Effects of New Zealand Blackcurrant Supplementation on Exercise and Cognitive Performance in Resistance-Trained Adults

NCT07619976 | Completed

• 2 other identifiers: JSU-EPNL-2026-02IRB #12132022-01
• Study Type: interventional
• Target: 20
• Locations: 1 country
• Sites: 1

Brief Summary

New Zealand blackcurrant (NZBC) is a supplement made from a berry naturally rich in plant compounds called anthocyanins. Researchers have studied these compounds for years and found that they may help the body by improving blood flow, reducing post-exercise stress on the body, and supporting energy production. Most of that research, however, has focused on endurance athletes like runners and cyclists. Almost nothing was known about whether NZBC could benefit people who do strength training. That is what this study was designed to find out. Twenty healthy, resistance-trained men and women between the ages of 18 and 40 were recruited. Each participant completed four different conditions over the course of the study: taking no supplement at all, taking a placebo (a dummy capsule with no active ingredient), taking a low dose of NZBC (250 mg per day for seven days), and taking a higher dose of NZBC (600 mg per day for seven days). Neither the participants nor the researchers evaluating them knew which capsule was being taken at any given time, a design that helps ensure the results are as reliable as possible. At the end of each seven-day period, participants came into the lab and completed a full battery of tests. Measurements included how much weight could be lifted for one maximum effort on the bench press and leg press, how much total volume could be completed across multiple sets, and how fast and powerfully the bar could be moved. Participants also completed a 30-second all-out cycling sprint to test anaerobic fitness, and a paper-and-pencil color-word test to measure focus and mental sharpness. Strength increased noticeably. After taking either dose of NZBC, participants were able to lift more weight on both the bench press and leg press than when taking the placebo or no supplement. The lower dose had a particularly striking effect on leg training: participants pushed through roughly 38% more total volume in their leg press sets. For bar speed and explosive power on the bench press, the higher dose had the edge. Cognitive performance followed a similar pattern. The lower dose sharpened mental performance across several parts of the color-word test, while the higher dose made a more modest but still meaningful difference on one section. The sprint cycling test showed no differences between conditions. Importantly, both doses were safe and well-tolerated, with no meaningful side effects reported throughout the study. One week of supplementation was sufficient to produce real differences in strength, power, and mental sharpness, and neither dose raised any safety concerns.

Conditions

Resistance Exercise Performance; Cognitive Function; Anaerobic Performance; Dietary Supplementation Athletic Performance

Keywords

Blackcurrant; Anthocyanins; Anaerobic Exercise; Cognitive Function; Resistance Training; Dose-Response; Sports Nutrition; Placebo-Controlled

Outcome Measures

Primary Outcomes (2)

• Resistance Exercise Performance

  Bench press and leg press 1RM, total lifting volume (sets × reps × weight), and Tendo-derived peak and mean barbell power during bench press. Assessed at 4 time points across a crossover design (1-week supplementation, 1-week washout). Each measure reported separately in its respective unit (kg for 1RM and volume; watts for power).

  Baseline, end of Week 1 (post-supplementation), end of Week 2 (post-washout), and end of Week 3 (post-crossover supplementation); total study duration approximately 3 weeks.

• Anaerobic Exercise Performance

  Peak power, mean power, and total work were measured via the 30-second Wingate Anaerobic Test. Assessed at 4 time points across a crossover design (1-week supplementation, 1-week washout). Each measure reported separately in its respective unit (watts for peak and mean power; joules for total work).

  Baseline, end of Week 1 (post-supplementation), end of Week 2 (post-washout), and end of Week 3 (post-crossover supplementation)

Secondary Outcomes (6)

• Cognitive Function

  Baseline, end of Week 1 (post-supplementation), end of Week 2 (post-washout), and end of Week 3 (post-crossover supplementation).

