William A. Masters, Yan Bai & Kate Schneider

1. Measuring the Cost of Nutritious Diets in Africa, South Asia and Worldwide: Are Healthy Foods Affordable? William A. Masters, Yan Bai & Kate Schneider Friedman School of Nutrition Science and Policy, Tufts University Slides for the Tufts University School of Medicine Global Health Seminar Series, 24 April 2019 This seminar presents work in progress from a project entitled Changing Access to Nutritious Diets in Africa and South Asia (CANDASA) funded by UKAid and the Bill & Melinda Gates Foundation. Details at: https://sites.tufts.edu/candasa.

2. Are changes in food environments makingnutritious diets more accessible, or further out of reach?

3. Changing Access to Nutritious Diets in Africa and South Asia (CANDASA) • Funded by UKAid and the Bill & Melinda Gates Foundation (OPP1182628), for their joint portfolio of ag-nutrition impact studies: https://www.anh-academy.org/dfid-bmgf-agriculture-nutrition-research-investments. • Launched Dec. 2017, runs through June 2020 • Implemented at Tufts and IFPRI (Washington, Delhi and Addis), with research partners in Ghana, Tanzania, and Malawi • All data, software tools and results are on the project website at http://sites.tufts.edu/candasa

4. Measuring the cost of nutritious diets motivation| methods | data | results | conclusion Existing food price indexes do not measure nutritional value Traded food commodity prices are weighted by trade volume World food prices, Jan 2015-Nov 2018 For global commodity prices, the FAO Food Price Index consists of five commodity group price indices, weighted with average export shares of each of the groups for 2002-2004. • Total of 23 commodities (73 prices), in 5 groups: • Cereals • -- wheat (11), maize (1), rice (16) • Oils/Fats • -- soybean, sunflower, rapeseed, groundnut, cottonseed, copra, palm kernel, palm, linseed, castor (1 each) • Dairy • -- whole milk powder, skim milk powder, cheese (2 each), cheese (1) • Meat • -- poultry (13), beef (7), pork (6), sheep (1) • Sugar • -- sugar (1) Source: www.fao.org/worldfoodsituation, 15 Dec 2018

5. Measuring the cost of nutritious diets motivation| methods | data | results | conclusion Existing food price indexes do not measure nutritional value Retail food & food-service prices are weighted by sales volume Retail and wholesale food prices in the United States, 1970-2018 (index values, 1982=100) Retail prices: Food away from home (restaurants etc.) Food at home (groceries) Processed food & feed Unprocessed food and feed Wholesale prices: Source: US. Bureau of Labor Statistics, downloaded 15 Dec 2018. Definitions and updated data are available at https://fred.stlouisfed.org/graph/?g=mr3A

6. Measuring the cost of nutritious diets motivation| methods | data | results | conclusion In poorer countries all food prices are high, compared to earnings and non-food prices Price levels relative to all household expenditure (without adjusting for quality differences) Note: Data shown are local average price levels for each category of household expenditure, smoothed over 159 countries using local polynomial regression to shown the global mean at each level of gross national income (GNI) in purchasing power parity (PPP) terms. Each price level is shown relative to average US prices for that sector in 2011. Source: Preliminary results for Alemu et al. 2019, calculated from World Bank ICP data.

7. Measuring the cost of nutritious diets motivation| methods | data | results | conclusion To measure the cost of nutritious diets, we add to a longstanding literature • For foods in general, a very long history • Fleetwood (1707) food price index = 5 ‘quarters’ of wheat, 4 ‘hogsheads’ of beer • Lowe (1823) different baskets for different socioeconomic groups • Jevons (1865), Laspeyres (1871) weights vary with intake leading to modern CPI • For dietary energy, a long history and wide use • Playfair (1821) chart of wheat prices and wages from 1565 to 1821 • Sukhatme (1961) and FAO’s Prevalence of Undernourishment in calories • Drewnowski (2004) measure of energy cost ($/kcal) and density (kcal/kg) • For nutrient adequacy, more recent history and many specific uses • Stigler (1945) linear programming to compute least-cost diets • USDA Thrifty Food Plan for US nutrition assistance (1975, 1983, 1999, 2006) • SCUK Cost of Diet tool (2009) and FANTA et al. Optifood(2012) for aid programs • For next steps, the CANDASA project is updated least-cost diets, to analyze: • Cost of Nutrient Adequacy (CoNA), comparing to caloric adequacy (CoCA) • Cost of Recommended Diets (CoRD), based on food groups

