Analysis of Randomized Controlled Trial to Increase Fruit and Vegetable Intake in the Japanese Population

Last registered on November 18, 2023


Trial Information

General Information

Analysis of Randomized Controlled Trial to Increase Fruit and Vegetable Intake in the Japanese Population
Initial registration date
November 13, 2023

Initial registration date is when the trial was registered.

It corresponds to when the registration was submitted to the Registry to be reviewed for publication.

First published
November 18, 2023, 6:13 PM EST

First published corresponds to when the trial was first made public on the Registry after being reviewed.



Primary Investigator

Policy Research Institute, Ministry of Agriculture, Forestrynand Fisheries

Other Primary Investigator(s)

Additional Trial Information

In development
Start date
End date
Secondary IDs
Prior work
This trial does not extend or rely on any prior RCTs.
In Japan, the per capita vegetable intake per adult is about 280g, falling short of the 350g target. Long-term inadequate vegetable intake increases the risk of lifestyle-related diseases, such as hypertension, dyslipidemia, and arteriosclerosis. This study will examine ways to increase vegetable intake by implementing a commitment intervention to have Japanese consumers set a vegetable intake target. The study will measure the fruit and vegetable intake of approximately 2,000 civil servants working at Japan's Ministry of Agriculture, Forestry, and Fisheries (MAFF). The authors will question approximately 1,000 randomly selected participants from the measured population to set a target for fruit and vegetable intake for the upcoming month. Next, they will be asked to measure their fruit and vegetable intake for that one month to confirm the changes in their intake. Based on the results, we will propose measures to increase fruit and vegetable intake in Japan. To measure fruit and vegetable intake, we will use a vegetable intake-measuring instrument (Veggie Meter®, Longevity Link Corporation) (Redtke et al.), which can measure the carotenoids in the blood without contact.
Marcela D Radtke, Mykaela Poe, Jodi Stookey, Stephanie Jilcott Pitts, Nancy E Moran, Matthew J Landry, Lewis P Rubin, Virginia C Stage, Rachel E Scherr(2021)Recommendations for the Use of the Veggie Meter® for Spectroscopy-Based Skin Carotenoid Measurements in the Research Setting, Current Developments in Nutrition, Volume 5, Issue 8, August 2021, nzab104,
External Link(s)

Registration Citation

Tamaki, Shiho. 2023. "Analysis of Randomized Controlled Trial to Increase Fruit and Vegetable Intake in the Japanese Population." AEA RCT Registry. November 18.
Experimental Details


To test the effectiveness of their commitment, the intervention group will be invited to set their next carotenoid score goal via email. They will then be able to enter their next target carotenoid score via the hyperlink in the email. The control group will not be asked to set a target carotenoid score and will not be informed of the hyperlink.
Intervention Start Date
Intervention End Date

Primary Outcomes

Primary Outcomes (end points)
 This study will observe changes in fruit and vegetable intake. The outcome variable of interest will include the carotenoid score measured using the vegetable intake measurement device (Veggie Meter ®, Longevity Link Corporation) that can measure blood carotenoids without contact. Carotenoids are bioactive phytochemicals found in a variety of fruits and vegetables and cannot be synthesized de novo in humans; therefore, these can be obtained only from food intake. The Veggie Meter® is a noninvasive research-grade instrument that will detect and quantify the carotenoids in the participants’ skin.
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
First, approximately 2,000 staff members will be asked to measure their carotenoid score. Among those who will be measured, approximately 1,000 will be randomly selected as the intervention group and asked to enter a target value for their next carotenoid score. After four weeks, the 1,000 participants in the intervention and control groups each, will be asked to measure their carotenoid score to observe the changes.
Experimental Design Details
Randomization Method
The authors will assign the subjects using the date of birth of the study participant. Subjects with odd-numbered dates of birth will be assigned to the intervention group and those with even-numbered ending dates of birth will be assigned to the control group.
Randomization Unit
 Individual
Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters
2 groups (intervention and control)
Sample size: planned number of observations
A total of 1,163 people were notified of the measurement guide.
Sample size (or number of clusters) by treatment arms
Approximately 1,001 participants in the intervention group and 1,001 participants in the control group
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)

Institutional Review Boards (IRBs)

IRB Name
Ethics Review Committee, National Institute of Agriculture, Forestry and Fisheries Policy
IRB Approval Date
IRB Approval Number


Post Trial Information

Study Withdrawal

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Is the intervention completed?
Data Collection Complete
Data Publication

Data Publication

Is public data available?

Program Files

Program Files
Reports, Papers & Other Materials

Relevant Paper(s)

Reports & Other Materials