Cranberry Polyphenols and Stress Resilience During Multitasking in Healthy Adults (CRAN-MULTI)

Cranberry Polyphenols and Human Stress Resilience: A Randomized, Double-Blind, Placebo-Controlled Clinical Trial Integrating Cognitive, Physiological, and Microbiome Adaptations Underlying Nutritional Neuroprotection and Multitasking Performance in Healthy Adults.

This randomized, double-blind, placebo-controlled clinical trial evaluates whether 70 days of daily cranberry juice consumption improves cognitive performance and motor accuracy and reduces psychological and physiological stress responses during a motor-cognitive dual-task multitasking challenge in healthy adults aged 30-55 (Aim 1). It is hypothesized that chronic cranberry juice intake will enhance dual-task performance and attenuate stress reactivity (Hypothesis 1). It is further hypothesized that cranberry juice will mitigate multitasking-related fatigue, mood fluctuations, and cognitive impairment, accompanied by favorable changes in circulating stress biomarkers and stress-regulatory neurochemical pathways (Aim 2/Hypothesis 2). Finally, the study incorporates gut analysis to determine whether cranberry juice induces beneficial shifts in the gut microbiota and microbial metabolites (e.g., SCFAs) and whether these changes are associated with improved cognitive and stress-related outcomes, consistent with a microbiome-gut-brain axis mechanism (Aim 3/Hypothesis 3).

Study Overview

• Status: Recruiting
• Conditions: Motor Activity; Stress Response; Mental Stress; Physiological Stress; Cognitive Symptoms; Multitasking Behavior and Multitasking Ability
• Intervention / Treatment: Other: Cranberry juice; Other: Placebo juice

Detailed Description

Recruitment and Screening

Individuals who express interest will complete an initial study interest form. If preliminarily qualified, individuals will proceed to a screening process conducted via Qualtrics. Study staff will review responses to confirm eligibility and identify exclusions based on predefined criteria.

Study Design, Visits, and Timeline

This randomized, double-blind, placebo-controlled, parallel-design trial spans 13 weeks and includes three in-person visits: the consent visit (V1), the baseline visit (V2), and the final visit (V3).

Consent Visit (V1)

At V1, participants complete the informed consent process and undergo eligibility checks. These include measurement of height and weight to confirm BMI eligibility, pregnancy testing for female participants to ensure non-pregnant status, and a brief multitasking task capability check to confirm participants can comfortably perform the protocol tasks. Study staff will answer any questions, and V2 and V3 will be scheduled. Upon providing consent, participants enter the run-in phase.

Run-In Phase (Pre-Baseline)

Following V1, participants begin the run-in phase, adhering to the study's dietary restrictions. This includes avoiding cranberry products and specific polyphenol- or supplement-rich foods, as well as limiting caffeine and alcohol near visit days.

Baseline Visit (V2) and Final Visit (V3) Procedures

V2 (baseline) and V3 (final) follow the same structure, with the key difference being the assigned beverage at breakfast during V3.

Pre-Visit Requirements and Intake

Participants arrive after a 10-hour overnight fast. Upon arrival, participants submit a self-collected fecal sample for gut microbiome analysis. Compliance with dietary restrictions is confirmed, after which a phlebotomist draws a fasting blood sample (20 mL). Height and weight are measured.

Core Assessments (V2 and V3)

Multitasking (Dual-Task) Challenge and Stress Reactivity Participants perform a dual-task multitasking paradigm with continuous physiological monitoring. The cognitive task involves counting backward aloud from a random number between 800 and 999, subtracting by 3, 7, and 17 across three series. Each series lasts 4 minutes, with 90-second breaks in between, totaling 15 minutes. Scoring is based on the total correct/incorrect subtractions; if errors occur, participants continue from the new number. The motor task involves clicking rapidly shrinking dots on a screen, scored for target efficiency and accuracy. The multitasking session is video-recorded. Mood and stress are assessed using the State-Trait Anxiety Inventory (STAI-State) and Visual Analog Mood Scales (VAMS) immediately before and after the task. Saliva samples are collected immediately before, immediately after, and 60 minutes after the task to measure cortisol and alpha-amylase.

Standardized Meal (V2 vs. V3)

At V2, participants are served a standardized meal with water. At V3 (Day 70), the standardized meal remains the same, but water is replaced with 8 oz of the assigned beverage (either cranberry juice or placebo).

Cognitive Testing

Following the multitasking challenge and standardized meal, participants complete NIH Toolbox cognition and memory assessments.

Questionnaires and Symptom Monitoring

Participants complete measures assessing mental fatigue, perceived stress, and trait anxiety via Qualtrics.

Post-Visit and Follow-Up

After V2, participants leave with assigned beverages (8 oz per bottle; two bottles per day). V3, the final visit, mirrors V2, except the standardized meal includes 8 oz of the assigned beverage and an additional compliance questionnaire is administered. Participation ends after all final assessments are completed at V3.

