Skip to main content
OpenTrials
Completed

NCT Number: NCT03952338

Impact of BC Farmers' Market Nutrition Coupon Program on Diet Quality and Psychosocial Well-being of Low-income Adults

The British Columbia (BC) Farmers' Market Nutrition Coupon Program (FMNCP) provides low-income households with $21/week in coupons to purchase healthy foods at farmers' markets and supportive nutrition skill-building activities. This randomized controlled trial will assess the impact of the BC FMNCP on the overall diet quality (primary outcome), diet quality subscores, mental well-being, sense of community, experiences of food insecurity, risk of malnutrition (secondary outcomes) and subjective social status (exploratory outcome) of low-income adults immediately post-intervention and 16 weeks post-intervention.

Completed

Looking for future studies?

Notify Me

Key information

Conditions

Diet, Healthy Behavior Health Behavior Health Risk Behaviors

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Community Partners

Rural and Urban, British Columbia, Canada

About this study

Background: The British Columbia (BC) Farmers' Market Nutrition Coupon Program (FMNCP) is a healthy eating initiative funded by the BC Ministry of Health. The program provides low-income households with $21/week in coupons to purchase healthy foods at farmers' markets and supportive nutrition skill-building activities. It is not clear if the BC FMNCP is achieving its aims of improving the diet quality, well-being and health of low-income adults, as its outcomes have not been investigated, and studies of similar programs are limited by weak designs that cannot demonstrate causality. This randomized controlled trial will assess the impact of the FMNCP on the overall diet quality (primary outcome), diet quality subscores, mental well-being, sense of community, experiences of food insecurity, risk of malnutrition (secondary outcomes) and subjective social status (exploratory outcome) of low-income adults immediately post-intervention and 16 weeks post-intervention. A qualitative investigation will also explore mechanisms of action and strategies to maximize positive program impacts.

Methods: Low-income adults (≥ 18 years) from up to 15 rural and urban communities will be randomized to a FMNCP intervention (n=132) or a no-intervention control group (n=132), with a 1:1 allocation ratio. An independent researcher from the Clinical Research Unit at the University of Calgary will generate a blocked randomization sequence that stratifies participants into blocks according to sex (male, female), geographic location (rural, urban), pregnancy (yes, no) and breastfeeding (yes, no). In the existing BC FMNCP, community partners distribute one to two sheets of coupons per week (each sheet contains $21 in coupons) to program participants for a total of 16 sheets. Coupons can be used over 16-20 weeks to purchase fruits, vegetables, dairy, meat/poultry/fish, eggs, nuts, and cut herbs at participating BC farmers' markets. However, to allow sufficient time to recruit participants for this study, community partners will distribute 16 coupon sheets to the FMNCP group over 10-15 weeks (households with 5-8 individuals will receive 32 coupon sheets). To ensure participants receive all 16 coupon sheets, community partners will provide two coupon sheets per household during the first 1-6 weeks of the intervention. Participants in the FMNCP group will also be invited to participate in nutrition skill-building activities (e.g., cooking classes). At baseline (0 weeks), immediately post-intervention (10-15 weeks) and 16 weeks post-intervention (26-31 weeks), participants will access a pilot-tested web-based platform to report sociodemographics, health-related variables, mental well-being, sense of community, experiences of food insecurity, risk of malnutrition and subjective social status. Dietary intake will be assessed via two 24-hour dietary recalls at each time point using the Automated Self-Administered Dietary Assessment Tool for Canada (ASA24-Canada-2018). Diet quality scores will be calculated using the Healthy Eating Index-2015. In addition, immediately post-intervention only, participants will report whether they received FMNCP coupons and attended nutrition skill-building activities (to assess contamination of the control group), how often and how much of their own money was spent at farmers' markets during the intervention period and the types of foods purchased.

Data analysis: Descriptive analyses will be conducted to examine participant characteristics by group at each time point. Characteristics of study completers (i.e., provided data 16-weeks post-intervention) and non-completers will also be compared.