8. Measuring the cost of nutritious diets motivation| methods | data | results | conclusion To measure the cost of nutritious diets,we must define & measure “nutritious” • Cost of Nutrient Adequacy (CoNA), in USD/day • Least-cost diet with adequate levels of energy + meets 21 nutrient constraints • Include IOM (2011) upper limits and macronutrient ranges for lifelong health • Compare to subsistence cost of energy: Cost of Caloric Adequacy (CoCA) • Cost of a Recommended Diet (CoRD), in USD/day • Least-cost diet within dietary guidelines for each food group • Use locally-defined categories and upper/lower limits • Like CoNA & CoCA, compare to wages, incomes and poverty lines or CPI • Later, may also use nutrition-weighted price indexes (NPI) • Weight prices by nutrient profile scores, instead of expenditure shares as in CPI • Allow comparison of price trends for healthier vs. unhealthy foods

9. Measuring the cost of nutritious diets motivation| methods | data | results | conclusion The Cost of Nutrient Adequacy (CoNA) is based on nutrient-by-nutrient requirements • Essential nutrients required for long-term health CoNA = min. { C = Σipi × qi } least-cost combination of foods With:Σiaie× qi  = Edaily energy balance Σiaij × qi ≥ EARjEARfor >50% of healthy pop. Updated to address dietary transition: Σiaij × qi ≤ ULjbelow UL for excess intake Σiaij × qi ≤ AMDRj,u×E/ej Σiaij × qi ≥ AMDRj,l ×E/ej • CoNA and CoCA are based on international standards • Baseline is woman 19-30, then adjust for age, sex, preg. & lactation • Baseline is 2000 kcal/day, can adjust for physical activity level • Baseline are IOM (2011) values, can replace with other estimates • Baseline is all nutrients are bioavailable, can adjust for phytates etc. • } • within AMDR for macronutrients

10. Measuring the cost of nutritious diets motivation| methods | data | results | conclusion The Cost of a Recommended Diet (CoRD) reflects food-based dietary guidelines • Recommendations are ranges for each food group CoRD = Σipi × qia specific combination of foods Where:qj = n. of servings X serving size for j={1,…, m} food groups and pij = min{pij} with only the least-cost food in each group or pij = median{pij} with only the median food in each group or pij = mean{pij} with all foods equally in each group • National guidelines reflect local politics & culture • Not all countries have adopted or actively use FBDGs • In Africa, only Benin, Kenya, Namibia, Nigeria, Seychelles, Sierra Leone & S. Africa • National FBDGs may reflect country-specific influences • e.g. environmentalism in Brazil, vegetarianism in India

11. Measuring the cost of nutritious diets motivation| methods | data | results | conclusion The Cost of Caloric Adequacy (CoCA) is a benchmark for minimal subsistence • Short-term survival mainly depends on daily energy CoCA = min. { C = Σipi × qi } least-cost combination of foods When: Σiaie× qi  = Edaily energy balance Σiaij × qi ≥ EARjsufficient for >50% of healthy pop. Updated to address dietary transition: Σiaij × qi ≤ ULjbelow UL for excess intake Σiaij × qi ≤ AMDRj,u×E/ej Σiaij × qi ≥ AMDRj,l ×E/ej • Comparison with CoNA reveals added cost of nutrients • } • within AMDR for macronutrients

