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Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Type of registration
Retrospectively registered

Titles & IDs
Public title
Cognitive and heart health benefits of chewing after eating green leafy vegetables
Scientific title
Cognitive and heart health benefits of chewing after eating green leafy vegetables in healthy men and women
Secondary ID [1] 253160 0
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Cardiovascular disease 258708 0
Cognitive function 258709 0
Condition category
Condition code
Cardiovascular 258863 258863 0 0
Coronary heart disease
Diet and Nutrition 258864 258864 0 0
Other diet and nutrition disorders
Cardiovascular 258865 258865 0 0

Study type
Description of intervention(s) / exposure
A randomized controlled crossover-design trial will be conducted to investigate the acute effects of chewing gum on metabolism of nitrogen oxides, as well as neurocognitive performance outcome measures and endothelial function.

Each participant will complete 2 visits in random order with a minimum of one week washout between each visit. Prior to each visit participants will be asked to consume a standard meal for dinner. For each visit participants will attend the School of Medicine and Pharmacology Research Unit at Royal Perth Hospital in the morning after standard low nitrate breakfast. They will be randomly allocated to:
1. No chewing
2. Chewing
Participants will consume a standardized lunch containing a fixed level of nitrate derived from spinach. They will begin chewing gum 30 minutes after lunch and continue chewing for 2 hours. A fruit-flavoured, sugar-free chewing gum will be used.
Intervention code [1] 257664 0
Treatment: Other
Comparator / control treatment
No chewing after a standardised lunch containing a fixed level of nitrate derived from spinach.
Control group

Primary outcome [1] 259718 0
Plasma nitrite concentration measured using gas chromatography-mass spectrometry
Timepoint [1] 259718 0
Baseline and 2 hours after lunch
Primary outcome [2] 259719 0
Nitric oxide status assessed by measuring plasma S-nitrosothiols
Timepoint [2] 259719 0
Baseline and 2 hours after lunch
Secondary outcome [1] 266448 0
Salivary nitrate and nitrite concentrations measured using gas chromatography-mass spectrometry
Timepoint [1] 266448 0
Baseline and 45 minutes after lunch
Secondary outcome [2] 266449 0
Blood pressure measured using an automated blood pressure monitor
Timepoint [2] 266449 0
Baseline and 60, 90 and 120 minutes after lunch
Secondary outcome [3] 266450 0
Neurocognitive performance assessed using the COMPASS neuropsychological test battery.
Timepoint [3] 266450 0
Baseline and 1 hour after lunch
Secondary outcome [4] 266451 0
Endothelial function assessed by measuring flow-mediated dilatation of the brachial artery using ultrasound.
Timepoint [4] 266451 0
Baseline and 90 minutes after lunch

Key inclusion criteria
Healthy men and women aged 20 to 70 years
Minimum age
20 Years
Maximum age
70 Years
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
1.Current or recent (<12 months) smoking
2.Body mass index < 18 or > 35 kg/m2,
3.History of cardiovascular or peripheral vascular disease,
4.A systolic blood pressure below 100 or above 160 mmHg
5.A diastolic blood pressure below 50 or above 100 mmHg
6.Diagnosed diabetes, and non-diabetic individuals with fasting plasma glucose concentrations greater than or equal to 5.5 mmol/L,
7.A psychiatric illness,
8.Other major illnesses such as cancer,
9.Current or recent (within previous 6 months) significant weight loss or gain (> 6% of body weight),
10.Reported lactating, pregnant or wishing to become pregnant during the study,
11.Alcohol intake > 210 g per wk for women and > 280 g per wk for men, and
12.Inability or unwillingness to consume foods/beverages provided.
13.Unwillingness to stop the use of supplements 24 hours prior to the testing day.
14.Have any health conditions that would affect food metabolism including the following: food allergies, kidney disease, liver disease and/or gastrointestinal diseases (e.g Irritable bowel syndrome, celiac disease, peptic ulcers)
15.Unable or unwilling to chew gum for 2 hours
16.Unwilling to give up the use of mouth wash while partaking in the study

Study design
Purpose of the study
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
The treatment order for eligible individuals will be randomly assigned using computer generated random numbers. The treatment order allocation will be sealed in numbered envelopes. The envelopes will be used for randomisation by opening an envelope, in consecutive order, as participants are entered in the study. The envelopes will be held by an independent person within the University of Western Australia. The study coordinator will contact the independent person to obtain the next available envelope once an individual is deemed eligible. The envelope will be opened and the code will be recorded.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Computer-generated random numbers using Microsoft Excel
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?

Intervention assignment
Other design features
Not Applicable
Type of endpoint(s)
Statistical methods / analysis

Recruitment status
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment in Australia
Recruitment state(s)

Funding & Sponsors
Funding source category [1] 258136 0
Government body
Name [1] 258136 0
Address [1] 258136 0
National Health and Medical Research Council
GPO Box 1421
ACT 2601
Country [1] 258136 0
Funding source category [2] 258137 0
Commercial sector/Industry
Name [2] 258137 0
The Wrigley Company
Address [2] 258137 0
410 North Michigan Avenue
Chicago, Illinois 60611
Country [2] 258137 0
United States of America
Primary sponsor type
University of Western Australia
The University of Western Australia
35 Stirling Highway
WA 6009
Secondary sponsor category [1] 257306 0
Name [1] 257306 0
Address [1] 257306 0
Country [1] 257306 0

Ethics approval
Ethics application status
Ethics committee name [1] 260116 0
University of Western Australia Human Research Ethics Committee
Ethics committee address [1] 260116 0
The University of Western Australia
35 Stirling Highway
WA 6009
Ethics committee country [1] 260116 0
Date submitted for ethics approval [1] 260116 0
Approval date [1] 260116 0
Ethics approval number [1] 260116 0

Brief summary
This project aims to investigate if chewing gum will increase circulating nitrite and nitric oxide and if these effects are associated with cognitive and vascular benefits.
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 31952 0
Prof Jonathan Hodgson
Address 31952 0
University of Western Australia
GPO Box X2213 Perth WA 6847
Country 31952 0
Phone 31952 0
+61 8 9224 0267
Fax 31952 0
Email 31952 0
Contact person for public queries
Name 15199 0
Dr Catherine Bondonno
Address 15199 0
University of Western Australia
GPO Box X2213 Perth WA 6847
Country 15199 0
Phone 15199 0
+61 8 9224 0342
Fax 15199 0
Email 15199 0
Contact person for scientific queries
Name 6127 0
Dr Catherine Bondonno
Address 6127 0
University of Western Australia
GPO Box X2213 Perth WA 6847
Country 6127 0
Phone 6127 0
+61 8 9224 0342
Fax 6127 0
Email 6127 0

No information has been provided regarding IPD availability
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