• Study Type: Interventional
• Enrollment (Estimated): 84
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Maya E Waintraub, M.S.; Phone Number: 847-246-2255; Email: mwaintraub@ufl.edu

Study Locations

• United States
  • Florida
    • Gainesville, Florida, United States, 32608
      • Recruiting
      • University of Florida
      • Contact: Maya Waintraub, M.S.; Phone Number: 847-246-2255; Email: mwaintraub@ufl.edu
      • Principal Investigator: lewei Gu, PhD

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• At least 110 pounds
• Between 30 and 55 years
• BMI between 18.9 and 29.9 kg/m²
• A minimum education level of high school or above

Exclusion Criteria:

• Heavy caffeine users (consuming more than 300 mg/day or more than two cups of coffee per day)
• Alcohol consumption exceeding three drinks per week
• A smoking history of 10 years or more, or current use of cannabis products
• Uncontrolled hypertension
• Clinically diagnosed illnesses such as diabetes, cardiovascular disease, neurological disorders, or mental health conditions
• Participants currently taking prescribed anti-inflammatory medications, antibiotics, or antidepressants that may affect study outcomes, particularly those related to blood and fecal sample analysis
• Individuals who regularly take vitamin or mineral supplements and are unwilling to discontinue them for the duration of the study will not qualify.
• Participants must be willing to maintain their current daily routine and lifestyle, undergo body weight and height measurements, and notify study coordinators of any illnesses or significant adverse life events during the study period
• Those with specific dietary restrictions that prevent them from consuming the standardized breakfast sandwich required in the study protocol
• Participants must successfully complete the on-site multitasking task as a screening measure prior to signing consent.
• Beck's Depression Inventory score of 21 or higher
• Beck's Anxiety Inventory score of 21 or higher
• A history of severe suicidal tendencies, or seasonal depression
• Pregnancy and breastfeeding (Female participants must complete four pregnancy tests throughout the study and track their menstrual cycle. Those unwilling to comply with these requirements will not be eligible.)
• Potential participants must not have taken any anti-inflammatory medications, antibiotics, or antidepressants within the past three months prior to the start of the study
• Individuals who were previously enrolled in IRB#202300950 will be excluded due to the learning effect of cognitive tests, ensuring accurate data collection for this study

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Triple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Cranberry juice; Cranberry juice will be provided by Ocean Spray Company.	Other: Cranberry juice; Participants will consume the cranberry juice beverage by mouth each day for 70 days following a run-in period.
Placebo Comparator: Placebo cranberry juice; Placebo juice will be provided from Ocean Spray Company to match the appearance, taste, and calories of the cranberry beverage; it contains no active cranberry components.	Other: Placebo juice; Participants will consume the placebo cranberry juice beverage by mouth each day for 70 days following a run-in period.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Cognitive task performance (serial subtraction accuracy)	Total number of correct subtractions during the multitasking cognitive task Measure Description: Counting backward aloud from a random number between 800-999 by 3, 7, and 17; performance scored as total correct subtractions across the task.	Baseline (Visit 2) and Final (Visit 3, Day 70). Through study completion (average of 2 years).
Cognitive task performance (serial subtraction errors)	Outcome Measure: Total number of incorrect subtractions during the multitasking cognitive task Measure Description: Same serial subtraction task; performance scored as total incorrect subtractions.	Baseline (Visit 2) and Final (Visit 3, Day 70). Through study completion (average of 2 years).