12. Measuring the cost of nutritious diets motivation| methods | data | results | conclusion A Nutrition-weighted Price Index (NPI) can compare healthy vs unhealthy foods • Nutrition weighted food price index (NPI) • NPI = ∑ipini , where ni is a nutrient score, egNuVaL from 1 (worst) to 100 (best) This weights each expense by its nutritional value • This is comparable to a standard CPI for cost of living • fCPI = ∑ipiwi , where pi and wi are prices and weights in consumer spendingThis weights each price by quantities actually chosen • We might need a hybrid approach, for NCPI to account for how widely purchased is each healthy or unhealthy item • Profile scores aim to guide food choice • We can use scores to measure price changes for more nutritious foods • We can construct separate indexes for different kinds of food

13. Measuring the cost of nutritious diets motivation| methods| data | results | conclusion Food prices may come from different sources • Some countries collect food prices for a market information system • All countries collect food prices for their consumer price index • Sources differ in food lists and data quality • Nutritious foods may be hardest to measure Fruit & vegetable prices depend on weight & quality Photo: Anna Herforth, 2017

14. Measuring the cost of nutritious diets motivation| methods| data | results | conclusion Price data should reflect all candidate foods IANDA (2015-17) helped Ghana MoFA expand price monitoring to more foods Ghana’s MoFA market price reports now includes the additional foods marked in red, for 20 major markets Source: John Nortey, Ghana Ministry of Food and Agriculture (2018)

15. Measuring the cost of nutritious diets motivation| methods| data | results | conclusion Price collection is most systematic for CPI The Malawi NSO targets 51 foods at 29 markets, availably monthly since 2007 Note: items marked with * are omitted from diet cost calculations. Source: Preliminary CANDASA data, from Stevier Kaiyatsa et al. (2019).

16. Measuring the cost of nutritious diets motivation| methods| data | results | conclusion Worldwide prices are collected for the International Comparisons Project (ICP) The ICP has data for 744 foods in 165 countries, for 2011 Source: CANDASA project data, from Alemu et al. (2019)

17. Measuring the cost of nutritious diets motivation| methods| data | results | conclusion Nutrient requirements for an individual aim to avoid multiple burdens of malnutrition Dietary reference intake levels of essential nutrients for healthy adult (median woman aged 19-30, not pregnant or lactating) Chronic disease risk Potential toxicity Note: Data shown are those used for Alemu et al. (2019).

18. Measuring the cost of nutritious diets motivation| methods| data | results | conclusion Nutrient needs vary by age, sex & status We also compare to RDAs, to meet needs of almost all people (97.5%) We use EAR, to meet needs of a median healthy person …and also across individuals, to meet needs of whole households Our base case is an adult woman Calculated from Institute of Medicine (2011), Dietary Reference Intakes. https://www.ncbi.nlm.nih.gov/books/NBK56068 Source: Preliminary CANDASA data, from Yan Bai, Kate Schneider et al. (2019)

19. Measuring the cost of nutritious diets motivation| methods| data | results | conclusion Anti-nutrients and diet alter bioavailability • Phytate that limit zinc absorption can be taken into account using Miller, Krebs and Hambidge (2007) • We have not yet (but will) test for its influence on diet cost in Malawi Impact of phytates and total intake on bioavailability of zinc No phytates High phytates At EAR intake level (8 mg/day) bioavailability is 30% (instead of 50%) Source: Calculated from Miller et al. (2007 Data shown are preliminary CANDASA data, from Yan Bai et al. (2019)

20. Measuring the cost of nutritious diets motivation| methods| data | results | conclusion Nutrients in each food vary by country • Nutrient composition data can differ due to genetics, agronomy and post-harvest handling, but also has a lot of error (contaminants, calibration, etc.) • We test for biological plausibility using log-normality of ratios between local and USDA nutrient content, as gold standard without measurement error • Replacing values outside log-normal range, we obtain regional values: Nutrient densities in pooled Malawi-Tanzania food composition data, relative to USDA standard reference values Dropping extreme values until log-normality cannot be rejected leaves range from 0.36 to 2.75 times USDA reference values Raw data, with a few extreme values Data shown are CANDASA project calculations, from Yan Bai et al. (2019)

