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Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Date data sharing statement initially provided
Type of registration
Prospectively registered

Titles & IDs
Public title
The bioequivalence of two commerical blackcurrant extracts and the effect of caffeine on the appearance of blackcurrant polyphenolics in blood plasma in healthy participants.
Scientific title
Investigating the polyphenol bioequivalence of a spray-dried blackcurrant powder with a commercial blackcurrant extract and determining the acute effect of caffeine on the polyphenol bioavailability when co-consumed with blackcurrant powder in healthy participants.
Secondary ID [1] 302326 0
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Nutrient absorption 319088 0
Condition category
Condition code
Other 317039 317039 0 0
Research that is not of generic health relevance and not applicable to specific health categories listed above

Study type
Description of intervention(s) / exposure
This is a double-blind, three-arm repeated measures crossover study that will allow us to evaluate the bioequivalence of anthocyanins in human plasma following the consumption of two commercial blackcurrant extracts. Additionally, we seek to determine the effect of co-consuming caffeine with blackcurrant powder on the bioavailability of anthocyanins in human blood plasma. Prospective participants who have passed the study’s inclusion/exclusion criteria will be asked to attend a familiarisation session where they will meet with the study’s principal investigator. During this session, the study’s principal investigator (research scientist, PhD) will explain the purpose of the study and what is expected from them as a participant. They give potential participants a copy of the information sheet and health questionnaire for them to take home and complete.

Recruited participants will be required to complete all three treatment interventions of this study: (1) spray-dried blackcurrant powder, (2) spray-dried blackcurrant powder + caffeine and (3) anthocyanin-enriched blackcurrant extract. The order at which participants will consume the treatments will be randomised. Participants will be instructed to refrain from consuming a list of food, drinks and dietary supplements containing anthocyanins 24 hours before their trial day. On each trail day, participants will be given a standardised breakfast bar to consume with water to have for breakfast 2 hours before the beginning of the trial. On the first trial day, participants will be given their allocated blackcurrant treatment to consume with 250 mL of water as quickly as possible. All blackcurrant treatments will contain a dose of anthocyanins relative to each participant’s bodyweight (3.2 mg total anthocyanins/kg bodyweight). The blackcurrant + caffeine intervention will contain a caffeine dose of 3 mg/kg bodyweight. Venous blood (approximately 5 mL) samples will be collected from participants 0, 1, 2, 4 and 6 hours after consuming their treatment. The trial coordinator (research associate) of this study will be instructing all participants of what is required of them on their trial day.

To monitor participants’ adherence to the dietary restrictions, each participant will be asked to recall if they have consumed any foods containing anthocyanins from a list provided within the last 24 hours prior to starting their trial day. A baseline blood sample will also be collected on each trial day before participants are given their intervention. This will be analysed for anthocyanin and other polyphenolics and will indicate participants’ adherence to the dietary restrictions.

Participants will be required to return to complete the two other trial days where they will be given the intervention that they did not receive on previous trial days. Overall the study duration for each participant is three weeks. Each trial day will last approximately 6.5 hours and each trial day will be separated by at least five days.
Intervention code [1] 318614 0
Treatment: Other
Comparator / control treatment
The bioavailability profile of anthocyanins following the consumption of the spray-dried blackcurrant powder and spray-dried blackcurrant powder + caffeine will be compared with the bioavailability profile of anthocyanins following consumption of anthocyanin-enriched blackcurrant extract (reference comparator).

A single serve of a commercially available anthocyanin-enriched extract will be given to participants on the trial day to consume with 200 mL of water. A serve will contain a dose equivalent to 3.2 mg total anthocyanins/kg bodyweight. All interventions will be consumed on-site in the human clinical facility with all interventions prepared in a food safe facility by a trained technician who is a member of the research team.
Control group

Primary outcome [1] 325140 0
Plasma anthocyanin concentrations will be measured in blood samples collected from all participants at the same timepoints on all trial days.
Timepoint [1] 325140 0
This will be measured from blood samples collected at 0, 1, 2, 4 and 6 hours after treatment consumption during each trial day using validated in-house high performance liquid chromatography (HPLC) methods.
Secondary outcome [1] 386976 0
Blood glucose levels
Timepoint [1] 386976 0
On each trial day, blood glucose levels will be measured from an aliquot of venous blood samples collected at 0, 1, 2, 4 and 6 hours after treatment consumption. Glucose will be measured using "point-of-test" biosensors.

Key inclusion criteria
Healthy individuals (male or female) 18 – 55 years who are able to provide written consent to participate in this study will be selected from this study.
Minimum age
18 Years
Maximum age
55 Years
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
Participants will be excluded if they are unwilling or unable to provide written consent or comply with the study procedures. Participants will also be excluded if they have known hypersensitivity or intolerance to caffeine, blackcurrants or berryfruit-derived products. In addition, participants will be excluded if they are pregnant, planning to get pregnant in the immediate future or have any of the following conditions: (i) blood borne diseases (e.g. hepatitis), (ii) clinically diagnosed high/low blood pressure, (iii) recent bacterial or viral illness or (iv) are taking medication that affects the properties of blood (e.g. blood clotting).