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Mood	Change from baseline to end of intervention in mood assessed using the Visual Analog Mood Scale (VAMS). The VAMS is a self-report visual analog measure of current mood states collected during study visits per protocol.	Baseline (Visit 2; pre- and post-multitasking task) and Final (Visit 3, Day 70; pre- and post-multitasking task). Through study completion (average of 2 years).
State anxiety	Change from baseline to end of intervention in state anxiety assessed using the State-Trait Anxiety Inventory - State Subscale (STAI-State). The STAI-State is a self-report measure assessing state anxiety in response to multitasking stress collected during study visits per protocol.	Baseline (Visit 2; pre- and post-multitasking task) and Final (Visit 3, Day 70; pre- and post-multitasking task). Through study completion (average of 2 years).
Mental fatigue	Change from baseline to end of intervention in mental fatigue assessed using the Mental Fatigue Scale (MFS). The MFS is a self-reported questionnaire evaluating perceived mental fatigue and related cognitive symptoms. Scores will be collected during study visits and analyzed per protocol to assess changes following cranberry juice intervention.	Baseline (Visit 2) and Final (Visit 3, Day 70). Through study completion (average of 2 years).
Sleep quality	Change from baseline to end of intervention in sleep quality assessed using the Leeds Sleep Evaluation Questionnaire (LSEQ). The LSEQ is a self-report questionnaire evaluating subjective sleep quality and related dimensions of sleep and awakening, collected during study visits per protocol.	Baseline (Visit 2) and Final (Visit 3, Day 70). Through study completion (average of 2 years).
Trait anxiety	Change from baseline to end of intervention in trait anxiety assessed using the State-Trait Anxiety Inventory - Trait Subscale (STAI-Trait). The STAI-Trait is a self-report measure of trait anxiety.	Baseline (Visit 2) and Final (Visit 3, Day 70). Through study completion (average of 2 years).
Food frequnecy questionnaire	Dietary intake patterns assessed using a Food Frequency Questionnaire (FFQ). The FFQ is a self-report measure used to evaluate habitual dietary intake and food consumption frequency during the run-in phase and throughout the intervention period per protocol.	Run-in (pre-intervention), Baseline (Visit 2), Mid-Intervention, and Day 70 (Visit 3). Through study completion (average of 2 years).
Picture vocabulary test	NIH Toolbox Picture Vocabulary Test: to assess participants' ability to understand and identify the meaning of words by matching them to corresponding images.	Baseline (Visit 2) and Final (Visit 3, Day 70). Through study completion (average of 2 years).
Flanker inhibitory control and attention test	NIH Toolbox Flanker Inhibitory Control and Attention Test: to assess participants' cognitive control and attentional processes, specifically their ability to inhibit irrelevant information and focus on the relevant stimuli.	Baseline (Visit 2) and Final (Visit 3, Day 70). Through study completion (average of 2 years).
List sorting working memory test	NIH Toolbox List Sorting Working Memory Test: to assess participants' working memory abilities.	Baseline (Visit 2) and Final (Visit 3, Day 70). Through study completion (average of 2 years).
Dimensional changes card sort test	NIH Toolbox Dimensional Changes Card Sort Test: to assess the cognitive flexibility of participants.	Baseline (Visit 2) and Final (Visit 3, Day 70). Through study completion (average of 2 years).
Pattern comparison processing speed test	NIH Toolbox Pattern Comparison Processing Speed Test: to assess the cognitive processing speed of participants.	Baseline (Visit 2) and Final (Visit 3, Day 70). Through study completion (average of 2 years).
Picture sequence memory test	NIH Toolbox Picture Sequence Memory Test: to assess participants' episodic memory.	Time Frame: Baseline (Visit 2) and Final (Visit 3, Day 70). Through study completion (average of 2 years).
Auditory verbal learning test	Auditory Verbal Learning Test: to assess participants' attention, memory, and learning ability in the auditory-verbal domain.	Baseline (Visit 2) and Final (Visit 3, Day 70). Through study completion (average of 2 years).
Picture sequence memory test	NIH Toolbox Picture Sequence Memory Test: to assess participants' episodic memory.	Baseline (Visit 2) and Final (Visit 3, Day 70). Through study completion (average of 2 years).
Heart rate	Heart rate (bpm) will be measured during multitasking.	Baseline (Visit 2) and Final (Visit 3, Day 70). Through study completion (average of 2 years).
Interbeat interval (IBI)	Interbeat interval (ms) will be measured during multitasking.	Baseline (Visit 2) and Final (Visit 3, Day 70). Through study completion (average of 2 years).
Galvanic skin response (GSR)	Galvanic skin response (μS) will be measured during multitasking.	Baseline (Visit 2) and Final (Visit 3, Day 70). Through study completion (average of 2 years).
Salivary alpha-amylase activity	Salivary alpha-amylase activity will be assessed using ELISA kit.	Baseline (Visit 2) and Final (Visit 3, Day 70). Through study completion (average of 2 years).
Salivary cortisol level	Salivary cortisol level will be measured by an enzyme immunoassay with the Cortisol Elisa Assay Kit.	Baseline (Visit 2) and Final (Visit 3, Day 70). Through study completion (average of 2 years).

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Gut microbiome composition and diversity	Change from baseline to end of intervention in gut microbiome composition and diversity assessed from stool samples.	Baseline (Visit 2) and Final (Visit 3, Day 70). Through study completion (average of 2 years).
Short-chain fatty acids (SCFAs)	Change from baseline to end of intervention in fecal concentrations of acetic acid, propionic acid, and butyric acid assessed from stool samples.	Baseline (Visit 2) and Final (Visit 3, Day 70). Through study completion (average of 2 years).

Collaborators and Investigators

• Sponsor: University of Florida
• Investigators: Principal Investigator: Lewei Gu, PhD, University of Florida

Study record dates

Study Major Dates

• Study Start (Estimated): April 1, 2026
• Primary Completion (Estimated): May 1, 2028
• Study Completion (Estimated): August 1, 2029

Study Registration Dates

• First Submitted: January 26, 2026
• First Submitted That Met QC Criteria: March 2, 2026
• First Posted (Actual): March 6, 2026

Study Record Updates

• Last Update Posted (Actual): March 6, 2026
• Last Update Submitted That Met QC Criteria: March 2, 2026
• Last Verified: January 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Neurologic Manifestations; Nervous System Diseases; Wounds and Injuries; Behavioral Symptoms; Fractures, Bone; Pathological Conditions, Signs and Symptoms; Behavior; Signs and Symptoms; Neurobehavioral Manifestations; Stress, Psychological; Fractures, Stress; Motor Activity; Multitasking Behavior
• Other Study ID Numbers: IRB 202500138

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No