The use of double-fortified salt in school lunches reduced anaemia by 22–27% among schoolchildren aged 7 and 8 in Bihar, India

Anaemia is a global public health challenge that affects about 43% of children worldwide under the age of five. Redressing this problem is vital for human capital formation in developing countries, as anaemic children are less healthy, have lower cognitive abilities, attain lower education, and are less productive in labour markets (Currie and Vogl 2013).

The main cause of childhood anaemia in India is iron deficiency. A national survey shows that children receive only 2.4% of their diet's recommended daily iron intake, and the condition accounts for a significant proportion of daily deaths in the under-five age group (IIPS and ICF 2017). Consumption of iron-rich diets, iron supplements, iron-fortified wheat or rice, double-fortified salt (DFS, fortified with iron and iodine) or bio-fortified products can help reduce anaemia among children. 

Double-fortified salt (DFS) can reduce anaemia – if children actually consume it 

Vast evidence exists to show that DFS can reduce anaemia, but the evidence on the effectiveness of DFS programs at scale is limited. This is primarily because the salt may not, in fact, be reaching its intended consumers.

For example, Banerjee et al. (2018) show that market-based or free delivery of DFS has limited impacts on anaemia due to low take-up of DFS by households. Their findings imply that the choice of distribution channel is key in anaemia prevention. To ensure high and consistent compliance, a distribution channel must be designed that is simple, scalable and cost-effective, and has wide geographic and socioeconomic reach. 

School lunches as a key channel for DFS: An experiment in Bihar, India

We conducted a randomised controlled trial that provided DFS for use in the preparation of school lunches in primary schools in the state of Bihar, India (Krämer, Kumar and Vollmer 2021). Bihar is a relevant setting to examine this question as the state has limited capacity to deliver health services and continues to be at the bottom of all indicators of human development. The anaemia rate among children, at 58%, is one of the highest in the country. 

In contrast, the net enrolment rate at the primary level of 94% is above the national average, indicating widespread access to schools at the primary level. School lunches are delivered under the midday meal scheme, which is operational in 70,000 schools across the state and covers slightly more than 10 million children every day. This provides a unique setting to examine the effects of the DFS intervention on children’s health and learning outcomes.

The study conducted an experiment in two blocks of the Jehanabad district in Bihar. We supplied subsidised DFS for school-lunch preparation for one year to 54 randomly allocated treatment schools. The control schools continued to use non-DFS salt (mostly iodised salt). The evaluation sample included 2,000 grade II children selected from 107 primary schools. The baseline incidence of anaemia is 42%, and the average class size was 28 students. 

Using DFS in school lunches reduced the prevalence of anaemia

We evaluated the effects of the DFS intervention on haemoglobin levels, anaemia and cognitive performance of the children. Cognitive ability was measured by five different cognitive tests: forward digit-span, backward digit-span, block design, Stroop-like day-and-night test, and Raven’s coloured progressive matrices. Our results after a year-long intervention show that the use of DFS in the school lunch had the following effects:

  • Haemoglobin: The average heamoglobin level increased by 0.185 g/dL, or by 1.6%. 
  • Anaemia: The intervention reduced any form of anaemia by 9.9 percentage points or 22% and reduced mild anaemia by 5.3 percentage points or 27%, but had no impact on the prevalence of severe anaemia.
  • Cognitive performance: Despite the beneficial impacts on anaemia, the intervention on average had no significant impacts on cognitive outcomes or maths and reading test scores.  
  • Heterogenous impacts: The impacts on haemoglobin and anaemia at 90% attendance were almost double the effects at 70% attendance rate. The intervention also had significant impacts on maths and reading test scores at higher attendance levels. The intervention brought greater and statistically significant health improvements to girls compared to boys. We do not find evidence of heterogeneous effects by the baseline anaemic status of children. 

DFS is a highly cost-effective means to reduce anaemia

Our estimates show that the intervention was cost-effective, in terms of cost incurred per disability-adjusted life-years (DALYs) saved. Our intervention reached almost 14,000 children in 54 schools; because all children at a school benefited from it, and not only those that took part in the study, the cost per child was about $0.35. Our intervention averted one DALY at a cost of $280. The cost could potentially be reduced if delivered at scale.

The WHO assesses interventions as "very cost-effective" if the cost per DALY averted is less than the GNI per capita of the country where the intervention is going to be implemented. India’s GNI per capita at purchasing power parity in 2015 was US$6,030  (World Bank 2017), which means that our DFS intervention was very cost-effective. Our estimate is a conservative assessment of the cost-effectiveness of the intervention because it does not account for the potential long-term effects of the intervention on health, education and other forms of human capital. 

Policy implications: Using schools as a channel for delivering micro-nutrients

One of the most salient problems faced by developing countries is how to deliver health products or health services to vulnerable populations, particularly in a setting with inefficient delivery and low take-up of health programmes. In the case of DFS, market-based or free delivery had limited impacts on anaemia (Banerjee et al. 2018). Our study shows that policymakers can take advantage of the existing school-lunch programmes to deliver micronutrients to schoolchildren. 

The findings from this study show that school-based distribution of fortified products could be an effective channel in reducing iron deficiency among school children. Globally, about 380 million schoolchildren are served lunches daily. If these school lunches were to be fortified with DFS, the high rate of anaemia incidence in low-income countries could be reduced significantly. School-based supply of micronutrients is a low-cost, less burdensome and effective strategy to tackle malnutrition among children, especially for health products that suffer from low take-up.  


Banerjee, A, S Barnhardt and E Duflo (2018), “Can iron-fortified salt control anemia? Evidence from two experiments in rural Bihar”, Journal of Development Economics 133: 127–146.

Currie, J and T Vogl (2013), "Early-life health and adult circumstance in developing countries", Annual Review of Economics 5(1): 1-36.

IIPS and ICF (2017), National Family Health Survey (NFHS-4), 2015-16, International Institute for Population Sciences.

 Krämer, M, S Kumar and S Vollmer (2021), “Improving child health and cognition: Evidence from a school-based nutrition intervention in India”, The Review of Economics and Statistics 103(5): 818–834.

World Bank (2017), World Development Indicators.

Childhood anaemia Iron deficiency India Double-fortified salt Health intervention