Analyses will be intention-to-treat, in which participants will be analysed within the groups to which they were randomized regardless of adherence (e.g., failure to redeem coupons) or dropout. The analyses will include all participants who provided data at baseline. Repeated measures mixed-effect regression will assess differences in mean HEI-2015 scores, HEI-2015 subscores, mental well-being, sense of community, and subjective social status between the FMNCP and control groups immediately post-intervention and 16-weeks post-intervention. Repeated measures multinomial logistic regression will be used to assess differences in the odds of experiencing household food insecurity and risk of malnutrition for the FMNCP group compared to the control group immediately post-intervention and 16-weeks post-intervention. Statistical models will include intervention group (FMNCP vs control), time from baseline, intervention-by-time interaction, blocking variables (i.e., sex, rural/urban, pregnancy, breastfeeding), baseline values of the outcome, and household size as fixed effects covariates. Participant-specific (i.e., repeated measures) variations in outcomes will be modeled using random effects. Models will also include covariates specific to each outcome to increase the precision of estimates (86). For the primary outcome of overall diet quality, models will include the following: children living in the home (yes, no), sex, age, BMI, marital status, race/ethnicity, perceived health, smoking, day of data collection, and educational level. Adjusted group differences (i.e., FMNCP group vs control group) in outcomes will be estimated using 95% confidence intervals and corresponding p-values.

Subgroup analyses will examine whether the impact of the intervention on primary and secondary outcomes differs according to age group or sex. Dose-response analyses will examine whether the impact of the BC FMNCP on overall diet quality depends on the number of coupons redeemed and the number of nutrition skill-building activities attended. Interactions will be retained in statistical models if p<0.10. Analyses will be conducted in Stata (v15.1, Stata Corp, TX, USA), with p<0.05 indicating statistically significant differences between groups. Data interpretation will jointly consider effect sizes, confidence intervals and statistical significance.

Expected outcomes: Findings will show whether and how a scalable population-level policy that links the agricultural and health sectors influences diet quality, psychosocial well-being and other outcomes among low-income adults. Study findings will inform program adjustments to improve participant outcomes. Other jurisdictions can use these data to determine whether and how to initiate similar programs.

Post-hoc analysis: In a post-hoc analysis, a random forest model will be used to explore heterogeneity of program effects on diet quality (total HEI-2015 scores) among different subgroups of FMNCP study participants. Candidate predictors entered into the algorithm will include all variables examined at baseline, including sociodemographic characteristics (e.g., age, sex, and income) and health-related variables (e.g., self-rated health and smoking). The outcome of the random forest analysis will be total HEI-2015 scores for both the FMNCP and control groups.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Individuals will be eligible to participate if they meet the following criteria:

  • Adults (age ≥ 18 years)
  • Low-income as determined by community-specific thresholds (~$18,000/year annual household income before taxes)
  • No expected change in household income prior to study completion (March 2020)
  • 8 or fewer people living in the home (including the participant)
  • No expected change in household composition prior to study completion (March 2020)
  • Primary food shopper for the household
  • Does not have self-reported dementia or Alzheimer's Disease
  • Able to speak, read and write in English (or have someone who can assist them)
  • No plans to move from principal residence prior to study completion (March 2020)
  • Has not previously participated in the BC FMNCP

Exclusion criteria

  • Does not meet one or more inclusion criteria

Treatment and study plan

Food coupons

Other

Participants will receive 16 coupon sheets (each sheet contains $21 in coupons) over 10-15 weeks (households with 5-8 individuals will receive 32 coupon sheets) to purchase fruits, vegetables, dairy, meat/poultry/fish, eggs, nuts, and cut herbs at participating BC farmers' markets.

Nutrition skill-building

Other

Participants will be invited to participate in nutrition skill-building activities throughout the intervention period. To be consistent with the real-world program, the frequency and types of skill-building activities offered will vary by community partner, and participation is not required.

Primary outcomes

  1. Difference Between Intervention and Control Groups in Mean Overall Diet Quality by Healthy Eating Index-2015 Scores Immediately Post-intervention (10-15 Weeks)

    Time frame: post-intervention (10-15 weeks).

