ANZCTR - Registration

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Trial registered on ANZCTR

Registration number

ACTRN12613000989741

Ethics application status

Approved

Date submitted

3/09/2013

Date registered

5/09/2013

Date last updated

28/10/2016

Type of registration

Prospectively registered

Titles & IDs

Public title

The effects of kiwifruit supplementation on neutrophil and sperm function in young adult males low in vitamin C: implications for immunity and fertility

Scientific title

The effects of kiwifruit supplementation on neutrophil and sperm function in young adult males low in vitamin C: implications for immunity and fertility

Secondary ID [1]

None

Universal Trial Number (UTN)

U111-1146-5950

Trial acronym

Linked study record

Health condition

Health condition(s) or problem(s) studied:

Immunity

Fertility

Condition category

Condition code

Inflammatory and Immune System

Normal development and function of the immune system

Reproductive Health and Childbirth

Fertility including in vitro fertilisation

Diet and Nutrition

Other diet and nutrition disorders

Intervention/exposure

Study type

Interventional

Description of intervention(s) / exposure

Participants will be supplemented with two export-grade gold kiwifruit/day for four weeks. Compliance will be monitored by measuring plasma vitamin C levels every week.

An extension period will comprise supplementation with 250 mg/d vitamin C tablets for two months. Compliance will be determined by counting remaining tablets.

Intervention code [1]

Other interventions

Comparator / control treatment

No control group

Control group

Uncontrolled

Outcomes

Primary outcome [1]

Neutrophil function:
- apoptosis quantified by double staining of cells with propidium iodide and Annexin V-FITC, and fluorescence-activated cell sorting (FACS)
- bacterial killing by neutrophils cocultured with S. aureus and measuring loss of bacterial colony-forming units using the fluorescent membrane potential dye DiOC2
- neutrophil chemotaxis assayed using Falcon Fluoroblok inserts and a fluorescence plate reader
- neutrophil extracellular traps production measured using the membrane impermeable DNA binding dye Syntox Green and fluorescence microscopy

Timepoint [1]

pre- and post-intervention (4 weeks)

Primary outcome [2]

Sperm function:
- WHO fertility criteria e.g. volume, count, motility, vitality
- metabolic activity of mitochondria measured using a Seahorse XF extracellular analyser
- oxidative stress determined by oxidative state of peroxiredoxins measured using SDS-PAGE and western blotting
- sperm chromatin structure assay measured using FACS

Timepoint [2]

Pre-intervention, post-intervention (4 weeks) and post vitamin C tablet supplementation period (3 months)

Primary outcome [3]

Vitamin C content of plasma, neutrophils and semen measured using HPLC with electrochemical detection

Timepoint [3]

Pre-intervention and post-intervention (4 weeks) for plasma, neutrophil and semen vitamin C levels, and post vitamin C tablet supplementation period (3 months) for plasma and seminal vitamin C levels only

Secondary outcome [1]

General health (SF-36 questionnaire)

Timepoint [1]

Pre- and post-intervention (4 weeks)

Secondary outcome [2]

Urate and allantoin content of plasma and semen measured using UHPLC with stable isotope dilution mass spectrometry

Timepoint [2]

Pre- and post-intervention (4 weeks)

Secondary outcome [3]

Myeloperoxidase content of plasma and semen measured using ELISA

Timepoint [3]

Pre- and post-intervention (4 weeks)

Eligibility

Key inclusion criteria

Male aged 18-35 years
Non-smoker
Plasma vitamin C <50 umol/L
Residing in Christchurch for the duration of the study

Minimum age

18 Years

Maximum age

35 Years

Sex

Males

Can healthy volunteers participate?

Yes

Key exclusion criteria

allergy/intollerance to kiwifruit
recent smoker (within previous year)
taking vitamin C supplements (within past 3 months)
taking prescription medication (within past 3 months)
excessive alcohol consumption (>21 std drinks/week)
high fruit and vegetable consumption (>5 servings/d)
diabetes mellitus
bleeding disorgers
fainting due to fear of needles

Study design

Purpose of the study

Educational / counselling / training

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

Who is / are masked / blinded?

