Long-COVIDNCT07429903
Effect of Daily Walnut Consumption on Memory in Subjects With Long-COVID
A study testing whole food - walnuts in people with Long-COVID and Brain Fog, run by University of California, Los Angeles at 1 site in United States.
Trial summary
Approximately 30% of patients experience "Long-COVID" syndrome presenting with symptoms such as cognitive difficulties ('brain fog'), fatigue, dyspnea, autonomic dysfunction, depression and anxiety, lasting beyond 12 weeks causing significant disability, and threaten health and wellbeing of millions around the world. Read more about this study
- Who is it for?
- Ages 40 years and older
- Conditions the study is for
- Long-COVID, Brain Fog, Cognition
- What is being tested?
- whole food - walnuts
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 31 participants
- Where
- 1 siteUnited States
- Study dates
- 21 Sep 2023to 24 Jan 2025
- Phase
- Interventional
- Are there results?
- None posted in the registry
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 40 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Age 40 years and older
- History of confirmed SARS-CoV-2 infection
- Presence of long-COVID symptoms lasting longer than 12 weeks, including one or more of the following:
- Cognitive complaints ("brain fog," memory, attention, or processing speed difficulties)
- Fatigue
- Mood symptoms (e.g., depression)
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- Consumption of a low-polyphenol (Western) diet
- Adequate visual acuity and hearing to complete neuropsychological testing
- Screening laboratory results without clinically significant abnormalities that would interfere with study participation
- Ability and willingness to provide written informed consent
Who cannot join
- Diagnosis of probable Alzheimer's disease or other dementia (e.g., vascular, Lewy body, frontotemporal)
- Other neurological or medical conditions that may cause cognitive impairment
- Evidence of Parkinson's disease based on motor examination
- Uncontrolled hypertension (systolic BP >170 mmHg or diastolic BP >100 mmHg)
- Allergy to walnuts
- Regular consumption of more than 5 oz of walnuts per week
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- Current diagnosis of a major psychiatric disorder according to DSM-5 criteria
- Alcoholism or substance use disorder
- Any condition that, in the investigator's judgment, would make participation unsafe or interfere with study completion
Trial locations and contacts
1 site in 1 country.
United States1 site
UCLA Center for Human Nutrition
Los Angeles, California, 90025
About this study
Approximately 30% of patients experience "Long-COVID" syndrome presenting with symptoms such as cognitive difficulties ('brain fog'), fatigue, dyspnea, autonomic dysfunction, depression and anxiety, lasting beyond 12 weeks causing significant disability, and threaten health and wellbeing of millions around the world. At the current time, there is no effective treatment for long-COVID. Walnuts contain a mixture of nutrients and phytochemicals include monounsaturated fatty acids (MUFA), polyunsaturated fatty acids (PUFA), and alpha-linolenic acid (ALA). Walnut consumption was directly associated with cognitive function. The investigators have shown pomegranate that share the same phytonutrient ellagitannins as walnut and mixed nuts including walnuts could increase blood microbiome metabolites of tryptophan metabolite indole propionate and serotonin levels via change of gut microbiota and therefore play an essential role in gut-brain axis including cognitive function. The proposed pilot study will include 76 adults (ages >40 years) with diagnosis of SARS-CoV2 infection presenting with long-COVID symptoms lasting longer than 12 weeks. They will be randomized 1:1 to usual care vs. an intervention group that will include 2 oz (57g) of walnuts daily into their habitual diet for 12 weeks. The investigators will compare the improvement in symptoms of cognitive complains of "brain fog", fatigue and depression of the active intervention group vs. usual care. The outcome of the investigation of the benefit of walnut consumption will provide important novel information on using dietary sources of polyunsaturated fatty acids and phytochemicals to mitigate the common symptoms of long-COVID. This application was submitted in response to the California Walnut Commission's commodity board topic.
- Conditions
- Long-COVID, Brain Fog, Cognition, Memory
- Being tested
- whole food - walnuts
- Medical subject headings
- Post-Acute COVID-19 Syndrome, Mental Fatigue
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
whole food - walnutsOther
Participants randomized to the intervention group will consume (2 oz ) of whole walnuts daily, incorporated into their diet for 12 weeks. Walnuts were provided to participants, and adherence was monitored using dietary records.
| Study group | Role | What they receive |
|---|---|---|
| Walnuts | Experimental | Not described Receives: Other: whole food - walnuts |
| Control | No intervention | Habitual diet while avoiding nuts |
What is being measured
The primary outcome is the main question the study is designed to answer.