    Difference between intervention and control groups in mean overall diet quality by Healthy Eating Index-2015 scores immediately post-intervention (10-15 weeks). Healthy Eating Index-2015 scores are calculated from 24-hour dietary recalls and can range from 0-100, with a higher score indicating higher diet quality.

  2. Difference Between Intervention and Control Groups in Mean Overall Diet Quality by Healthy Eating Index-2015 Scores at 16 Weeks Post-intervention (26-31 Weeks)

    Time frame: 16 weeks post-intervention (26-31 weeks).

    Difference between intervention and control groups in mean overall diet quality by Healthy Eating Index-2015 scores at 16 weeks post-intervention (26-31 weeks). Healthy Eating Index-2015 scores are calculated from 24-hour dietary recalls and can range from 0-100, with a higher score indicating higher diet quality.

Secondary outcomes

  1. Difference Between Intervention and Control Groups in Mean Mental Well-being Scores by Warwick-Edinburgh Mental Well-Being Scale Immediately Post-intervention (10-15 Weeks)

    Time frame: post-intervention (10-15 weeks).

    Items on the 14-item Warwick-Edinburgh Mental Well-Being Scale are self-reported over the past two weeks. There are 14 items with 5 response categories (1=none of the time; 5=all of the time), summed to provide a single score ranging from 14-70. A higher score indicates higher perceived mental well-being.

  2. Difference Between Intervention and Control Groups in Mean Mental Well-being Scores by Warwick-Edinburgh Mental Well-Being Scale at 16 Weeks Post-intervention (26-31 Weeks)

    Time frame: 16 weeks post-intervention (26-31 weeks).

    Items on the 14-item Warwick-Edinburgh Mental Well-Being Scale are self-reported over the past two weeks. There are 14 items with 5 response categories (1=none of the time; 5=all of the time), summed to provide a single score ranging from 14-70. A higher score indicates higher perceived mental well-being.

  3. Difference Between Intervention and Control Groups in Mean Sense of Community by the Brief Sense of Community Scale Immediately Post-intervention (10-15 Weeks)

    Time frame: post-intervention (10-15 weeks).

    Items on the 8-item Brief Sense of Community Scale are self-reported in which each item is scored using a Likert Scale of 1 (strongly disagree) to 5 (strongly agree). Scores can range from 8-40. A higher score indicates a stronger sense of community.

  4. Difference Between Intervention and Control Groups in Mean Sense of Community by the Brief Sense of Community Scale at 16 Weeks Post-intervention (26-31 Weeks)

    Time frame: 16 weeks post-intervention (26-31 weeks).

    Items on the 8-item Brief Sense of Community Scale are self-reported in which each item is scored using a Likert Scale of 1 (strongly disagree) to 5 (strongly agree). Scores can range from 8-40. A higher score indicates a stronger sense of community.

  5. Difference Between Intervention and Control Groups in the Odds of Experiencing Household Food Insecurity Immediately Post-intervention (10-15 Weeks)

    Time frame: post-intervention (10-15 weeks).

    Difference between intervention and control groups in the odds of experiencing household food insecurity immediately post-intervention (10-15 weeks). Items on the 18-item Household Food Security Survey Module are self-reported in relation to experiences in the past month.

  6. Difference Between Intervention and Control Groups in the Odds of Experiencing Household Food Insecurity at 16 Weeks Post-intervention (26-31 Weeks)

    Time frame: 16 weeks post-intervention (26-31 weeks).

    Difference between intervention and control groups in the odds of experiencing household food insecurity at 16 weeks post-intervention (26-31 weeks). Items on the 18-item Household Food Security Survey Module are self-reported in relation to experiences in the past month.

  7. Difference Between Intervention and Control Groups in the Odds of Malnutrition by Malnutrition Universal Screening Tool Immediately Post-intervention (10-15 Weeks)

    Time frame: post-intervention (10-15 weeks).

    Items on the Malnutrition Universal Screening Tool are self-reported and based on BMI (scored as 0= >20, 1= 18.5-20, 2 = <18.5) and percent of unplanned weight loss in the past 3-4 months (scored as 0 = <5%, 1 = 5-10%, 2 = >10%). Overall risk of malnutrition will be scored as 0=low risk, 1= medium risk, and >= 2= high risk.

