Member profile
Dr. Susan Horton
Organization:
University of Waterloo
Country:
Canada
Field(s) of expertise:
I am working on:
Economics of unhealthy diets
I am Emeritus Professor of Global Health Economics at University of Waterloo. I have worked on cost-effectiveness of various types of health interventions, and costing packages of interventions. Topics I have worked on include nutrition (particularly maternal and child nutrition), adolescents, micronutrients, unhealthy diets, diagnostics, cancer.
Dr. Susan Horton
Please see a proposed contribution on "Estimating the Hidden Costs of Unhealthy Diets: A Country Case Study."
SOFA Box Proposal: Estimating the Hidden Costs of Unhealthy Diets: A Country Case Study.
Felipe Dizon (World Bank), Patrizia Fracassi (FAO), Giles Hanley-Cook (Consultant, FAO), Susan Horton (Consultant, FAO), Kyoko Shibata Okamura (World Bank)
Current efforts to quantify the hidden economic costs of unhealthy diets (FOLU, 2019a; FAO, 2023) are galvanizing policy makers to act, in view of the global scale of the problem. FOLU (2019a) estimated the hidden costs of undernutrition as $1.8 trillion in 2018 (1.4% of global GDP, calculations using international dollars), and of obesity as $2.7 trillion (2.0% of global GDP). FAO (2023) used a similar methodology to derive national estimates for 154 countries. These large and shocking numbers have helped turn attention towards the potential role of agrifood systems policies, as a complement to contemporary public health policies.
Recognizing the complexity of covering all dimensions of hidden economic costs, our contribution proposes a country-level methodology to estimate the attributable risk of unhealthy diets for suboptimal nutritional status (e.g., overweight and obesity) and health outcomes (e.g., type II diabetes).
Our methodology addresses some of the recognized limitations and simplifying assumptions of FOLU (2019a) and FAO (2023). FOLU (2019b) note that “This analysis does not adopt a strict economic definition of externalities, but instead includes more broadly the top sources of lost value or of human and social costs related to global food and land use systems … As a result, this exercise provides a reasonably reliable indicative measure of the order of magnitude of hidden costs, but not in any way a conclusive answer. A key aim is to inform debate on this subject and inspire future research” (p14). Both FOLU (2019a) and FAO (2023) rely heavily on the IHME’s estimates of health impacts. Questions have been raised about the robustness of the IHME estimates at country level in view of significant changes between analyses using 2017 and 2019 data (Stanton et al, 2022), about the reliability of the country-level dietary data given the substantial data gaps requiring somewhat opaque interpolation (Beal et al (2021), about the unknown amount of double-counting when aggregating across multiple dietary risks, and about whether the estimates control appropriately for obesity separately from individual diet components (Horton et al, 2024).
Ongoing joint work between the World Bank and FAO aims to provide a more robust methodology which can be used at country level (Horton et al, 2024), building on the policy momentum generated by the global estimates, and taking up FOLU’s (2019b) exhortation for debate and further research. The work starts from the premise that one should not conflate malnutrition (in all its forms) with unhealthy diets. Although inadequate nutrient intakes is a key driver of undernutrition (here meaning child stunting and child wasting), one cannot forget the important role of infections and diseases. Hence improving water and sanitation (for example) must be considered along with diet in policies to reduce stunting (Mbuya et al). Similarly, one cannot assume that all individuals with a healthy weight have healthy diets: they may consume inadequate amounts of micronutrients and excessive amounts of salt and other dietary factors associated with higher risk of non-communicable diseases (NCDs). Finally, dietary intervention alone may not suffice to move overweight and obese individuals into the healthy weight category, especially in the absence of important confounding factors like healthy lifestyle behaviours.
This new project proposes to build on recently-developed, holistic, healthy diets metrics which aim to assess NCD risk at-scale. In particular we plan to use the two sub-metrics of the Global Diet Quality Score (GDQS) (Bromage et al, 2021). The GDQS is based on semi-quantitative diet recall data. The overall score is based on 25 food groups, 16 of which are considered to promote health, 7 of which are associated with increased NCD risk, and 2 of which when consumed in excess are associated with increased NCD risk.
