Evaluation of a Letter Intervention Promoting a Plant-based Diet

Summary

The researchers' mission is to promote healthier eating behavior and to reduce costs associated with healthcare. The purpose of this study is to evaluate the effects of mailing randomly selected participants a letter promoting a plant-based diet. Depending on the experimental condition, participants may additionally receive a free documentary, Forks Over Knives, and they may also get letters which use commitment- or prevention-focused messages to encourage watching the documentary and changing their eating behavior. The researchers hypothesize that receiving the documentary will be associated with lower insurance claims and improved health outcomes one and two years later. The researchers also hypothesize that using either commitment- or prevention-focused messages will also contribute to lower insurance claims and improved health outcomes compared to experimental conditions where materials did not include these messages. This study will help the researchers design evidence-supported programs that can improve people's health.

Conditions

• Cardiovascular Diseases
• Diabetes Mellitus
• Obesity

Interventions

BEHAVIORAL

Personal testimonial

Participants will receive a letter promoting a plant-based diet. This letter will feature a personal testimonial about the benefits of a plant-based diet. Presenting this information to participants might encourage them to make behavioral changes to improve their health.

BEHAVIORAL

Forks Over Knives Documentary

Participants will be mailed the documentary Forks Over Knives, which provides scientific arguments promoting a plant-based and whole foods diet. The behavioral effect of this documentary comes from watching the documentary and potentially choosing to order a free cookbook (participants are given this opportunity in the letter accompanying the documentary). The effect of the diet itself is not a central part of the intervention, as people can choose to adopt or not adopt any part of the diet.

BEHAVIORAL

Commitment nudge

At the end of the letter promoting a plant-based diet, participants will be asked to write dates and personal signatures committing to watching the documentary. They will be asked to mail back this written commitment. Stating one's intentions to implement certain behavior is meant to increase the likelihood of follow-up behavior. This request might nudge more people to watch the documentary and make some behavioral changes to prevent negative health outcomes.

BEHAVIORAL

Prevention nudge

As part of the letter promoting a plant-based diet, one paragraph will describe the risks of not taking action. This phrasing reframes the status quo as contributing to future loss (e.g., costs of medication and operations). In effect, the letter encourages participants to focus on preventing this loss by taking action. This additional text might nudge more people to watch the documentary and make some behavioral changes to prevent negative health outcomes.

Sponsors & Collaborators

• Geisinger Clinic

  lead OTHER

Principal Investigators

• Amir Goren, PhD · Program Director

• Henri Carlo Y Santos, PhD · Post-doctoral Fellow

• Christopher Chabris, PhD · Professor

• Michelle N Meyer, PhD, JD · Assistant Professor

• Allison Hess, BS · Vice President

Study Design

Allocation

RANDOMIZED

Purpose

SUPPORTIVE_CARE

Masking

TRIPLE

Model

FACTORIAL

Eligibility

Min Age

18 Years

Sex

ALL

Healthy Volunteers

No

Timeline & Regulatory

Start

2019-06-20

Primary Completion

2020-06-30

Completion

2022-06-30

Countries

• United States

Study Locations