AgingNCT06942351
Effect of Walnuts on Cognitive Function and Gut Microbiome in Older Adults
A study testing Walnuts and Crackers in people with Aging and Inflammation Biomarkers, run by Oregon State University at 1 site in United States.
Trial 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. Read more about this study
- Who is it for?
- Ages 55 years and olderHealthy volunteers can take part
- Conditions the study is for
- Aging, Inflammation Biomarkers
- What is being tested?
- Walnuts and Crackers
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 90 participants
- Where
- 1 siteUnited States
- Study dates
- 9 Jun 2025to May 2029
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 55 years and older
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- 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
Show all 11Show fewer
- 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)
Who cannot join
- 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
Show all 28Show fewer
- Diagnosis of sickle cell disease
- Susceptibility to motion sickness
- Consumes 3 or more alcoholic drinks daily
- History of smoking tobacco products, including e-cigarettes and vaporizers in the past 2 years (smokeless tobacco use not exclusionary)
- 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 cancer in the past 5 years (Skin cancer that was only surgically treated is not exclusionary)
- 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
- History of chronic bronchitis or emphysema
- Diagnosis of dementia or Alzheimer's disease
- History of head injury requiring hospitalization or loss of consciousness > 5 minutes
- History of chronic migraines (for at least 3 months, headache occurring on 15 or more days per month, where at least 8 of those headache days have migraine symptoms)
- Blood pressure above 159 (systolic) or 99 (diastolic) mm Hg
- Corrected vision worse than 20/50
- Score of less than 10/15 on Ishihara color vision test or diagnosis of color blindness
- Score of less than 26/30 on Mini-Mental State Exam
- Score of greater than 15 on Center for Epidemiologic Depression survey
- History of disease or disorder which causes cognitive impairment, including but limited to: attention-deficit/hyperactivity disorder (ADHD), amyotrophic lateral sclerosis, autism, bipolar disorder, Down's syndrome, encephalitis, epilepsy/seizures, human immunodeficiency virus (HIV), Huntington's disease, Korsakoff's psychosis, multiple sclerosis, Parkinson's disease, or psychotic disorders (e.g., schizophrenia, schizoaffective disorder, schizophreniform disorder)
- Current and regular use of any of the following medications: insulin, opioids, anti-seizure medications, psychotropic medications: stimulants, anti-psychotics, or medications that cause daytime drowsiness or difficulty concentrating
Trial locations and contacts
1 site in 1 country.
About this study
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.
Read the detailed description
The investigators will determine the extent to which daily consumption of walnuts by older adults for 12 weeks influences cognitive function and whether improvements are associated with changes in the resident gut microbiota. The investigators propose that age-related cognitive decline can be mitigated by consuming walnuts, by modulating the microbiota and microbial metabolites and decreasing oxidative stress and inflammation.
- Conditions
- Aging, Inflammation Biomarkers
- Being tested
- Walnuts, Crackers
- Keywords
- gut microbiome, walnuts, cognitive function
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
WalnutsOther
Daily consumption of 1.5 ounces of plain walnuts for 12 weeks
CrackersOther
Daily consumption of non-whole grain crackers for 12 weeks (caloric equivalent to 1.5 ounces of plain walnuts)
| Study group | Role | What they receive |
|---|---|---|
| Walnuts | Active comparator | Daily consumption of 1.5 ounces (42.5 g) of plain walnuts for 12 weeks Receives: Other: Walnuts |
| Crackers | Placebo comparator | Daily consumption of non-whole grain crackers for 12 weeks (caloric equivalent to 1.5 ounces of plain walnuts) Receives: Other: Crackers |
What is being measured
The primary outcome is the main question the study is designed to answer.
Cognitive function - memory, age adjusted
Change from baseline at week 12: age adjusted standard scores (higher score reflects positive outcome)
Measured: 0 and 12 weeks
Cognitive function - memory, proximity
Change from baseline at week 12: proximity (lower score reflects positive outcome)
Measured: 0 and 12 weeks
Cognitive function - cognitive flexibility, age adjusted
Change from baseline at week 12: age adjusted standard scores (higher score reflects positive outcome)
Measured: 0 and 12 weeks
Cognitive function - cognitive flexibility, proximity
Change from baseline at week 12: proximity (lower score reflects positive outcome)
Measured: 0 and 12 weeks
Cognitive function - speed of processing
Change from baseline at week 12: age adjusted standard scores (higher score reflects positive outcome)
Measured: 0 and 12 weeks
Gut microbiome composition
Change from baseline at week 12: microbiome composition
Measured: 0 and 12 weeks
Lipid oxidation levels
Change from baseline at week 12: plasma malondialdehyde (MDA)
Measured: 0 and 12 weeks
Gut permeability and health: Inflammatory biomarkers
Change from baseline at week 12: Gut inflammatory biomarkers fecal calprotectin and myeloperoxidase
Measured: 0 and 12 weeks
Biomarkers of inflammation
Change from baseline at week 12: Plasma inflammatory markers (ex. CRP and IL-6)
Measured: 0 and 12 weeks
Secondary outcomes (3)
Urolithin concentrations
Change from baseline at week 12: urolithin A and urolithin B concentrations in urine
Measured: 0 and 12 weeks
Blood pressure
Change from baseline at week 12: systolic and diastolic blood pressure
Measured: 0 and 12 weeks
Weight
Change from baseline at week 12: weight
Measured: 0 and 12 weeks
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted24 Apr 2025
- Study start9 Jun 2025
- Primary completionDec 2028 (estimated)
- Study completionMay 2029 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for AgingStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind
- Who is masked
- Outcomes assessor
- Enrolment
- 90 participants (actual)
Sponsor and investigators
- Lead sponsor
- Oregon State University
- Sponsor type
- University, hospital or other
- Collaborators
- California Walnut Commission
- Responsible party
- Principal investigator, Emily Ho, Oregon State University
- Investigators
- Emily Ho, PhD, Principal investigator, Oregon State University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06942351
- Sponsor's protocol ID
- LPI-1153
- Status last verified
- Aug 2026
- First submitted
- 8 Apr 2025
- Last updated
- 7 Aug 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: Individual participant data will not be shared with other researchers without IRB approval.