Study design
Purpose of the study
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
This a double blinded repeated measures crossover study. Participants will be allocated a unique numeric code upon recruitment. Participants will be required to consume all dietary interventions in this study, but the order at which they will be consumed will be randomised. The randomisation and allocation of treatment for each participant will be undertaken by a statistician who is not involved in this study. Participant treatment allocation is held and concealed until completion of the trial and analysis of the data is finished. Dietary interventions will be served in opaque food safe drink bottles labelled with the participant's unique numeric code.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Order of treatment allocation of participants into the three dietary treatment groups will be performed using a spreadsheet random function.
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?
The people receiving the treatment/s
The people administering the treatment/s
The people assessing the outcomes
The people analysing the results/data
Intervention assignment
Other design features
Not Applicable
Type of endpoint(s)
Statistical methods / analysis
Data will be expressed as mean +/- standard error. ANOVA analysis of anthocyanin bioavailability data will be conducted to determine time and treatment interactions between anthocyanin-enriched blackcurrant extract, spray-dried blackcurrant extract, and spray-dried blackcurrant extract + caffeine interventions .

Recruitment status
Not yet recruiting
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment outside Australia
Country [1] 22990 0
New Zealand
State/province [1] 22990 0

Funding & Sponsors
Funding source category [1] 306749 0
Government body
Name [1] 306749 0
The New Zealand Institute for Plant & Food Research Ltd.
Address [1] 306749 0
The New Zealand Institute for Plant & Food Research Ltd.
Batchelar Road,
Palmerston North 4474
Country [1] 306749 0
New Zealand
Primary sponsor type
Dr. Dominic Lomiwes
The New Zealand Institute for Plant & Food Research Ltd.
Batchelar Road,
Palmerston North 4474
New Zealand
Secondary sponsor category [1] 307303 0
Name [1] 307303 0
Address [1] 307303 0
Country [1] 307303 0

Ethics approval
Ethics application status
Ethics committee name [1] 306921 0
Health and Disability Ethics Committees
Ethics committee address [1] 306921 0
Ministry of Health
133 Molesworth Street
PO Box 5013
Wellington 6011
Ethics committee country [1] 306921 0
New Zealand
Date submitted for ethics approval [1] 306921 0
Approval date [1] 306921 0
Ethics approval number [1] 306921 0

Brief summary
There is growing evidence for the efficacy of supplementation with anthocyanin-rich foods in supporting exercise performance and cognition. In these studies, the dose and timing of supplementation were critical considerations to ensure the delivery and appropriate dose of anthocyanins to confer their functional benefits. New Zealand blackcurrants are rich in anthocyanins and have a unique profile from other berryfruit. In previous bioavailability studies, we reported that the anthocyanins are temporally bioavailable for several hours after blackcurrant extract consumption where it peaks at 2 hours post-consumption. Depending on the processing procedure of blackcurrants extract, the final food product may vary in properties (i.e. water solubility) and may contain other constituents such as maltodextrin in spray-dried extracts. These considerations are important as the food matrix may influence the rate and extent at which anthocyanins are absorbed by the body, even though the same dose of anthocyanin is consumed.

Caffeine is one of numerous scientifically supported supplements known to have an ergogenic effect on physical and cognitive performance through their ability to stimulate the central nervous system and regulate mitochondrial function. Given the evidence for the effect of blackcurrants in regulating these mechanisms, it is possible that caffeine can synergistically improve physical and cognitive performance when co-ingested with blackcurrants compared with blackcurrants alone. Whether co-ingestion of caffeine interferes with blackcurrant anthocyanin delivery, however, is unclear and will need to be established to reveal whether caffeine and blackcurrant anthocyanins are synergistic in supporting physical and cognitive performance.

In this study, we seek to investigate the bioequivalence of anthocyanins in human plasma following the consumption of a single dose of a spray-dried blackcurrant powder compared to anthocyanin-enriched blackcurrant extract. Furthermore, we also aim to investigate the effect of co-consuming caffeine with blackcurrant powder on the bioavailability of anthocyanins in human blood plasma.
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 105454 0
Dr Dominic Lomiwes
Address 105454 0
The New Zealand Institute of Plant & Food Research Ltd.
Batchelar Road
Private Bag 11600
Palmerston North 4442
Country 105454 0
New Zealand
Phone 105454 0
+64 6 355 6113
Fax 105454 0
Email 105454 0
Contact person for public queries
Name 105455 0
Mr Brendan Vercoe
Address 105455 0
The New Zealand Institute of Plant & Food Research Ltd.
120 Mt Albert Road
Mt Albert
Auckland 1025
Country 105455 0
New Zealand
Phone 105455 0
+64 9 925 7223
Fax 105455 0
Email 105455 0
Contact person for scientific queries
Name 105456 0
Dr Dominic Lomiwes
Address 105456 0
The New Zealand Institute of Plant & Food Research Ltd.
Batchelar Road
Private Bag 11600
Palmerston North 4442
Country 105456 0
New Zealand
Phone 105456 0
+64 6 355 6113
Fax 105456 0
Email 105456 0

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
No/undecided IPD sharing reason/comment
Ethics requirements for human clinical studies do not allow us to release data that may risk the disclosure of the identity of participants who took part in this study.. Furthermore, has potential commercial outcomes and publicly disclosing participant data will jeopordise the company's ability to protect the intellectual property generated from this study.
What supporting documents are/will be available?
Ethical approval
How or where can supporting documents be obtained?
Type [1] 9177 0
Ethical approval
Citation [1] 9177 0
Link [1] 9177 0
Email [1] 9177 0
Other [1] 9177 0
Our ethics application has now been submitted and is yet to be approved. Once we have obtained ethics approval, the letter from the committee confirming this will be uploaded as evidence that ethics approval has been granted for this study.
Attachment [1] 9177 0
Summary results
No Results