Episodic Memory - RAVLT-Revised Long-Delay Free Recall (number of words recalled)
Change in long-delay free recall score (number of words correctly recalled) on the RAVLT-Revised from baseline to week 12.
Measured: Baseline to Week 12
Secondary outcomes (12)
Executive Function
Digit Vigilance Test Score Description: Total completion time (seconds) and/or number of errors on the Digit Vigilance Test, assessing sustained attention and processing speed.
Measured: Baseline to Week 12
Trail Making Test Part A Completion Time
Description: Time to completion (seconds) for Trail Making Test Part A, assessing processing speed.
Measured: baseline and 12 weeks
Fatigue
Patient-Reported Outcomes Measurement Information System (PROMIS®) Fatigue Short Form - 8 Item.
Fatigue will be assessed using the Patient-Reported Outcomes Measurement Information System (PROMIS®) Fatigue Short Form (8 items). Raw scores range from 8 to 40, with higher scores indicating greater fatigue (worse outcome). Scores may also be converted to standardized T-scores (mean = 50, SD = 10), where higher T-scores indicate greater fatigue.
Measured: Baseline and 12
Mood
PROMIS® Depression Short Form (8 items)
Measured: baseline and 12 weeks
NIH Toolbox Cognitive Battery (NIHTB-CB) - Fluid Intelligence Composite
Fluid cognitive function will be assessed using the Fluid Intelligence Composite score from the NIH Toolbox Cognitive Battery. The composite is a standardized score (mean = 100, SD = 15), with higher scores indicating better cognitive performance.
Measured: Baseline to Week 12
Quality of Life
SF-36 Health Survey
Measured: Baseline and 12
Blood Pressure
Seated systolic and diastolic blood pressure
Systolic and diastolic blood pressure will be measured in millimeters of mercury (mmHg) using an automated calibrated sphygmomanometer after 5 minutes of seated rest. Higher values indicate higher blood pressure.
Measured: Baseline and Week 12
Dietary Intake
24-hour dietary recall (ASA24™)
Measured: Baseline and 12
Blood and Urine Biomarkers
Measures:
metabolic markers and inflammatory Blood fatty acid profile Plasma ellagic acid Urinary urolithin metabolites (LC-MS/MS)
Measured: Baseline, 12 Weeks
WAIS-IV Symbol Search Score
Total correct responses (scaled score) on the WAIS-IV Symbol Search subtest, assessing processing speed.
Measured: Baseline and 12 weeks
Heart Rate
Resting heart rate
Description:
Resting heart rate will be measured in beats per minute (bpm) using an automated blood pressure monitor after 5 minutes of seated rest.
Measured: Baseline and Week 12
Body Weight
Measure:
Body weight in kilograms
Description:
Body weight will be measured in kilograms (kg) using a calibrated digital scale with participants wearing light clothing and no shoes.
Measured: baseline and week 12
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted24 Feb 2026
- Study start21 Sep 2023
- Primary completion24 Jan 2025
- Study completion24 Jan 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Long-COVIDStudies of the same condition, open and under way.
- More trials run by University of California, Los AngelesThe sponsor's other registered studies.
- 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
- Supportive care
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind
- Who is masked
- Outcomes assessor
- Enrolment
- 31 participants (actual)
Sponsor and investigators
- Lead sponsor
- University of California, Los Angeles
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Zhaoping Li, University of California, Los Angeles
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07429903
- Sponsor's protocol ID
- 23-000654
- Status last verified
- Jan 2026
- First submitted
- 23 Jan 2026
- Last updated
- 24 Feb 2026
- Results posted
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 24 Feb 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Effect of Daily Walnut Consumption on Memory in Subjects With Long-COVID
- ClinicalTrials.gov ID
- NCT07429903
- Acronym / sponsor ID
- 23-000654
- Conditions
- Long-COVID, Brain Fog, Cognition, Memory
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 31 participants (actual)
- Lead sponsor
- University of California, Los AngelesUniversity, hospital or other
- Study start
- 21 Sep 2023 (actual)
- Primary completion
- 24 Jan 2025 (actual)
- Study completion
- 24 Jan 2025 (actual)
- First posted
- 24 Feb 2026 (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.