Study at a glance
From the registry record, last updated by the sponsor on 7 Aug 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Effect of Walnuts on Cognitive Function and Gut Microbiome in Older Adults
- ClinicalTrials.gov ID
- NCT06942351
- Acronym / sponsor ID
- LPI-1153
- Conditions
- Aging, Inflammation Biomarkers
- Keywords
- gut microbiome, walnuts, cognitive function
- Study type
- Interventional
- Recruitment status
- Active, not recruiting
- Enrolment
- 90 participants (actual)
- Lead sponsor
- Oregon State UniversityUniversity, hospital or other
- Collaborators
- California Walnut Commission
- Study start
- 9 Jun 2025 (actual)
- Primary completion
- Dec 2028 (estimated)
- Study completion
- May 2029 (estimated)
- First posted
- 24 Apr 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
Detailed description
The investigators will determine the extent to which daily consumption of walnuts by older adults for 12 weeks influences cognitive function and whether improvements are associated with changes in the resident gut microbiota. The investigators propose that age-related cognitive decline can be mitigated by consuming walnuts, by modulating the microbiota and microbial metabolites and decreasing oxidative stress and inflammation.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind (outcomes assessor)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Walnuts | Active comparator | Other: WalnutsDaily consumption of 1.5 ounces (42.5 g) of plain walnuts for 12 weeks |
| Crackers | Placebo comparator | Other: CrackersDaily consumption of non-whole grain crackers for 12 weeks (caloric equivalent to 1.5 ounces of plain walnuts) |
Who may qualify
- Ages
- 55 years and older
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (11 listed)
- 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
Key exclusion criteria (28 listed)
- 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
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| WalnutsDaily consumption of 1.5 ounces of plain walnuts for 12 weeks | Other | Walnuts |
| CrackersDaily consumption of non-whole grain crackers for 12 weeks (caloric equivalent to 1.5 ounces of plain walnuts) | Other | Crackers |
Primary outcome
Cognitive function - memory, age adjusted
Time frame: 0 and 12 weeks
Change from baseline at week 12: age adjusted standard scores (higher score reflects positive outcome)
Cognitive function - memory, proximity
Time frame: 0 and 12 weeks
Change from baseline at week 12: proximity (lower score reflects positive outcome)
Cognitive function - cognitive flexibility, age adjusted
Time frame: 0 and 12 weeks
Change from baseline at week 12: age adjusted standard scores (higher score reflects positive outcome)
Cognitive function - cognitive flexibility, proximity
Time frame: 0 and 12 weeks
Change from baseline at week 12: proximity (lower score reflects positive outcome)
Cognitive function - speed of processing
Time frame: 0 and 12 weeks
Change from baseline at week 12: age adjusted standard scores (higher score reflects positive outcome)
Gut microbiome composition
Time frame: 0 and 12 weeks
Change from baseline at week 12: microbiome composition
Lipid oxidation levels
Time frame: 0 and 12 weeks
Change from baseline at week 12: plasma malondialdehyde (MDA)
Gut permeability and health: Inflammatory biomarkers
Time frame: 0 and 12 weeks
Change from baseline at week 12: Gut inflammatory biomarkers fecal calprotectin and myeloperoxidase
Biomarkers of inflammation
Time frame: 0 and 12 weeks
Change from baseline at week 12: Plasma inflammatory markers (ex. CRP and IL-6)
3 secondary outcomes
Urolithin concentrations
Time frame: 0 and 12 weeks
Blood pressure
Time frame: 0 and 12 weeks
Weight
Time frame: 0 and 12 weeks
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 7 Aug 2026.
- 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.Link provided by the sponsor.
- Individual participant dataSharing planned: No. Individual participant data will not be shared with other researchers without IRB approval.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Emily Ho, PhD principal investigator
Oregon State University
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Walnuts and Crackers in people with Aging and Inflammation Biomarkers, run by Oregon State University at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 11 inclusion and 28 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: under way, not looking for participants, as of the sponsor's last update on 7 Aug 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Cognitive function - memory, age adjusted (time frame: 0 and 12 weeks). The study lists 9 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 7 Aug 2026.