21. Measuring the cost of nutritious diets motivation| methods| data | results | conclusion Example results: Cost of Nutrient Adequacy in Malawi by age, sex & maternity status Cost per day to meet all DRI requirements (EAR, UL and AMDR) + adjusting for phytate effect on zinc bioavailability World Bank poverty line ($1.90/person) Note: Data shown are in USD at 2011 PPP prices, for comparison to the World Bank’s $1.90/day poverty line. Source: Preliminary results from Yan et al. (2019).

22. Measuring the cost of nutritious diets motivation| methods| data | results | conclusion Example results for an individual over time Cost of nutrient adequacy by region in Malawi, 2007-2017 (2011 PPP US$/day) Seasonal peaks, year-to-year trends Also, regional variation World Bank poverty line ($1.90/person) Data shown are preliminary CANDASA results, from Kate Schneider et al. (2019)

23. Measuring the cost of nutritious diets motivation| methods| data | results | conclusion The mix of foods varies, driven by constraints Share of dietary energy from each food in least-cost diets for Malawi, 2007-2017 Woman, 19-30 EAR only Cost/day: US$1.06 ± 0.38 Woman, 19-30 EAR+UL+AMDR Cost/day: US$1.17 ± 0.39 For macronutrient balance, less starchy staples, more legumes & fats Data shown are preliminary CANDASA results, from Yan Bai et al. (2019)

24. Measuring the cost of nutritious diets motivation| methods| data | results | conclusion For Ethiopia, we can compare to wages Cost of nutrient adequacy (CoNA), caloric adequacy (CoCA), And real wages in Ethiopia, 2001-2017 (2011 PPP US$/day) Great success in wage growth No rise in CoNA since 2011 Big reduction in CoCA since 2008 Data shown are preliminary CANDASA results, from Fantu Bachewe et al. (2019)

25. Measuring the cost of nutritious diets motivation| methods| data | results | conclusion Ethiopia’s green revolution may now turn towards reducing cost of nutrients Cost of nutrient adequacy premium over caloric adequacy, in absolute (CoNA-CoCA) and ratio terms (CoNA/CoCA) Will the nutrient premium keep falling, or rise again? Data shown are preliminary CANDASA results, from Fantu Bachewe et al. (2019)

26. Measuring the cost of nutritious diets motivation| methods| data | results | conclusion Seasonal variation in diet costs is greater for nutrient-dense foods • Monthly variation in cost of nutrient adequacy vs daily energy in Tanzania, 2011-15 CoNA CoCA 2011 US dollars per day Cost of nutrients has more seasonality than cost of calories, perhaps due to perishability and transport Note: Data shown are coefficient and 95% confidence interval on calendar month indicators, relative to May. Orange bars for cost of calorie adequacy (CoCA) not significantly different from zero. Data shown are preliminary CANDASA results, from Yan Bai et al. (2018)

27. Measuring the cost of nutritious diets motivation| methods| data | results | conclusion Seasonal variation in diet costs is greater for nutrient-dense foods • Harmonic regression results for cost of nutrient adequacy in Tanzania, 2011-15 Harmonic regression reveals the amplitude and timing of fluctuations CoNA CoCA 2011 US cents per day Cost of nutrients has more seasonality than cost of calories, perhaps due to perishability and transport Data shown are preliminary CANDASA results, from Yan Bai et al. (2018)

28. Measuring the cost of nutritious diets motivation| methods| data | results | conclusion Compared to a subsistence diet, nutritious diets are more costly in poorer countries (and some rich ones) Cost of nutrient adequacy (CoNA), relative to caloric adequacy (CoCA, with only starchy staples) CoNA / CoCA Data shown are preliminary CANDASA results, from Alemu et al. (2019)