  8. Difference Between Intervention and Control Groups in the Odds of Malnutrition by Malnutrition Universal Screening Tool at 16 Weeks Post-intervention (26-31 Weeks)

    Time frame: 16 weeks post-intervention (26-31 weeks).

    Items on the Malnutrition Universal Screening Tool are self-reported and based on BMI (scored as 0= >20, 1= 18.5-20, 2 = <18.5) and percent of unplanned weight loss in the past 3-4 months (scored as 0 = <5%, 1 = 5-10%, 2 = >10%). Overall risk of malnutrition will be scored as 0=low risk, 1= medium risk, and >= 2= high risk.

  9. Difference Between Intervention and Control Groups in Mean Diet Quality Subscores by Healthy Eating Index-2015 Immediately Post-intervention (10-15 Weeks)

    Time frame: post-intervention (10-15 weeks).

    Healthy Eating Index (HEI)-2015 scores are calculated from 24-hour dietary recalls. HEI-2015 total scores can range from 0-100, with a higher score indicating a higher diet quality. HEI-2015 total scores are calculated by summing subscores for adequacy components (total fruits, whole fruits, total vegetables, greens and beans, whole grains, dairy, total protein foods, seafood and plant proteins, fatty acids) and moderation components (refined grains, sodium, added sugars, saturated fats). Possible subscale scores are as follows:

    Adequacy components (higher score indicates a higher intake):

    Total vegetables (0-5) Greens and beans (0-5) Total fruits (0-5) Whole fruits (0-5) Whole grains (0-10) Dairy (0-10) Total protein foods (0-5) Seafood and plant proteins (0-5) Fatty acids (0-10)

    Moderation components (higher score indicates a lower intake) Sodium (0-10) Refined grains (0-10) Saturated fats (0-10) Added sugars (0-10)

  10. Difference Between Intervention and Control Groups in Mean Diet Quality Subscores by Healthy Eating Index-2015 at 16 Weeks Post-intervention (26-31 Weeks)

    Time frame: 16 weeks post-intervention (26-31 weeks).

    Healthy Eating Index (HEI)-2015 scores are calculated from 24-hour dietary recalls. HEI-2015 total scores can range from 0-100, with a higher score indicating a higher diet quality. HEI-2015 total scores are calculated by summing subscores for adequacy components (total fruits, whole fruits, total vegetables, greens and beans, whole grains, dairy, total protein foods, seafood and plant proteins, fatty acids) and moderation components (refined grains, sodium, added sugars, saturated fats). Possible subscale scores are as follows:

    Adequacy components (higher score indicates a higher intake):

    Total vegetables (0-5) Greens and beans (0-5) Total fruits (0-5) Whole fruits (0-5) Whole grains (0-10) Dairy (0-10) Total protein foods (0-5) Seafood and plant proteins (0-5) Fatty acids (0-10)

    Moderation components (higher score indicates a lower intake) Sodium (0-10) Refined grains (0-10) Saturated fats (0-10) Added sugars (0-10)

  11. Difference Between Intervention and Control Groups in the Risk of Experiencing Marginal, Moderate, or Severe Household Food Insecurity Immediately Post-intervention (10-15 Weeks)

    Time frame: post-intervention (10-15 weeks).

    Difference between intervention and control groups in the risk of experiencing marginal, moderate, or severe household food insecurity (relative to being food secure) immediately post-intervention (10-15 weeks). Items on the 18-item Household Food Security Survey Module are self-reported in relation to experiences in the past month.

  12. Difference Between Intervention and Control Groups in the Risk of Experiencing Marginal, Moderate, or Severe Household Food Insecurity at 16 Weeks Post-intervention (26-31 Weeks)

    Time frame: 16 weeks post-intervention (26-31 weeks).

    Difference between intervention and control groups in the risk of experiencing marginal, moderate, or severe household food insecurity (relative to being food secure) at 16 weeks post-intervention (26-31 weeks). Items on the 18-item Household Food Security Survey Module are self-reported in relation to experiences in the past month.