Intervention assignment

Other design features

Phase

Type of endpoint/s

Statistical methods / analysis

Recruitment

Recruitment status

Completed

Date of first participant enrolment

Anticipated

1/10/2013

Actual

15/10/2013

Date of last participant enrolment

Anticipated

Actual

11/12/2013

Date of last data collection

Anticipated

Actual

17/02/2014

Sample size

Target

Accrual to date

Final

Recruitment outside Australia

Country [1]

New Zealand

State/province [1]

Canterbury

Funding & Sponsors

Funding source category [1]

Government body

Name [1]

Ministry of Business, Innovation & Employment (MBIE)

Address [1]

33 Bowen Street, Wellington 6011

Country [1]

New Zealand

Funding source category [2]

Commercial sector/Industry

Name [2]

Zespri International Ltd

Address [2]

PO Box 4043
400 Maunganui Road
Mount Maunganui 3149

Country [2]

New Zealand

Primary sponsor type

University

Name

University of Otago, Christchurch

Address

PO Box 4345
2 Riccarton Avenue
Christchurch 8140

Country

New Zealand

Secondary sponsor category [1]

None

Name [1]

Address [1]

Country [1]

Ethics approval

Ethics application status

Approved

Ethics committee name [1]

Health and Disability Ethics Committees

Ethics committee address [1]

C/- MEDSAFE, Level 6, Deloitte House
10 Brandon Street
PO Box 5013
Wellington

Ethics committee country [1]

New Zealand

Date submitted for ethics approval [1]

15/08/2013

Approval date [1]

22/08/2013

Ethics approval number [1]

13/STH/105

Summary

Brief summary

Vitamin C is an essential nutrient which is not produced in humans and consequently must be obtained through dietary sources.  Vitamin C is required in all body tissues for optimal activity of a number of essential biosynthetic and regulatory enzymes.  We are particularly interested in the role that vitamin C may play in immunity and fertility, through enhancement of white blood cell (neutrophil) and sperm function.  

Kiwifruit are an outstanding commonly available source of vitamin C.  We have recently carried out human intervention studies investigating the bioavailability of kiwifruit-derived vitamin C.  We found that two kiwifruit per day were required to saturate plasma and thus provide “optimal” vitamin C levels.  Neutrophil and seminal vitamin C levels were also increased significantly with two kiwifruit per day.  Furthermore, we have shown that kiwifruit-derived vitamin C has equivalent bioavailability to synthetic vitamin C supplements.

The aim of our current study is to investigate the effects of kiwifruit-derived vitamin C on neutrophil and sperm function.  We will supplement young men low in vitamin C with two kiwifruit per day for one month and measure neutrophil and sperm function before and after intervention.  Specifically, we will determine the effects of the intervention on neutrophil cell death, bacterial killing, formation of extracellular traps and neutrophil chemotaxis.  We will also determine the effects of the intervention on specific sperm parameters such as viability, motility, agglutination, mitochondrial function, markers of oxidative stress, and chromatin structure.   The vitamin C status of the participants’ blood plasma will be monitored weekly for the duration of the study.  

Overall, the proposed study will provide valuable information as to how vitamin C affects neutrophil and sperm function and thus potentially impact on immunity and fertility.

Trial website

Trial related presentations / publications

Enhanced human neutrophil vitamin C status, chemotaxis and oxidant generation following dietary supplementation with vitamin C-rich SunGold kiwifruit.
Bozonet SM, Carr AC, Pullar JM, Vissers MC.
Nutrients. 2015 Apr 9;7(4):2574-88. doi: 10.3390/nu7042574.

Public notes

Contacts

Principal investigator

Name

Prof Margreet Vissers

Address

University of Otago, Christchurch
2 Riccarton Avenue
PO Box 4345
Christchurch 8140

Country

New Zealand

Phone

64 3 364 1524

Fax

margreet.vissers@otago.ac.nz

Contact person for public queries

Name

Anitra Carr

Address

University of Otago, Christchurch
2 Riccarton Avenue
PO Box 4345
Christchurch 8140

Country

New Zealand

Phone

64 3 364 0649

Fax

anitra.carr@otago.ac.nz

Contact person for scientific queries

Name

Anitra Carr

Address

University of Otago, Christchurch
2 Riccarton Avenue
PO Box 4345
Christchurch 8140

Country

New Zealand

Phone

64 3 364 0649

Fax

anitra.carr@otago.ac.nz

No information has been provided regarding IPD availability

What supporting documents are/will be available?

No Supporting Document Provided

Results publications and other study-related documents

Documents added manually

No documents have been uploaded by study researchers.

Documents added automatically

Source	Title	Year of Publication	DOI
Embase	Enhanced human neutrophil vitamin C status, chemotaxis and oxidant generation following dietary supplementation with vitamin C-rich SunGold kiwifruit.	2015	https://dx.doi.org/10.3390/nu7042574
Dimensions AI	Marginal Ascorbate Status (Hypovitaminosis C) Results in an Attenuated Response to Vitamin C Supplementation	2016	https://doi.org/10.3390/nu8060341
Embase	Elevated seminal plasma myeloperoxidase is associated with a decreased sperm concentration in young men.	2017	https://dx.doi.org/10.1111/andr.12327

N.B. These documents automatically identified may not have been verified by the study sponsor.

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