29. Measuring the cost of nutritious diets motivation| methods| data | results | conclusion Relative to other foods, the cost of nutritious diets is prohibitively high for many poor people Nutritious diets (CoNA) cost >50% of the $1.90 poverty line andtwice as expensive as least-cost energy diet (CoCA) Darker: CoNA (Cost of Nutrient Adequacy) Lighter: CoCA (Cost of Caloric Adequacy) $1.90/day $0.85/day Data shown are preliminary CANDASA results, from Alemu et al. (2019)

30. Measuring the cost of nutritious diets motivation| methods| data | results | conclusion In poor countries, the cost of a nutritious diets often exceeds current average per-capita spending on food Nutritious diets (CoNA) as a fraction of actual food expenditure per capita, from national accounts (2011) Mean per-capita expenditure 50% of per-capita expenditure

31. Measuring the cost of nutritious diets motivation| methods| data | results | conclusion Which requirements most influence diet cost? Semi-elasticity of CoNA to nutrient constraints (US$/pct change) Calcium is the most expensive requirement, especially in poor countries Energy requirements are still a big contributor to diet cost Folate requirements are more easily met in rich countries Data shown are preliminary CANDASA results, from Alemu et al. (2019)

32. Measuring the cost of nutritious diets motivation| methods| data | results | conclusion For food-based dietary guidelines, we use the Cost of a Recommended Diet (CoRD) In Africa, the only countries with dietary guidelines are Benin, Sierra Leone, Nigeria, Namibia, and South Africa (+Kenya soon) Ghana prices not available for dairy Cost per serving for lowest-cost item in each food group (Ghana, 2015) Guidelines specify the number of servings in each group Cost/serving (PPP US$/item) Data shown are preliminary CANDASA results, from Anna Herforth et al. (2018)

33. Measuring the cost of nutritious diets motivation| methods| data | results | conclusion The Cost of a Recommended Diet (CoRD) depends on which foods are used With the median item in each food group (except dairy), total cost would be US$1.37/day Ghana price data include several high-cost vegetables and protein foods, so those groups can be very expensive Cost per day for a recommended diet, median of all items (Ghana, 2015) Cost per day (2011 US$ in PPP terms) Data shown are preliminary CANDASA results, from Anna Herforth et al. (2018)

34. Measuring the cost of nutritious diets motivation| methods| data | results | conclusion The Cost of a Recommended Diet (CoRD) depends on price and quantity per day With the lowest-cost items in each food group (except dairy), total cost would be US$0.75/day Cost per day for a recommended diet, lowest-cost items only (Ghana, 2015) Cost per day (2011 US$ in PPP terms) Data shown are preliminary CANDASA results, from Anna Herforth et al. (2018)

35. Measuring the cost of nutritious diets motivation | methods | data | results | conclusion Conclusions and next steps • CANDASA is developing and use economic price indexes that reflect nutritionists’ definitions of a healthy diet • A balance of essential nutrients, using DRIs to calculate CoNA • Dietary guidelines, using food groups to calculate CoRD • Nutrient profile scores for healthy/unhealthy foods, to calculate NPI • For research, the gold standard remains nutrient adequacy • Initial applications include: • Seasonality in the added cost of nutrient adequacy over daily energy • International differences associated with national income and urbanization • Policy-induced changes in average levels and also disparities in diet cost • For policy and programs, simpler measures are useful too • Ghana Statistical Service (GSS) and Min of Food & Ag (MoFA) officials intend to add NPI and CoRD to their monthly reports

36. Measuring the cost of nutritious diets motivation | methods | data | results | conclusion Thank you! Special thanks to all price enumerators The CANDASA project is funded by UKAid and the Bill & Melinda Gates Foundation (OPP1182628). Software tools will be published on the Gates Open Research platform, and also available on the project website at http://sites.tufts.edu/candasa Photo: Anna Herforth, 2017