  13. Difference Between Intervention and Control Groups in the Risk of Being at a Medium or High Risk of Malnutrition by Malnutrition Universal Screening Tool Immediately Post-intervention (10-15 Weeks)

    Time frame: post-intervention (10-15 weeks).

    Difference between intervention and control groups in the risk of being at a medium or high risk of malnutrition (relative to being at low risk of malnutrition) by Malnutrition Universal Screening Tool immediately post-intervention (10-15 weeks). Items on the Malnutrition Universal Screening Tool are self-reported and based on BMI (scored as 0= >20, 1= 18.5-20, 2 = <18.5) and percent of unplanned weight loss in the past 3-4 months (scored as 0 = <5%, 1 = 5-10%, 2 = >10%). Overall risk of malnutrition was scored as 0=low risk, 1= medium risk, and >= 2= high risk.

  14. Difference Between Intervention and Control Groups in the Risk of Being at a Medium or High Risk of Malnutrition by Malnutrition Universal Screening Tool at 16 Weeks Post-intervention (26-31 Weeks)

    Time frame: 16 weeks post-intervention (26-31 weeks).

    Difference between intervention and control groups in the risk of being at a medium or high risk of malnutrition (relative to being at low risk of malnutrition) by Malnutrition Universal Screening Tool at 16 weeks post-intervention (26-31 weeks). Items on the Malnutrition Universal Screening Tool are self-reported and based on BMI (scored as 0= >20, 1= 18.5-20, 2 = <18.5) and percent of unplanned weight loss in the past 3-4 months (scored as 0 = <5%, 1 = 5-10%, 2 = >10%). Overall risk of malnutrition was scored as 0=low risk, 1= medium risk, and >= 2= high risk.

Other outcomes

  1. Difference Between Intervention and Control Groups in Mean Subjective Social Status by the MacArthur Scale of Subjective Social Status Community Ladder Immediately Post-intervention (10-15 Weeks)

    Time frame: post-intervention (10-15 weeks).

    The MacArthur Scale of Subjective Social Status community ladder consists of a self-reported visual analog scale, whereby respondents place themselves on a ladder rung according to their perceived social standing relative to others in their community. Responses can take a value from 1-10, with a higher score indicating higher perceived social status in relation to others' within ones' community.

  2. Difference Between Intervention and Control Groups in Mean Subjective Social Status by the MacArthur Scale of Subjective Social Status Community Ladder at 16 Weeks Post-intervention (26-31 Weeks)

    Time frame: 16 weeks post-intervention (26-31 weeks)

    The MacArthur Scale of Subjective Social Status community ladder consists of a self-reported visual analog scale, whereby respondents place themselves on a ladder rung according to their perceived social standing relative to others in their community. Responses can take a value from 1-10, with a higher score indicating higher perceived social status in relation to others' within ones' community.

  3. Subgroup Analysis for Impact of Intervention on Overall Diet Quality (Assessed by Healthy Eating Index-2015) by Sex Immediately Post-intervention (10-15 Weeks)

    Time frame: post-intervention (10-15 weeks)

    Subgroup analysis for impact of intervention on overall diet quality (assessed by Healthy Eating Index-2015) by self-reported sex immediately post-intervention (10-15 weeks). Healthy Eating Index (HEI)-2015 scores are calculated from 24-hour dietary recalls. HEI-2015 total scores can range from 0-100, with a higher score indicating a higher diet quality. HEI-2015 total scores are calculated by summing subscores for adequacy components (total fruits, whole fruits, total vegetables, greens and beans, whole grains, dairy, total protein foods, seafood and plant proteins, fatty acids) and moderation components (refined grains, sodium, added sugars, saturated fats). Adequacy and moderation components are each scored from 0-5, except for whole grains, dairy, and fatty acids, which are each scored from 0-10. For adequacy components, a higher score indicates a higher intake, whereas, for moderation components, a higher score indicates a lower intake.

