Randomized Controlled Trial on How to Increase Fruit and Vegetable Intake among the Japanese Population

Last registered on July 19, 2023


Trial Information

General Information

Randomized Controlled Trial on How to Increase Fruit and Vegetable Intake among the Japanese Population
Initial registration date
July 14, 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
July 19, 2023, 2:32 PM EDT

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 for adults is about 280g, falling short of the 350g target. Continued inadequate vegetable intake increases the risk of lifestyle-related diseases such as hypertension, dyslipidemia, and arteriosclerosis. The purpose of this study is to implement a commitment intervention that will allow Japanese consumers to determine their target vegetable intake and to examine ways to increase vegetable intake.
The survey will measure the fruit and vegetable intake of approximately 2,000 civil servants working for Japan's Ministry of Agriculture, Forestry and Fisheries, and asking approximately 1,000 randomly selected participants from the measured population to fill in a target for fruit and vegetable intake one month later. They were then asked to measure their fruit and vegetable intake one month later to confirm changes in intake. Based on the results, we propose measures to increase fruit and vegetable intake in Japan.
To measure fruit and vegetable intake, we used a vegetable intake measuring instrument (Veggie Meter®, Longevity Link Corporation) (Redtke et al.), which can measure 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, https://doi.org/10.1093/cdn/nzab104
External Link(s)

Registration Citation

Tamaki, Shiho. 2023. "Randomized Controlled Trial on How to Increase Fruit and Vegetable Intake among the Japanese Population." AEA RCT Registry. July 19. https://doi.org/10.1257/rct.11775-1.0
Experimental Details


Intervention Start Date
Intervention End Date

Primary Outcomes

Primary Outcomes (end points)
This study will observe changes in participants’ fruit and vegetable intake. The outcome variable of interest is the carotenoid score as measured by a vegetable intake measurement device (Veggie Meter ®, Longevity Link Corporation) that can measure blood carotenoids in a non-contact manner. Carotenoids are bioactive phytochemicals found in various fruits and vegetables that cannot be synthesized de novo in humans and, therefore, are only obtained from the diet. The Veggie Meter® is a noninvasive research-grade instrument that detects and quantifies carotenoids in the skin.
Primary Outcomes (explanation)

Secondary Outcomes

Secondary Outcomes (end points)
Secondary Outcomes (explanation)

Experimental Design

Experimental Design
First, approximately 2,000 employees will be asked to measure their carotenoid score. Of those measured, 1,000 will be randomly selected as the intervention group and asked to enter a target value for their next carotenoid score. The control group will not receive a commitment intervention in which they are asked to enter their target values; after four weeks, approximately 1,000 people in the intervention group and 1,000 people in the control group will have their carotenoid scores measured to see how they change.
Experimental Design Details
Randomization Method
The subjects are assigned using the date of birth of the intake measurer. Subjects with odd-numbered birth dates will be assigned to the intervention group, and those with even-numbered birth dates will be assigned to the control group.
Randomization Unit
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 2,002 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