• Rating of Perceived Exertion (RPE)

  Baseline, end of Week 1 (post-supplementation), end of Week 2 (post-washout), and end of Week 3 (post-crossover supplementation)

• Heart Rate (HR)

  Baseline, end of Week 1 (post-supplementation), end of Week 2 (post-washout), and end of Week 3 (post-crossover supplementation)

• Systolic Blood Pressure (SBP)

  Baseline, end of Week 1 (post-supplementation), end of Week 2 (post-washout), and end of Week 3 (post-crossover supplementation)

• Diastolic Blood Pressure (DBP)

  Baseline, end of Week 1 (post-supplementation), end of Week 2 (post-washout), and end of Week 3 (post-crossover supplementation)

Study Arms (4)

No-Capsule Control

NO INTERVENTION

No supplement administered. Participants completed all testing procedures without receiving any substance.

Placebo

PLACEBO COMPARATOR

Participants received maltodextrin capsules matched in appearance to the blackcurrant supplement capsules.

Dietary Supplement: Maltodextrin (Placebo)

Low-Dose Blackcurrant

EXPERIMENTAL

Participants received 250 mg of blackcurrant supplement per day.

Dietary Supplement: Low-dose Blackcurrant Supplement

High-Dose Blackcurrant

EXPERIMENTAL

Participants received 600 mg of blackcurrant supplement per day.

Dietary Supplement: High-dose Blackcurrant Supplement

Interventions

Low-dose Blackcurrant Supplement DIETARY_SUPPLEMENT

A low-dose blackcurrant (250 mg) supplement was administered to examine its effects on anaerobic exercise performance and cognitive function.

Low-Dose Blackcurrant

High-dose Blackcurrant Supplement DIETARY_SUPPLEMENT

A high-dose blackcurrant (600 mg) supplement was administered to examine its effects on anaerobic exercise performance and cognitive function.

High-Dose Blackcurrant

Maltodextrin (Placebo) DIETARY_SUPPLEMENT

Maltodextrin capsules matched in appearance to the blackcurrant supplement capsules, serving as an inert placebo control.

Placebo

Eligibility Criteria

• Age: 18 Years - 40 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• Age 18-40 years
• At least 2 years of regular resistance training that included the bench press and either the leg press or squat
• Body mass index (BMI) of 18.5-24.9 kg/m²

You may not qualify if:

• Diagnosed with a metabolic, cardiovascular, or thyroid disorder
• Current use of prescription or over-the-counter agents with potential cardiovascular or neurocognitive effects (e.g., beta-blockers or stimulants)
• Tobacco use, vaping, or smokeless nicotine use
• Self-reported blackcurrant sensitivity
• Habitual alcohol intake greater than 12 standard drinks per week
• Any recent musculoskeletal injury likely to impair testing
• Resting heart rate exceeding 100 bpm at familiarization
• Resting blood pressure ≥140/90 mmHg at familiarization after repeat confirmation
• Body fat percentage exceeding the study's predefined threshold at familiarization

Sponsors & Collaborators

• Jacksonville State University: lead

Study Sites (1)

Exercise Physiology and Nutrition Laboratory (EPNL) at Jacksonville State University

Jacksonville, Alabama, 36265-1724, United States

Location

MeSH Terms

Interventions

maltodextrin

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: DOUBLE
• Who Masked: PARTICIPANT, INVESTIGATOR
• Masking Details: Supplements were coded and prepared by a third party not involved in data collection or analysis, ensuring that neither the participants nor the investigators were aware of the treatment assignment during each session. The statistician performing data analysis was also blinded to group allocation until after all analyses were completed. Unblinding occurred only after the final dataset was locked.
• Purpose: BASIC SCIENCE
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Associate Professor

Study Record Dates

• First Submitted: May 17, 2026
• First Posted: June 2, 2026
• Study Start: January 21, 2023
• Primary Completion: April 25, 2023
• Study Completion: July 10, 2023
• Last Updated: June 2, 2026

Record last verified: 2026-05

Data Sharing

• IPD Sharing: Will share
• Shared Documents: STUDY PROTOCOL, SAP, ICF
• Time Frame: IPD and supporting information will be available beginning 6 months after publication and will remain available for a minimum of 5 years following the publication date."
• Access Criteria: Deidentified IPD will be made available to researchers who submit a methodologically sound request to the corresponding author. Requests should include the proposed use of the data, the research question, and the requester's institutional affiliation. Data will be shared in a standard format (e.g., Excel or SPSS) via secure file transfer.

Locations

US (1)