  4. Subgroup Analysis for Impact of Intervention on Overall Diet Quality (Assessed by Healthy Eating Index-2015) by Age Immediately Post-intervention (10-15 Weeks)

    Time frame: post-intervention (10-15 weeks)

    Subgroup analysis for impact of intervention on overall diet quality (assessed by Healthy Eating Index-2015) by self-reported age immediately post-intervention (10-15 weeks). Healthy Eating Index (HEI)-2015 scores are calculated from 24-hour dietary recalls. HEI-2015 total scores can range from 0-100, with a higher score indicating a higher diet quality. HEI-2015 total scores are calculated by summing subscores for adequacy components (total fruits, whole fruits, total vegetables, greens and beans, whole grains, dairy, total protein foods, seafood and plant proteins, fatty acids) and moderation components (refined grains, sodium, added sugars, saturated fats). Adequacy and moderation components are each scored from 0-5, except for whole grains, dairy, and fatty acids, which are each scored from 0-10. For adequacy components, a higher score indicates a higher intake, whereas, for moderation components, a higher score indicates a lower intake.

  5. Subgroup Analysis for Impact of Intervention on Overall Diet Quality (Assessed by Healthy Eating Index-2015) by Sex at 16 Weeks Post-intervention (26-31 Weeks)

    Time frame: 16 weeks post-intervention (26-31 weeks)

    Subgroup analysis for impact of intervention on overall diet quality (assessed by Healthy Eating Index-2015) by self-reported sex at 16 weeks post-intervention (26-31 weeks). Healthy Eating Index-2015 scores are calculated from 24-hour dietary recalls.

  6. Subgroup Analysis for Impact of Intervention on Overall Diet Quality (Assessed by Healthy Eating Index-2015) by Age at 16 Weeks Post-intervention (26-31 Weeks)

    Time frame: 16 weeks post-intervention (26-31 weeks)

    Subgroup analysis for impact of intervention on overall diet quality (assessed by Healthy Eating Index-2015) by self-reported age at 16 weeks post-intervention (26-31 weeks). Healthy Eating Index-2015 scores are calculated from 24-hour dietary recalls.

  7. Frequency of Purchasing Food in Farmers' Markets

    Time frame: post-intervention (10-15 weeks)

    Self-reported frequency of purchasing food in farmers' markets. "How often did you buy food at a farmers' market (using coupons or money)?"

  8. Frequency of Money Spent at Farmers' Markets at Post-intervention (Excluding Coupons)

    Time frame: post-intervention (10-15 weeks)

    Self-reported frequency of money spent at farmers' markets (excluding coupons) among participants who reported purchasing foods from farmers' markets. "How often did you spend household money at a farmers' market? Do not include items you bought with coupons (if applicable)."

  9. Amount of Money Spent at Farmers' Markets

    Time frame: post-intervention (10-15 weeks)

    Self-reported amount of money spent at farmers' markets using coupons and own money

  10. Objective Data (From Coupons) on Foods Purchased Using Coupons at Farmers' Markets

    Time frame: Assessed at post-intervention (10-15 weeks)

    Number of coupons redeemed to purchase vegetables, fruit, meat and fish, eggs, dairy, cut herbs, and nuts.

  11. Foods Purchased at Farmers' Markets Using Own Money (Excluding Coupons)

    Time frame: Assessed at post-intervention (10-15 weeks)

    Self-Reported Foods Purchased at Farmers' Markets using own money (excluding coupons).

  12. Nutrition Skill-building Activity Attendance

    Time frame: Assessed at post-intervention (10-15 weeks)

    Self-reported data on attendance to nutrition skill-building activities ("Did you go to nutrition skill building activities offered by your community partner?")

Sponsors and collaborators

Lead sponsor

University of Calgary

Other

Collaborators

  • British Columbia Farmers' Market Nutrition Coupon Program
  • Canadian Institutes of Health Research (CIHR)

Registry information

Official study title

Impact of a Farmers' Market Nutrition Coupon Program on Diet Quality and Psychosocial Well-being Among Low-income Adults: A Randomized Controlled Trial

Important dates

Study start
2019
Primary completion
2020
Study completion
2020
First posted
May 16, 2019
Registry last updated
Dec 16, 2024

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

Related clinical trials

Published trials that share one or more normalized conditions with this study.