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

NCT06942351 | Recruiting

• 1 other identifier: LPI-1153
• Study Type: interventional
• Target: 80
• Locations: 1 country
• Sites: 1

Brief Summary

The purpose of this study is to examine the impact of daily consumption of walnuts for 12 weeks on cognitive function, markers of inflammation and oxidative stress, and the gut microbiome in healthy adults age 55 years and older.

Conditions

Aging; Inflammation Biomarkers

Keywords

gut microbiome; walnuts; cognitive function

Outcome Measures

Primary Outcomes (9)

• Cognitive function - memory

  Change from baseline at week 12: age adjusted standard scores (higher score reflects positive outcome)

  0 and 12 weeks

• Cognitive function - memory

  Change from baseline at week 12: proximity (lower score reflects positive outcome)

  0 and 12 weeks

• Cognitive function - cognitive flexibility

  Change from baseline at week 12: age adjusted standard scores (higher score reflects positive outcome)

  0 and 12 weeks

• Cognitive function - cognitive flexibility

  Change from baseline at week 12: proximity (lower score reflects positive outcome)

  0 and 12 weeks

• Cognitive function - speed of processing

  Change from baseline at week 12: age adjusted standard scores (higher score reflects positive outcome)

  0 and 12 weeks

• Gut microbiome composition

  Change from baseline at week 12: microbiome composition

  0 and 12 weeks

• Lipid oxidation levels

  Change from baseline at week 12: plasma malondialdehyde (MDA)

  0 and 12 weeks

• Gut permeability and health: Inflammatory biomarkers

  Change from baseline at week 12: Gut inflammatory biomarkers fecal calprotectin and myeloperoxidase

  0 and 12 weeks

• Biomarkers of inflammation

  Change from baseline at week 12: Plasma inflammatory markers (ex. CRP and IL-6)

  0 and 12 weeks

Secondary Outcomes (3)

• Urolithin concentrations

  0 and 12 weeks

• Blood pressure

  0 and 12 weeks

• Weight

  0 and 12 weeks

Study Arms (2)

Walnuts

ACTIVE COMPARATOR

Daily consumption of 1.5 ounces (42.5 g) of plain walnuts for 12 weeks

Other: Walnuts

Crackers

PLACEBO COMPARATOR

Daily consumption of non-whole grain crackers for 12 weeks (caloric equivalent to 1.5 ounces of plain walnuts)

Other: Crackers

Interventions

Walnuts OTHER

Daily consumption of 1.5 ounces of plain walnuts for 12 weeks

Walnuts

Crackers OTHER

Daily consumption of non-whole grain crackers for 12 weeks (caloric equivalent to 1.5 ounces of plain walnuts)

Crackers

Eligibility Criteria

• Age: 55 Years+
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• 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 study (14 weeks)

You may not qualify if:

• Consumption of walnuts, pecans, and chestnuts combined greater than 2 oz / week in the past 3 months.
• Use of oral antibiotics in the past month
• Regular use of oral anti-inflammatory medications in the past month
• Nut, wheat, or gluten allergy/intolerance
• Pregnant or planning to become pregnant during the study period
• Weighs less than 110 pounds
• Diagnosis of sickle cell disease
• Susceptibility to motion sickness
• Consumes 3 or more alcoholic drinks daily
• Use of psilocybin or cannabis products (including CBD-only products) in the past 2 years
• Current treatment for alcohol or other substance use disorder
• History of heart attack, heart failure, or stroke, including transient ischemic attack
• History of liver disease or kidney disease requiring dialysis
• History of bariatric surgery (e.g., gastric bypass, gastric banding, sleeve gastrectomy, etc.) or disorders (e.g., Crohn's disease, unmanaged celiac disease, ulcerative colitis)
• History of thyroid disorder that requires medication, but subject is not taking medication

Sponsors & Collaborators

• Oregon State University: lead
• California Walnut Commission: collaborator

Study Sites (1)

Oregon State University

Corvallis, Oregon, 97331, United States

RECRUITING

Related Links

• This website provides detailed study information for potential participants as well as an online screening survey to assess potential eligibility. Additionally, 2 in-person screening visits follow the online screening survey to assess eligibility.

Study Officials

• Emily Ho, PhD

  Oregon State University

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Emily Ho, PhD

CONTACT

541-737-9559; emily.ho@oregonstate.edu

Sandra Uesugi, RN, BSN, MS

CONTACT

541-737-3594; sandra.uesugi@oregonstate.edu

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: OUTCOMES ASSESSOR
• Masking Details: Study staff performing cognitive tests and analyzing samples and cognitive data will be blinded.
• Purpose: BASIC SCIENCE
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Endowed Chair and Director, Linus Pauling Institute University Distinguished Professor, College of Health

Study Record Dates

• First Submitted: April 8, 2025
• First Posted: April 24, 2025
• Study Start: June 9, 2025
• Primary Completion (Estimated): December 1, 2028
• Study Completion (Estimated): May 1, 2029
• Last Updated: June 19, 2025

Record last verified: 2025-04

Data Sharing

• IPD Sharing: Will not share

Locations

US (1)