Promoting Adolescents' Healthy Food Choices through Social Media in Vietnam

The intervention involves two well-known Vietnamese influencers who will create content encouraging healthy eating, particularly focusing on fruit consumption. Participants will be randomly assigned to private virtual groups on Zalo, a popular communication app in Vietnam. Four groups will be formed: one control group and one intervention group for each influencer. The control groups will receive 4 standard influencer content, such as lifestyle, travel, and entertainment, while the intervention groups will receive 8 supplementary content promoting healthy eating.

The trial involves two well-known Vietnamese influencers, each with their respective audience divided into control and intervention groups. Participants, consisting of Vietnamese adolescents and young adults, will be recruited through Facebook posts shared by the influencers (KOLs) and school outreach. The control groups will receive 4 regular influencer posts (e.g., lifestyle, travel, entertainment), while the intervention groups will receive an additional 8 posts specifically promoting healthy eating habits, with a focus on fruit consumption. The healthy eating content includes:

i) Informational videos highlighting the benefits of fruit consumption,
ii) Practical tips on incorporating fruits into daily meals, and
iii) Engaging visuals of influencers enjoying fruits as snacks or part of their meals.

The intervention will run for 3 weeks, during which participants' engagement and exposure to the content will be closely monitored. A total of five online surveys will be conducted: one baseline survey before the intervention, three surveys distributed during the intervention, and one endline survey after the intervention is completed. These surveys will measure changes in participants' knowledge, attitudes, and behaviors toward healthy eating.

Group interactions on Zalo will be actively moderated by a research assistant to maintain participant engagement and ensure consistent exposure to the intervention content. The research assistant will also be responsible for sending online survey links to participants at each stage of the study.

2024-12-07

2024-12-23

Number of times participants consumed fruits from a pre-specified list in the past 24 hours.

The primary outcome will be measured using a food recall survey where participants self-report the times of the day they consumed any of the 10 fruits from our pre-determined list. Participants can report up to five time slots, corresponding to the three main meals (breakfast, lunch, dinner) and two snack times (morning and afternoon snacks).

Unhealthy food consumption: The number of times participants consumed a pre-specified list of unhealthy food items in the past 24 hours.
Nutritional knowledge: Participants' understanding of fruit nutritional content (e.g., Vitamin C, beta-carotene, and Vitamin A).
Attitudes toward healthy eating: Participants’ attitudes about fruit consumption and healthy eating habits.

Unhealthy food consumption: Participants will report their consumption of unhealthy snacks, including processed foods and sugary beverages, in the past 24 hours.

Nutritional knowledge: Four multiple-choice questions will assess participants' knowledge regarding fruits rich in Vitamin C, beta-carotene, and Vitamin A, as well as general dietary recommendations (e.g., recommended daily fruit intake). Example questions include: "Which fruits are rich in Vitamin C?"; "Which fruits have high content in beta-carotene?"

Attitudes: Four Likert-scale questions will assess participants’ attitudes toward fruit consumption and healthy eating habits. Examples include: "I am ready to substitute unhealthy snacks for fruits in my daily life"; "I have trouble choosing fruits when eating out or with friends"

This study is a randomized controlled trial designed to evaluate the impact of social media influencer marketing on healthier eating habits among Vietnamese adolescents. Participants will be recruited through Facebook and schools and will first complete an online recruitment survey to provide baseline information. Based on this survey, eligibility will be determined, with inclusion criteria being adolescents or young adults aged 13 to 24 years and residing in Vietnam. Eligible participants will be randomly assigned to one of four private virtual groups on Zalo, a popular communication app in Vietnam. Two well-known Vietnamese influencers will participate in the trial, each with one intervention group and one control group. Both control groups will receive regular influencer content such as lifestyle, travel, and entertainment, while the intervention groups will receive supplementary content promoting healthy eating, particularly emphasizing fruit consumption. The effects of the intervention will be measured through four online surveys distributed at different stages of the study. Participants will receive a phone card credit valued at $2.50 for each completed survey as an incentive to ensure engagement and high-quality responses.

The randomized controlled trial involves two key opinion leaders (KOLs), each with their audience randomly split into two groups: one control and one intervention group. Participants will be Vietnamese adolescents and young adults recruited via targeted Facebook posts shared by the KOLs and school outreach. Interested individuals will first complete an online recruitment survey to provide baseline information. Eligibility will be determined based on the following criteria: being an adolescent or young adult aged 13 to 24 years and residing in Vietnam.

Group Assignments:

Control Groups (2 groups, 1 per influencer): Participants will receive only regular influencer content, including posts and videos related to lifestyle, travel, and entertainment.
Intervention Groups (2 groups, 1 per influencer): Participants will receive both the regular influencer content and additional content promoting healthy eating. The healthy eating content includes:
i) Videos and posts encouraging fruit consumption.
ii) Information on the health benefits of fruits (e.g., Vitamin C, beta-carotene, and Vitamin A).
iii) Visuals showcasing influencers consuming fruits as snacks or part of meals.
Measurement and Surveys:
To measure the intervention's effects, participants will complete a total of five online surveys:

Baseline Survey: Conducted before group assignment to collect demographic and baseline information
Survey 1: After the first healthy content is shared
Survey 2: After the fourth healthy content is shared
Survey 3: After the sixth healthy content is shared
Endline Survey: After all eight healthy contents are shared.
Participants will receive a phone card credit valued at $2.50 for each completed survey as an incentive to maintain engagement and ensure high-quality responses. Those who successfully complete all four follow-up surveys will receive an additional $2.50 phone card credit. To further encourage participation, at each survey round, four participants will be randomly selected to receive a bonus phone card worth $2.50.

Study Duration:
The intervention will run for 4 weeks, during which group interactions will be monitored to ensure exposure and engagement. The five online surveys will assess primary and secondary outcomes, including fruit consumption frequency, unhealthy food consumption, nutritional knowledge, and attitudes toward healthy eating.

Randomization was conducted using the randomize command in Stata to achieve balance across five key covariates declared during the baseline (online) survey. These covariates, all based on self-declared data, include age, sex, province, intensity of social media use (the average number of hours spent per day), exposure to healthy food content on social media (how often participants see posts about healthy food or nutrition), and a proxy for social media influence on food practices (how likely participants are to try a new food or recipe after seeing it on social media).

The unit of randomization is at the individual level. Participants were divided into two separate pools, one for each influencer (KOL). Within each pool, participants were randomly assigned to either the control or intervention group for that specific influencer. In cases where participants responded to the baseline surveys for both influencers, a random selection process was conducted to determine to which influencer's pool they would be assigned. This approach ensures that each participant was included in only one group while maintaining balance across treatment and control groups, accounting for covariates.

No

Not applicable, as randomization was conducted at the individual level.

The planned number of observations is 300 participants, with each participant randomly assigned to one of four groups (two influencers, each with a control and intervention group).

The study includes 300 participants evenly distributed across the four treatment arms:
Influencer 1 – Control: 75 participants, Intervention: 75 participants
Influencer 2 – Control: 75 participants, Intervention: 75 participants

Based on a two-sample proportions test with the following parameters: Alpha (significance level): 0.05 Power: 0.80 Total sample size: 300 (150 per group) Baseline proportion (p1): 0.50 Effect size: 0.1591 (difference in proportions) Estimated experimental-group proportion (p2): 0.6591 This power calculation indicates that the study is powered to detect a 15.91 percentage point increase in the outcome of interest (e.g., fruit consumption) with 80% power at a 5% significance level.