Long-Term Double Fortified Salt Usage for Child Health in Rural Bihar

Last registered on July 29, 2021


Trial Information

General Information

Long-Term Double Fortified Salt Usage for Child Health in Rural Bihar
Initial registration date
November 23, 2020

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 23, 2020, 10:31 AM EST

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

Last updated
July 29, 2021, 3:29 AM EDT

Last updated is the most recent time when changes to the trial's registration were published.



Primary Investigator

University of Göttingen

Other Primary Investigator(s)

PI Affiliation
University of Göttingen
PI Affiliation
Sam Houston State University
PI Affiliation
University of Göttingen

Additional Trial Information

Start date
End date
Secondary IDs
Many existing nutrition interventions evaluate the short-term effects on child health focusing on whether treatment matters for child health. To what degree timing and duration of exposure to a long-term nutrition intervention matter for child development is hardly considered. We want to provide evidence by examining the effectiveness of a hardly implemented government directive in India that postulates all government run schools to improve children’s diets by using iron and iodine fortified salt called double-fortified salt [DFS] in the school feeding program. Facilitating the availability of DFS at 107 randomly selected governmental schools in two blocks of the district Jehanabad in the state of Bihar, India, we want to examine how timing and duration of the use of DFS effect child health, cognition, and school outcomes. We contribute to the literature by considering one of the longest treatment periods of DFS in a school feeding program so far almost 4 years. Due to variation in onset and duration of DFS treatment, we include four exposure groups in our study to examine the effectiveness of DFS across different treatment periods. Further, we observe how a childhood intervention unfolds in outcomes for young adolescents. Using three waves of panel data of about 1,000 school children, we analyze the difference in means of the health, cognition, and education outcome variables of four exposure groups.
The results have high policy relevance as they show the potential of fortified foods in school feeding programs without crowding out other interventions.
External Link(s)

Registration Citation

Kumar, Abhijeet et al. 2021. "Long-Term Double Fortified Salt Usage for Child Health in Rural Bihar." AEA RCT Registry. July 29. https://doi.org/10.1257/rct.6800-2.0
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Experimental Details


We build on the RCT supplying DFS for the Indian MDM by Krämer et al. (2020) in the district Jehanabad in the state of Bihar, India. We established a supply chain of double fortified salt [DFS], salt fortified with iron and iodine, for preparing the decentralized school lunch in up to 107 government led primary schools [PS] and middle schools [MS].
Intervention Start Date
Intervention End Date

Primary Outcomes

Primary Outcomes (end points)
Hemoglobin and anemia status
Primary Outcomes (explanation)
Hemoglobin (Hb) assessments is a reliable indicator to screen individuals for anemia, to draw inferences about the iron status of populations and to evaluate responses to nutritional interventions. To check the hemoglobin level we propose to use the “HemoCue Hb Photometer”. The HemoCue® Hb photometer has been widely used for these purposes in recent years because it is portable, requires only a small sample of capillary or venous blood, is relatively inexpensive and simple to use. It does not require access to refrigeration or even electricity, and gives immediate, digitally displayed results. The hemoglobin level can be tested on site.
The HemoCue® B-Hemoglobin system (HemoCue AB, Ängelholm, Sweden) consists of disposable microcuvettes containing reagent in a dry form and a single purpose designed photometer. Hemoglobin measurements using the HemoCue system will involve collecting a drop of finger-prick blood using a sterile lancet and a microcuvette. Undiluted blood is placed directly into a microcuvette where the hemoglobin is converted to haemiglobinazide. The microcuvette is inserted into the photometer and the machine provides a direct readout of the haemoglobin result within 14 to 45 seconds. Certified medical staff will draw the blood samples.

According to a WHO classification for children between 5 and 11 years, severe anemia is defined by a hemoglobin concentration of less than 8.0 g/dl, moderate anemia by a hemoglobin concentration of 8.0 to 10.9 g/dl and mild anemia by a hemoglobin concentration of 11.0 to 11.4 g/dl. A hemoglobin concentration of 11.5 g/dl and above is considered non-anemic (WHO, 2011). Most anemia cases in our setting are likely to be chronic cases that are due to malnutrition and iron deficiency.

Secondary Outcomes

Secondary Outcomes (end points)
cognition test outcomes, educational outcomes
Secondary Outcomes (explanation)
We conduct four different cognition tests:

1. Digit span forward:
The forward digit-span assesses short-term auditory memory and simple verbal expression53. It is the only test that does not directly involve executive functions. The child is asked to repeat a series of numbers immediately after the enumerator red the series out. The number of digits is continuously increased and the longest list of numbers the child could remember was defined as the digit-span. The test is the same as in Malin’s Intelligence Scale for Indian Children.

2. Digit span backward:
The backward digit-span test measures the ability to store, use and manipulate new information. Backward digit-span also involves attention, impulse control and shifting from a forward to backward sequence. All of these abilities are commonly considered to be a part of the group of executive functions53–55. The administration of the backward digit-span test is the same as in forward digit-span test; however, the child is requested to repeat the digit sequence in its reverse order. The test is the same as in Malin’s Intelligence Scale for Indian Children.

