Food Systems and Nutrition Evidence Gap Map

To address the challenge of malnutrition and food insecurity, decision-makers need to understand what evidence exists on various interventions. 3ie’s first living evidence gap map (EGM) includes the largest collection of high-quality research on food systems interventions in low- and middle-income countries. We regularly add studies to ensure the most up-to-date evidence is available to our users. Developed with support from Innovative Metrics for Agriculture and Nutrition Actions this EGM is commissioned by Germany’s Federal Ministry for Economic Cooperation and Development (BMZ) through Deutsche Gesellschaft für Internationale Zusammenarbeit's (GIZ) K4N program.


Food systems are crucial to achieving most of the 17 Sustainable Development Goals (SDGs), as well as multiple other goals and commitments, such as those on climate change. What we need is science-driven food transformation and research will continue to play a vital role in this. By providing an overview of the literature relating food systems interventions to food security and nutrition outcomes, 3ie aims to address the challenges of malnutrition and food insecurity in low- and middle-income countries. Our Food Systems and Nutrition Evidence Gap Map (EGM) shows where evidence is available and where new research is needed to fill evidence gaps regarding the impacts of food systems interventions.

Making sense of a vast and growing literature

As of January 2023, our EGM includes over 2,200 studies and presents a rich body of evidence, including the latest research, in the fast-growing field of food systems impact evaluations. It reports on evidence from all key areas and intervention types and identifies potential primary and synthesis evidence gaps. It is also a living EGM, which means new studies are added at regular intervals. Apart from adding studies, we also publish summaries of how the literature has changed, and provide insight if previous evidence gaps have been addressed. We are also leveraging it to produce a series of evidence synthesis products. We will be keeping the living EGM updated through March 2023.

Along with Innovative Methods and Metrics for Agriculture and Nutrition Actions (IMMANA), this EGM and the updates have been commissioned by Germany’s Federal Ministry for Economic Cooperation and Development (BMZ) through Deutsche Gesellschaft für Internationale Zusammenarbeit’s (GIZ) “Knowledge for Nutrition” program.

View living EGM | Read the brief and full report (original) | Read update #1 (Dec 2021), update #2 (Apr 2022), update #3 (Aug 2022) | update #4 (January 2023)

Latest findings

When the EGM was launched in 2021, a total of 2,035 studies were identified for inclusion—178 systematic reviews and 1,838 impact evaluations. There has been a rapid increase in the number of studies published since and the map has now been updated in four instances—reinforcing the need for a ‘living EGM’.

January 2023 update

In our latest update, we have added 72 new studies to the map. There continues to be a focus on the food supply chain (40 new studies), specifically the production system (46 new studies). However, there was no clear pattern in the types of production systems interventions considered, with the most commonly reported intervention being “other” improvements to the production system (9 new studies). There seems to be a growing focus on national and transnational interventions (14 new studies, 24%), which may be facilitated by an ongoing shift towards quasi-experimental research (32 new studies, 62%). Almost a third of these studies considered the impacts of the recent change in land rights and related programs in China. 

In the original EGM (covering January 2000 – September 2020), evaluations disproportionally considered supplement provision (20%); fortification (16%); direct food provision (11%); and peer support and counselling targeting consumer behaviour (7%). No or few evaluations assessed advertising regulations, food waste education programs, food packaging, governmental price manipulations, and interventions supporting women’s decision-making or measured women’s empowerment outcomes. 

Studies added to the EGM


Benefits of a living EGM

The process of continuously updating this map has allowed for the identification of ground-breaking evaluations in the field. We have seen work in areas with knowledge gaps, such as women’s empowerment; measures of diet insufficiency; national level policies; and economic, social, and political stability. This responds directly to a recent call from the European Commission for independent and up-to-date reports on the scientific evidence about food systems transformation to fill knowledge gaps in the field.

Extending the use of the living EGM

To fill some of the key gaps identified through the mapping process, 3ie produced two additional synthesis products: a rapid evidence assessment on the impact evaluations of women’s empowerment interventions included in the map and a systematic review on the use of fiscal policies to support a healthy diet. These synthesis products were produced in less than half the time of traditional systematic reviews because we were able to leverage the EGM. 

Evidence on women’s empowerment within the food systems 

Findings: There were ten impact evaluations of interventions to support women’s empowerment within the Food Systems and Nutrition Evidence Gap Map. Overall, these interventions generally had positive impacts on food security and food affordability and availability. Evidence from qualitative work suggests that women’s empowerment interventions best influenced nutritional outcomes when adopting gender-transformative approaches and addressing gender and social norms.  

Implications: Policy-makers should consider improving women’s social capital so they can better control and decide how to feed their families. Qualitative evidence suggests that multi-component interventions seem to be more sustainable than single-focus interventions, especially when they combine a livelihoods component (asset transfer or financial services) with behavioural change communication. Researchers need to address issues with inconsistent data and reporting, particularly relating to seasonal changes, social norms and time taken between rounds of data collection in order to implement high-quality evaluations. Future studies could further contribute to the evidence base of gender-transformative approaches by carefully considering contextual norms and avoiding stereotyping women into pre-decided roles which may perpetuate social norms. 

Read the Brief

Evidence on taxes and subsidies to support a healthy diet

Findings: We identified 49 impact evaluations and two systematic reviews through an additional systematic search that extended beyond the Food Systems and Nutrition Evidence Gap Map. Unfortunately, these represented only 24 unique intervention-outcome-population combinations due to the repeated evaluation of the same taxes. We found that taxes on unhealthy foods may decrease the purchases of unhealthy foods, but this effect was driven by a single, high risk of bias study. Impacts on diet, health, and well-being were rarely considered, so conclusions could not be reached. However, we did find evidence that awareness of the health-based justifications for the taxes and the health consequences of consuming such foods may facilitate the impacts of these interventions.  

Implications: Tax and subsidy policies aimed at improving diets should incorporate information campaigns on health benefits and health risks associated with certain food and beverage consumption. For tax policies, exposure to health information may amplify the signalling effects of taxes and reduce avoidance behaviours, such as cross-border shopping. Future evaluations of fiscal policies should diversify data sources to better understand the impact on diet and health outcomes. Future research should also use evaluation design strategies that account for confounding and independence from other programs or events that may occur during the implementation period. 

Read the Brief

Watch our latest webinar on ‘Filling knowledge gaps to transform the food system’ which brought together experts from GIZ, EAT Forum, IFPRI, Bill & Melinda Gates Foundation, and Centre for Global Child Health. The panel focused on the experience in navigating the evidence base within the field, the types of evidence needed, and how the research community can better respond to the evidence needs of policymakers and implementers.

The effects of food systems interventions on food security and nutrition outcomes in LMICs

The devastating impacts of malnutrition and food insecurity are well documented. In low- and middle-income countries (L&MICs), constraints and complexities within food systems are significant drivers of these conditions. As a result, there has been a significant global focus on improving food systems to facilitate better food security and nutrition outcomes. The evidence base regarding the impact of interventions within food systems in achieving these aims is massive, but complicated and disorganized, making it difficult for donors, policymakers and practitioners to navigate. 3ie's Evidence Gap Map addresses this challenge.