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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
Date results information initially provided
Type of registration
Prospectively registered

Titles & IDs
Public title
Vitamin C for skin health
Scientific title
The KiwiC for Skin Study: Kiwifruit intervention and delivery of vitamin C to skin
Secondary ID [1] 297203 0
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Skin health 311250 0
Vitamin C nutritional status 311251 0
Condition category
Condition code
Diet and Nutrition 309869 309869 0 0
Other diet and nutrition disorders
Skin 310305 310305 0 0
Normal skin development and function
Skin 310306 310306 0 0
Other skin conditions

Study type
Description of intervention(s) / exposure
The overall aim of this project is to determine whether kiwifruit, as a dietary vitamin C source,
impacts on human skin vitamin C levels. We will undertake a kiwifruit intervention for eight weeks with a group of healthy volunteers with low vitamin C status at baseline, to determine whether increased intake can improve skin vitamin C levels. Plasma and skin vitamin C status will be determined before and after the eight week intervention.
Participants will be given two Sungold kiwifruit per day (average weight 80 g each fruit), to be consumed as raw fruit, at any time during the day. The period of the intervention is 8 weeks.
The participants will be given fruit on a weekly basis, with sufficient fruit for 7 days per pack (14 fruit). Uneaten fruit will be returned at the end of the week. COmpliance will also be determined by monitoring participant plasma vitamin C status (we have previously shown that this should be saturated if two kiwifruit per day are consumed).
Intervention code [1] 313457 0
Treatment: Other
Comparator / control treatment
This is a 'before-and-after' study, with each participant's measures at baseline being used in comparison with the after intervention measure. As such, there is no separate control group. Baseline is established at the beginning of the intervention, which is following a two-week lead-in period. During the two week lead-in the participants will be requested to remove any fruit juice and supplements from their diets. All other dietary parameters to remain unchanged.
Control group

Primary outcome [1] 318819 0
Skin vitamin C status as assessed by HPLC measurement of a small skin biopsy sample taken at baseline and at completion of the intervention.
Timepoint [1] 318819 0
8 weeks post-intervention.
Secondary outcome [1] 366143 0
Plasma vitamin C status
Timepoint [1] 366143 0
8 weeks post-enrolment.

Key inclusion criteria
Inclusion criteria (all required): Aged 18 – 75 years; Low/below average plasma vitamin C levels (<40 µmol/L); Residing in Christchurch for duration of 10 week study.
Minimum age
18 Years
Maximum age
75 Years
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
Exclusion criteria (one required): Fear of needles; Allergy/intolerance to kiwifruit; Taking prescription medication (within past three months); Excessive alcohol consumption (fewer than 21 standard drinks/week); High fruit and vegetable consumption (at least 5 servings per day); Diabetes mellitus; Bleeding disorders; Skin conditions such as eczema; A personal history of abnormal scarring; A Fitzpatrick scale type of 4 or more; Obese (BMI greater than 35 kg/m2).

Study design
Purpose of the study
Allocation to intervention
Non-randomised trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Masking / blinding
Open (masking not used)
Who is / are masked / blinded?

Intervention assignment
Single group
Other design features
Not Applicable
Type of endpoint(s)
Statistical methods / analysis
Comparative analysis of pre- and post-intervention samples. Based on previous studies, the change in plasma vitamin C status expected is significantly different with 5 individuals. For this study we will recruit 12 individuals to also monitor skin ascorbate status, to determine the power required for any future intervention studies monitoring the effects of vitamin C on skin function. .