3. Block Design:
The Block design test assesses planning and organizing56. In this test, children are asked to arrange red and white colored blocks in a way that they match a pattern of a picture. Children receive two points if they correctly arranged the blocks on the first try, one point, if they correctly arranged the blocks on the second try, after the test administrator had shown the correct solution to the child, and zero otherwise. They were asked to arrange four different pictures in the baseline survey that increased in difficulty. To account for a general increase in cognitive ability at the endline survey, two more pictures were added. The test is the same version as in Malin’s Intelligence Scale for Indian Children.

4. Colored Progressive Matrices
We use an abbreviated version of Raven’s Colored Progressive Matrices (RCPM)57 that measures abstract reasoning and the capacity to simultaneously solve several problems involving new information58. There is some evidence that the RCPM test measures executive functions59,60.18 We use six matrices from set A and six matrices from set AB. In this test, the child is shown an array of pictures with one missing box. Out of the six options, they are to select the picture that fits the missing box. The pictures progressively increase in complexity and abstraction. We score each correct answer with one point, hence the scale for RCPM ranges from 0 to 12. The RCPM are designed for children between 5 and 11 years old.

5. Stroop test:
The Stroop-like day-and-night test (Gerstadt et al. 1994) assesses the ability of inhibition (suppressing a habitual response), which is also considered to be a classical executive function (Anderson 2001, Carlson 2005). We used an extended version of this test, where six pairs of cards, which show pictures of opposites (day–night, boy–girl, large–small, up–down, warm-cold and young-old), were presented to the child. After shuffling the pictures, they were presented to the child one after the other and the child was asked to say the opposite of what they were seeing on the card. The scale for the day-and-night test ranges from 0 to 12. Initial errors that were self-corrected by the child were scored as a half point. Apart from inhibition, this test also requires memorizing two rules simultaneously. First, what the picture on the cards represent and second, to always say the opposite.
The Stroop like “Day-Night” test by Gerstadt et al. (1994) used in the first two survey waves to measure the ability of inhibition control is no longer appropriate for the new age group of the children in the endline. That is why, we use an adapted version of the fruit/vegetable Stroop by Röthlisberger et al. (2010). This test has been conducted with the help of the Institute for Psychology, University of Hildesheim.

For educational outcomes we measured scores in a reading and math test and attendance. For examining the reading and math skills the Annual Status of Education Report [ASER] reading assessment tool and the ASER Math tool are used that are developed by the Indian Non-Governmental Organization Pratham (ASER Centre, 2014). However, the conduction of the test has been modified to accommodate the setting.
School attendance is recorded from the official record books of the schools. The focus lies in particular on the past 12 months before the survey. The official records of many schools go only back for 12 months or to the start of the school year. The baseline includes attendance data for the time between November 2013 and October 2014, the midline for time between August 2015 and July 2016, and the endline for the time between January and December 2018. We calculate school attendance as the rate of the total number of days present of a child and the total number of days school is open for each time period.

For the analysis all secondary outcomes are normalized.

Experimental Design

Experimental Design
We sold DFS to 54 randomly selected public schools in Bihar, India, since 2015 and 53 more since 2017. DFS was sold to headmasters to a subsidized price of Rs. 12 (0.18 USD). The DFS was used to prepare the lunch at the school level. We received DFS directly from manufacturers. Only the headmasters and cooks were aware of the intervention. The start of DFS delivery is one source of variation. The other one is the inclusion of both PS and MS in our sample. Children in fifth grade have to choose another school to continue their education if they have attended a PS before. Thus, four different exposure groups are established.
Experimental Design Details
We look at four different exposure groups varying in onset and duration of receiving DFS in the school lunch: a) children who receive DFS from third grade in 2015 onward, b) children who receive DFS from fifth grade in 2017 onward, c) children who receive DFS from third grad in 2015 to the end of fifth grade in 2018, and d) children who are hardly exposed. The longest treatment period is about four years, 48 months (from August 2015 to July 2019).
Randomization Method
Randomization of schools and children done in office by a computer.
Randomization Unit
school level
Was the treatment clustered?

Experiment Characteristics

Sample size: planned number of clusters
All different combinations of PS and MS schools serve as clusters (at least 107)
Sample size: planned number of observations
We initially sampled 2000 children (20 children on average per school). We try to follow up with all of them.
Sample size (or number of clusters) by treatment arms
54 schools with early start of exposure to DFS, 53 schools with late start of exposure to DFS, and additional MS without treatment
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)

Institutional Review Boards (IRBs)

IRB Name
University of Göttingen
IRB Approval Date
IRB Approval Number
IRB Name
University of Göttingen
IRB Approval Date
IRB Approval Number


Post Trial Information

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Is the intervention completed?
Intervention Completion Date
February 28, 2020, 12:00 +00:00
Data Collection Complete
Data Collection Completion Date
July 31, 2019, 12:00 +00:00
Final Sample Size: Number of Clusters (Unit of Randomization)
We still provided treatment for all 107 schools but in the final analytical sample only children of 85 schools of our original sample are included.
Was attrition correlated with treatment status?
Final Sample Size: Total Number of Observations
The pre-survey in 2014-5 contained 2,008 students. We have completed information on outcomes and covariates for the three data collection waves for 1,051 children for the health outcomes sample and 820 children for the cognition and education outcome sample.
Final Sample Size (or Number of Clusters) by Treatment Arms
In the final sample we had 43 treatment schools and 42 control schools.
Data Publication

Data Publication

Is public data available?

Program Files

Program Files
Reports, Papers & Other Materials

Relevant Paper(s)

Reports & Other Materials