Fruits, Vegetables, and Whole Grains: A Community-based Intervention
Governments and major national agencies throughout the western world concerned with chronic
disease prevention (heart disease, stroke, diabetes, and cancer) uniformly advocate
increased intakes of fruit, vegetables and whole grain cereals. All also agree that body
weight reduction is central to reducing the risk of heart disease, stroke, type 2 diabetes,
and certain cancers. Nevertheless, there is no official advice encouraging increased
consumption of these foods in order to achieve and maintain a healthy body weight. Most
importantly, there are no intervention studies that have tested the assumption that
increased intake of fruit, vegetables and whole grain cereals will promote a healthier body
weight. Our study will therefore address this issue to determine the effect of an increased
intake of fruit, vegetables, and whole grain cereals on body weight, the intensity of effort
required to achieve compliance, the durability of this habit, genetic determinants, and the
effect on biomarkers of chronic disease risk.
We will ask approximately 780 families to take part in this study. We will invite households
to take part if there is at least one adult who is eligible for our study, and who agrees to
To be eligible for this study, participants must be at least 18 years old and have no
medical conditions that would make it unsafe for them to take part. Before beginning the
study, the medical history and other measures will be checked to ensure participant safety
and suitability for participating in the study.
This study consists of three parts. If agreement to participate is given, the first part is
to make an appointment to come to our study clinic to give a fasting blood sample (baseline
measurements), about 40mL of blood. The clinic visit will last approximately 40 minutes. All
participants will be asked to complete a short checklist about their medical history, which
includes information to make sure that they and their household are eligible for
participation. Body fat measurements will also be made using a non-invasive, very simple
machine called Futrex as well as height, weight, waist-to-hip ratio, and blood pressure.
Part of the blood sample will be used for a health screen to ensure subject safety and
suitability for participating in the study. Blood samples will be stored in a secured
location and analyzed at the end of the study for cholesterol levels and other risk factors
for heart disease. Part of the blood sample will be used in DNA analysis to help us
understand the genes related to food intake and metabolism. We will also ask all
participants to complete a questionnaire package about their eating habits and their
physical activity either prior to the clinic visit or at the end of the clinic visit. Once
the questionnaires are completed and returned to the study office, the second part of the
study will commence.
The second part is the intervention itself, lasting six months. If households are deemed to
be eligible, they will be 'randomized' into one of eight study groups with all groups
receiving Canada's Food Guide & Physical Activity Guide. The study groups involve a
combination of different kinds of dietary advice and provision of fruit, vegetables, and
whole grain cereals.
- Treatment 1: no food provision or dietary advice.
- Treatment 2: food delivery.
- Treatment 3: counseling on fruit, vegetables and whole grains.
- Treatment 4: counseling to reduce soft drink intake.
- Treatment 5: food delivery AND counseling on fruit, vegetables and whole grains.
- Treatment 6: food delivery AND counseling to reduce soft drink intake.
- Treatment 7: counseling on fruit, vegetables, whole grains AND counseling on the
reduction of soft drink intake.
- Treatment 8: food delivery AND counseling on fruit, vegetables, whole grains AND
counseling on the reduction of soft drink intake.
All food boxes are prepared and delivered by Food Share, a Toronto-based non-profit
organization that has an existing system for home delivery of nutritious food boxes. If
participants do receive dietary counseling, it will involve a phone call once a week for the
first month (for about 20 minutes) then a phone call once a month for the next 5 months. At
the end of six months, participants will be asked to fill in provided questionnaires and
return to the clinic to repeat the procedures.
The third part is a follow-up 12 months after the end of the intervention. Again,
participants will be asked to fill in provided questionnaires and return to the clinic to
repeat the procedures.
Allocation: Randomized, Endpoint Classification: Efficacy Study, Intervention Model: Factorial Assignment, Masking: Open Label, Primary Purpose: Treatment
Daivd JA Jenkins, MD, PhD
University of Toronto, St. Michael's Hospital
Canada: Canadian Institutes of Health Research