Recruitment status
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] 21250 0
New Zealand
State/province [1] 21250 0

Funding & Sponsors
Funding source category [1] 301751 0
Commercial sector/Industry
Name [1] 301751 0
Zespri International
Address [1] 301751 0
PO Box 4043
Mount Maunganui South
400 Maunganui Road
Mount Maunganui 3116
Country [1] 301751 0
New Zealand
Funding source category [2] 301870 0
Name [2] 301870 0
The University of Otago, Christchurch
Address [2] 301870 0
PO Box 4345
Christchurch 8011
Country [2] 301870 0
New Zealand
Primary sponsor type
The University of Otago, Christchurch
PO Box 4345
Christchurch 8011
New Zealand
Secondary sponsor category [1] 301496 0
Name [1] 301496 0
The University of Otago, Dunedin
Address [1] 301496 0
PO Box 56
Dunedin 9054
Country [1] 301496 0
New Zealand

Ethics approval
Ethics application status
Ethics committee name [1] 302475 0
Health and Disability Ethics Committees
Ethics committee address [1] 302475 0
Ministry of Health
133 Molesworth Street
Wellington 6011
Ethics committee country [1] 302475 0
New Zealand
Date submitted for ethics approval [1] 302475 0
Approval date [1] 302475 0
Ethics approval number [1] 302475 0

Brief summary
A previous study suggests that the skin responds to increases in plasma vitamin C availability. There appears to be very high vitamin C content in the dermal fibroblasts, the site of collagen formation, confirming the essential nature of vitamin C to support this activity.

Therefore in order to test the effect of diet on skin status, a dietary intervention study is proposed in which individuals are supplemented with kiwifruit, as an excellent dietary source of vitamin C, for two months allowing full plasma saturation to occur. We will measure skin vitamin C content before and after the intervention. To our knowledge there is currently no information of this type available.

We will recruit individuals with low vitamin C status as indicated by a plasma vitamin C level <40 µmol/L. Participants will be supplemented with two Sungold kiwifruit per day for eight weeks; this is equivalent to ~250 mg vitamin C per day. We have previously shown that two Sungold kiwifruit per day is sufficient to achieve plasma saturation within one week of beginning supplementation.

The study will comprise a two week lead-in period to allow the participants’ time to control their dietary vitamin C intakes. This will be followed by an eight week intervention period with kiwifruit. Whole skin biopsies to obtain tissue for the measurement of whole skin vitamin C content will be taken by punch biopsy before and after the kiwifruit intervention.

Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 90346 0
Prof Margreet Vissers
Address 90346 0
Centre for Free Radical Research,
Dept of Pathology and Biomedical Science,
University of Otago, Christchurch,
PO Box 4345,
Christchurch 8011
Country 90346 0
New Zealand
Phone 90346 0
+64 3 364 1524
Fax 90346 0
Email 90346 0
Contact person for public queries
Name 90347 0
Prof Margreet Vissers
Address 90347 0
Centre for Free Radical Research,
Dept of Pathology and Biomedical Science,
University of Otago, Christchurch,
PO Box 4345,
Christchurch 8011
Country 90347 0
New Zealand
Phone 90347 0
+64 3 364 1524
Fax 90347 0
Email 90347 0
Contact person for scientific queries
Name 90348 0
Prof Margreet Vissers
Address 90348 0
Centre for Free Radical Research,
Dept of Pathology and Biomedical Science,
University of Otago, Christchurch,
PO Box 4345,
Christchurch 8011
Country 90348 0
New Zealand
Phone 90348 0
+64 3 364 1524
Fax 90348 0
Email 90348 0

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
What data in particular will be shared?
De-identified results data.
When will data be available (start and end dates)?
From three months and up to 5 years after publication of results.
Available to whom?
Researchers who provide a methodologically sound proposal, on a case-by-case basis at the discretion of Primary Sponsor.
Available for what types of analyses?
Analyses that further the aims of the study, and meta-analyses, with permission from the PI.
How or where can data be obtained?
Access subject to approvals by Principal Investigator, together with a requirement to sign a data access agreement.
What supporting documents are/will be available?
No other documents available
Summary results
Have study results been published in a peer-reviewed journal?
Other publications
Have study results been made publicly available in another format?
Results – basic reporting
Results – plain English summary