz combined of walnuts, pecans, and chestnuts per week in past 3 months
- Used oral antibiotics in past month
- Regular use of oral anti-inflammatory medications in past month
- Allergy or intolerance to nuts, wheat, or gluten
- Pregnant or planning pregnancy during study
- Weighs less than 110 pounds
- Diagnosis of sickle cell disease
- Susceptible to motion sickness
- Consumes 3 or more alcoholic drinks daily
- History of tobacco smoking in past 2 years
- Use of psilocybin or cannabis products in past 2 years
- Current treatment for alcohol or substance use disorder
- History of heart attack, heart failure, stroke, or transient ischemic attack
- History of liver or kidney disease requiring dialysis
- Cancer history in past 5 years (except surgically treated skin cancer)
- History of bariatric surgery or certain digestive disorders
- Untreated thyroid disorder
- History of chronic bronchitis or emphysema
- Diagnosis of dementia or Alzheimer's disease
- History of head injury with hospitalization or loss of consciousness over 5 minutes
- History of chronic migraines
- Blood pressure above 159/99 mm Hg
- Corrected vision worse than 20/50
- Color blindness or score less than 10/15 on color vision test
- Score less than 26/30 on Mini-Mental State Exam
- Score greater than 15 on depression survey
- History of diseases causing cognitive impairment
- Current regular use of insulin, opioids, anti-seizure, or psychotropic medications
AI-Screening
AI-Powered Screening
Complete this quick 3-step screening to check your eligibility
Your Study Journey
Duration - 2 to 4 weeks
Participants are screened for eligibility to participate in the trial.
1 visit (in-person)
Duration - 12 weeks
Participants consume either 1.5 ounces of plain walnuts or non-whole grain crackers daily for 12 weeks to assess effects on cognitive function and gut microbiome.
Regular visits at the start and end of the treatment period
Trial Site Locations
Total: 1 location
1
Oregon State University
Corvallis, Oregon, United States, 97331
Actively Recruiting
Research Team
E
Emily Ho, PhD
S
Sandra Uesugi, RN, BSN, MS
How is the study designed?
Study Type
INTERVENTIONAL
Masking
SINGLE
Allocation
RANDOMIZED
Model
PARALLEL
Primary Purpose
BASIC_SCIENCE
Number of Arms
2
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