We plan to use the new generation of combined nutrition and health surveys being collected in low- and middle-income countries, similar to surveys initiated in the high-income countries as obesity rates started to climb. These surveys contain (quantitative) dietary intake data, anthropometric data and selected NCD risk data (such as hypertension and fasting blood glucose). We expect this will allow us to estimate the health risks and economic costs associated with those individuals with healthy weights but unhealthy diets, and similarly to differentiate the health risks among overweight and obese individuals according to how healthy or unhealthy their diets are. This is an improvement over conflating weight status with healthy diets and allows policy to be better targeted through an increased understanding of risks associated with context-specific dietary patterns.
We are aiming to start work in the Philippines, a country where the “double burden” of malnutrition features prominently. A summary article using the 2013 National Nutrition Survey noted that one in ten adults has chronic energy insufficiency while three in ten are overweight or obese, and 70-80% of the population do not meet their needs for key micronutrients (Angeles-Agdeppa et al, 2019).
Estimates of the associated economic costs of malnutrition in all its forms vary considerably. FAO (2023) estimates the cost of the burden of disease (undernourishment) as 0.02% of GDP in 2020 but this excludes future productivity losses associated with losses in educational attainment and premature mortality. Mbuya et al (2021) include these additional losses, and their estimate is a loss of 1.5% of GDP in 2015. FAO (2023) estimates the cost of the burden of disease from dietary patterns (obesity and NCDs) as 6.8% of GDP in 2020, reflecting the use of IHME’s estimates of health impacts.
We anticipate that applying the proposed new methodology to nationally-representative data from the Philippines will provide useful estimates of the effect of diet quality on cost. The aim is that this analysis can inform national agrifood systems discussions. One concrete objective is to analyze whether existing public agricultural funding can be reoriented so as to support policy coherence in the agrifood and health sectors.
References:
Angeles-Agdeppa I, Sun Y, Denney L, Tanda KV, Octavio RAD, Carriquiry A, Capanzana MV. Food sources, energy and nutrient intakes of adults: 2013 Philippines National Nutrition Survey. (2019) 18:59 https://doi.org/10.1186/s12937-019-0481-z
Beal T, Herforth A, Sundberg S, Hess SY, Neufeld LM, 2021. Differences in modelled estimates of global dietary intake. Lancet 397 (10286): 1708-9. https://doi.org/10.1016/S0140-6736(21)00714-5
Bromage S, Batis C, Bhupathiraju SN, Fawzi WW, Fung TT, Li Y, Deitchler M, et al. Development and Validation of a Novel Food-Based Global Diet Quality Score (GDQS). J Nutr. 2021 Oct 23;151(12 Suppl 2):75S-92S. https://doi: 10.1093/jn/nxab244
FAO. 2023. The State of Food and Agriculture 2023 – Revealing the true cost of food to transform agrifood systems. Rome. https://doi.org/10.4060/cc7724en
Food and Land Use Coalition (FOLU), The. Growing Better. 2019a. https://www.foodandlandusecoalition.org/global-report/
---------. 2019b. Growing Better: Technical Annex. https://www.foodandlandusecoalition.org/wp-content/uploads/2019/09/FOLU-GrowingBetter-TechnicalAnnex.pdf
Horton S, Fracassi P, Siekmans K, Kato T, Hanley-Cook G. Estimating economic costs of unhealthy diets: a proposed methodology. World Bank Policy Research Working Paper 10671, January 2024. https://documents.worldbank.org/en/publication/documents-reports/documentdetail/099839401162431298/idu152ca6b541085314ca41a22a1bf67750bec89
Mbuya NVN, Demombynes G, Piza SFA, Adona, AJV. 2021. Undernutrition in the Philippines: Scale, Scope, and Opportunities for Nutrition Policy and Programming. International Development in Focus. Washington, DC: World Bank. http://hdl.handle.net/10986/35530
Skoufias E, Vinha K, Sato R. 2019. All Hands on Deck: Reducing Stunting through Multisectoral Efforts in Sub-Saharan Africa. Africa Development Forum series. Washington, DC: World Bank. doi:10.1596/978-1-4648-1396-2
Stanton AV, Leroy F, Elliott C, Mann N, Wall P, De Smet S. 2022. 36-Fold higher estimate of deaths attributable to red meat intake in GBD 2019: Is this reliable? Lancet 399 (10332): e23–26. https://doi.org/10.1016/S0140-6736(22)00311-7.