Approximately 30% of patients experience "Long-COVID" syndrome presenting with symptoms such as cognitive difficulties ('brain fog'), fatigue, dyspnea, autonomic dysfunction, depression and anxiety, lasting beyond 12 weeks causing significant disability, and threaten health and wellbeing of millions around the world. At the current time, there is no effective treatment for long-COVID. Walnuts contain a mixture of nutrients and phytochemicals include monounsaturated fatty acids (MUFA), polyunsaturated fatty acids (PUFA), and alpha-linolenic acid (ALA). Walnut consumption was directly associated with cognitive function. The investigators have shown pomegranate that share the same phytonutrient ellagitannins as walnut and mixed nuts including walnuts could increase blood microbiome metabolites of tryptophan metabolite indole propionate and serotonin levels via change of gut microbiota and therefore play an essential role in gut-brain axis including cognitive function. The proposed pilot study will include 76 adults (ages >40 years) with diagnosis of SARS-CoV2 infection presenting with long-COVID symptoms lasting longer than 12 weeks. They will be randomized 1:1 to usual care vs. an intervention group that will include 2 oz (57g) of walnuts daily into their habitual diet for 12 weeks. The investigators will compare the improvement in symptoms of cognitive complains of "brain fog", fatigue and depression of the active intervention group vs. usual care. The outcome of the investigation of the benefit of walnut consumption will provide important novel information on using dietary sources of polyunsaturated fatty acids and phytochemicals to mitigate the common symptoms of long-COVID. This application was submitted in response to the California Walnut Commission's commodity board topic.
Study design
- Primary purpose
- Supportive care
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind (outcomes assessor)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Walnuts | Experimental | Other: whole food - walnuts |
| Control | No intervention | –Habitual diet while avoiding nuts |
Who may qualify
- Ages
- 40 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (10 listed)
- Age 40 years and older
- History of confirmed SARS-CoV-2 infection
- Presence of long-COVID symptoms lasting longer than 12 weeks, including one or more of the following:
- Cognitive complaints ("brain fog," memory, attention, or processing speed difficulties)
- Fatigue
Key exclusion criteria (9 listed)
- Diagnosis of probable Alzheimer's disease or other dementia (e.g., vascular, Lewy body, frontotemporal)
- Other neurological or medical conditions that may cause cognitive impairment
- Evidence of Parkinson's disease based on motor examination
- Uncontrolled hypertension (systolic BP >170 mmHg or diastolic BP >100 mmHg)
- Allergy to walnuts
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 |
|---|---|---|
| whole food - walnutsParticipants randomized to the intervention group will consume (2 oz ) of whole walnuts daily, incorporated into their diet for 12 weeks. Walnuts were provided to participants, and adherence was monitored using dietary records. | Other | Walnuts |
Primary outcome
Episodic Memory - RAVLT-Revised Long-Delay Free Recall (number of words recalled)
Time frame: Baseline to Week 12
Change in long-delay free recall score (number of words correctly recalled) on the RAVLT-Revised from baseline to week 12.
12 secondary outcomes
Executive Function
Time frame: Baseline to Week 12
Trail Making Test Part A Completion Time
Time frame: baseline and 12 weeks
Fatigue
Time frame: Baseline and 12
Mood
Time frame: baseline and 12 weeks
NIH Toolbox Cognitive Battery (NIHTB-CB) - Fluid Intelligence Composite
Time frame: Baseline to Week 12
Quality of Life
Time frame: Baseline and 12
Blood Pressure
Time frame: Baseline and Week 12
Dietary Intake
Time frame: Baseline and 12
Blood and Urine Biomarkers
Time frame: Baseline, 12 Weeks
WAIS-IV Symbol Search Score
Time frame: Baseline and 12 weeks
Heart Rate
Time frame: Baseline and Week 12
Body Weight
Time frame: baseline and week 12
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 24 Feb 2026.
- Individual participant dataSharing planned: No
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Epigenetic Changes in Long COVID Patients
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Dapagliflozin for Long COVID Syndrome
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Long COVID Brain Fog: Cognitive Rehabilitation Trial
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RecruitingPhase 2
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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.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing whole food - walnuts in people with Long-COVID and Brain Fog, run by University of California, Los Angeles 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 10 inclusion and 9 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: finished, as of the sponsor's last update on 24 Feb 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. 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?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
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?
Episodic Memory - RAVLT-Revised Long-Delay Free Recall (number of words recalled) (time frame: Baseline to Week 12). 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 24 Feb 2026; AzTrials last refreshed its copy on 6 Nov 2026.