Table 2 Summary of questionnaire variables

Demographics

Baseline

Name, address, date of birth, ethnicity, income, educational qualifications

Questions based on Statistics New Zealand Census questions 2013, available from http://archive.stats.govt.nz/Census/2013-census/info-about-the-census/forms-guidenotes.aspx.

Diabetes and cardiovascular disease risk factors

Baseline

History of first-degree relative with type 2 diabetes mellitus. Personal history of gestational diabetes, or polycystic ovarian disease (females only), hypertension, dyslipidaemia, myocardial infarction, stoke, mental illness, ethnicity, smoking

Questions based on Ministry of Health 2016 New Zealand Health Survey Adult Questionnaire (Year 6) 1 July 2016–30 June 2017 with some specific additions. New Zealand Health survey available from https://www.health.govt.nz/publication/content-guide-2016-17-new-zealand-health-survey

History of mental health disorders

Baseline and at 6 and 9 months if newly diagnosed since previously collected

History of anxiety, depression, or other mental health illness; current treatments used

Questions based on Ministry of Health 2016 New Zealand Health Survey Adult Questionnaire (Year 6) 1 July 2016–30 June 2017 with some specific additions. New Zealand Health survey available from https://www.health.govt.nz/publication/content-guide-2016-17-new-zealand-health-survey

Recent major stressful life events

Baseline and at 6 and 9 months

History of stressful life events occurring in the preceding 12 months at baseline, and since last recorded at subsequent time points

The Life Stress scale is adapted from the Pregnancy Risk Assessment Monitoring System (Centers for Disease Control and Prevention, 2009), and is a 13-item measure included to address the occurrence of recent stressful experiences

Medications

All

Name, dose, frequency, route of all prescribed medications (except topical), and specific over-the-counter medications

Developed by researchers coded according to World Health Organization Anatomical Therapeutic Chemical Classification System with Defined Daily Doses [52]

Supplement use

All

Confined to probiotics, prebiotic/fibre, fish oils, and plant sterols supplements; name, frequency of use, types of probiotics and prebiotics contained in relevant supplements

Developed by researchers

Background use of foods which may impact outcomes

All

Confined to foods containing probiotics (yogurt and other fermented foods), oats/corn, artificial sweeteners, foods enriched with plant sterols; frequency of use in past month (at baseline) or since previous visit (all other time points)

Developed by researchers

Professional lifestyle modification or mental health advice

All

Has participant received professional advice about lifestyle interventions or mental health (in previous 12 months at baseline, and since last collected at other time points)

Created by researchers based on questions from Ministry of Health 2016 New Zealand Health Survey Adult Questionnaire (Year 6) 1 July 2016–30 June 2017 with some specific additions. New Zealand Health survey available from https://www.health.govt.nz/publication/content-guide-2016-17-new-zealand-health-survey

3-day food diary

All

All foods and drinks including quantities and methods of preparation over 3 days

Data entered into Foodworks 9 (Xyris Software Australia Pty Ltd)

Physical activity measure

All

Six-point descriptive categorical scale used to assess levels of activity, and in relation to recommended activity guidelines. Categories broadly match activity intensity based on metabolic equivalents.

Stanford Leisure-Time activity categorical Item (L-Cat 2.2) [38]

Smoking

All

Classification as non-smoker, ex-smoker, or current smoker and intensity of current smoking

Developed by researchers

Alcohol and recreational drug use

Baseline and at 6 and 9 months

Frequency of alcohol use and number standard drinks taken of a typical day. Use of substances for recreational or non-medicinal purposes to get high. Identifies substances used and frequency of use

Questions based on Ministry of Health 2016 New Zealand Health Survey Adult Questionnaire (Year 6) 1 July 2016–30 June 2017 with some specific additions. New Zealand Health survey available from https://www.health.govt.nz/publication/content-guide-2016-17-new-zealand-health-survey

Gastrointestinal symptoms

At 3, 6 and 9 months

Changes in frequency of gastrointestinal symptoms including nausea/vomiting, stomach aches, cramps, or pain, bloating or swollen stomach/abdomen, and bowel motions. Evaluation of impact of any changes in bowel pattern.

Developed by researchers

Hospitalizations

At 3, 6 and 9 months

Hospitalizations since previous visit (excluding elective surgery and outpatient appointments)

Developed by researchers

Use of reduced dose of cereals

At 3 and 6 months

Yes/no question to determine if participant usually takes half or less of the daily dose of corn/oats, and powder sachet

Developed by researchers