Heterogeneity in Nutrient Costs: Impact on Health in Malawi

1. Heterogeneity in the cost of nutrient adequacy by age, sex, pregnancy and lactation statusin Malawi Yan Bai and William A. Masters Friedman School of Nutrition Science & Policy Tufts University AAEA 2019 -- track session on market prices and malnutrition in developing countries 23 July 2019

2. INTRODUCTION CONCLUSIONS AND NEXT STEPS METHODOLOGY AND DATA RESULTS Outline • Introduction • Methodology and Data • Results • Conclusions Photo: StevierKaiyatsa

3. INTRODUCTION CONCLUSIONS AND NEXT STEPS METHODOLOGY AND DATA RESULTS Introduction • Access and affordability of all foods needed for a healthy diet is necessary (but not sufficient) for improved nutrition and health • High or volatile food prices limit access and may cause under-nutrition (Brinkman et al., 2010; Bouis, Eozenou and Rahman, 2011; Green et al., 2013; Hirvonen et al., 2015) • Differences among food groups may worsen diet quality and contribute to obesity and metabolic diseases (USDA ERS; Dangour et al., 2013; Duffey et al., 2010) • Existing market price indexes cannot measure access to all needed nutrients • World and national food price indexes use commodity prices, not retail foods • Consumer price indexes measure current cost of living, not cost of improved diets • Nutrition researchers specify particular foods or diets, not allowing substitutions • We use prices of all foods, combined with their nutrient composition and individual requirements, to compute least-cost diets at each place & time

4. INTRODUCTION CONCLUSIONS AND NEXT STEPS METHODOLOGY AND DATA RESULTS Introduction World food prices (traded commodities only) National food prices (share of total expenditure) • Existing price indexes aim measure the cost of what is bought and sold • World food markets for commodities • Producer prices for farm income • Consumer price index for cost of living • Nutrition researchers measure the cost of pre-defined foods or food groups • Specific quantities of each one, for all people • No substitution between foods or food groups • Least-cost diets allow substitution, but specify needs of an individual person • This study focuses on variation in needs across individuals, and heterogeneity in the cost of a nutritious diet The US MyPlate vs The EAT Lancet Diet

5. INTRODUCTION CONCLUSIONS AND NEXT STEPS METHODOLOGY AND DATA RESULTS Introduction • The CANDASA project develops & applies new price indexes for Changing Access to Nutritious Diets in Africa and South Asia • We focus on variation in costs across Malawi, with 18 million people, 84% rural with two-thirds under $1.90/day • Chronic malnutrition (stunting, anemia) especially among women and children • Would the nutrients needed for healthier diets be available, at affordable prices? • The Cost of Nutrient Adequacy (CoNA), defined as the least expensive way to meet all nutrient requirements, provides a lower bound on cost of a nutritious diet (Masters et al., 2018) • If sufficient nutrients are not now available at affordable prices, safety nets and transfers as well as food system change would be needed for improved diets

6. INTRODUCTION CONCLUSIONS AND NEXT STEPS METHODOLOGY AND DATA RESULTS Methodology and data • Least cost diets have a long history in economics and nutrition • Proposed by Stigler (1945) for military rations, subsequently used for nutrition assistance programs in the U.S. as the Thrifty Food Plan, low-income countries as Optifood or the World Food Program’s cost of diet tool • We use the Cost of Nutrient Adequacy (CoNA) as a price index to measure differences over time and space • CoNA: min. Ck = Σipiqi subject to relevant DRI requirements • Price data are monthly from 2007-2017, for 55 items in all major food groups, at 17 market locations around Malawi • The aim of this paper is to quantify variation in nutrient requirements, and affordability of nutrients for the poor at each age, sex and pregnancy or lactation status

7. INTRODUCTION CONCLUSIONS AND NEXT STEPS METHODOLOGY AND DATA RESULTS Methodology and data • The DRIs specify min. & max. levels for up to 20 nutrients (34 constraints) Source: Dietary Reference Intakes (DRI) values for the US & Canada, last revised 2011. Available online at https://www.nal.usda.gov/fnic/dietary-reference-intakes

8. INTRODUCTION CONCLUSIONS AND NEXT STEPS METHODOLOGY AND DATA RESULTS Methodology and data • Nutrient requirements vary by food contexts and individual status • Estimated Average Requirements (EARs) meet needs for 50% of a healthy population • Recommended Dietary Allowances (RDAs) and Adequate Intake (AI): meet needs for 97.5% of a healthy population • Acceptable Macronutrient Distribution Ranges (AMDRs): limit chronic disease risk • Antinutrients may limit bioavailability Zinc absorption depends on total dietary zinc & phytates Source: Miller, Krebs and Hambidge, 2007 • WHO and FAO provide DRIs (RDA equivalent) of zinc and iron for all gender-age groups assuming lower bioavailability • Low-bioavailability diet assumption? • Relationship between phytate in diets and zinc bioavailability (the Miller Equation) • Food or diet?

9. INTRODUCTION CONCLUSIONS AND NEXT STEPS METHODOLOGY AND DATA RESULTS Methodology and data • Five nutrition cases being considered: • EARs only – meet needs of half population, for population level assessment; • EAR plus upper limits (UL) and Acceptable Macronutrient Distribution Range (AMDR) • UL constrain micro-nutrients to be under toxicity level • AMDR constrain macro-nutrients to be in “acceptable ranges” (long-term health) • Using RDA/AI to replace EAR: meet needs for 97.5% of healthy population • Using WHO/FAO DRIs for zinc and iron to account for low bioavailability • Zinc: 1.2x-2.8x of RDAs for Phytate Zinc molar ratio of total diet > 15 • Iron: 1.5x-4.1x of RDAs for only ~15% of absorption rate • Using Miller equation predicting zinc absorption of foods • 22 gender-age groups and 5 nutrition cases = 100 scenarios

10. INTRODUCTION CONCLUSIONS AND NEXT STEPS METHODOLOGY AND DATA RESULTS Energy share by foods/food groups 1 2 3 4 5 • Example shows the average energy share for a healthy male 19-30 y/o • Share of the diet from starchy staples declines as nutrient needs rise • Diet quality is most affected by AMDR and UL constraints, rather than AER vs RDA difference • Pulses, nuts and seeds, animal foods, nutr-dense F&V, and even oils and fats are playing increasingly important role in CoNA food selections

11. INTRODUCTION CONCLUSIONS AND NEXT STEPS METHODOLOGY AND DATA RESULTS Cost per day varies widely by individual needs 1 2 3 4 5 $1.9 $1.5 • In four of the five nutrition cases, the lactating women groups in average are facing the highest Cost of Nutrient Adequacy (CoNA) in Malawi with a range about 2-3 USD (2011PPP) per day • However, if considering low-availability of zinc and iron (WHO standards), CoNA of adult women bncrease significantly (4-6 USD per day)

12. INTRODUCTION CONCLUSIONS AND NEXT STEPS METHODOLOGY AND DATA RESULTS Cost per calorie of food also varies widely 1 2 3 4 5 • Diet quality, defined as cost per calorie of meeting all nutrient needs, is more costly for women in almost all age groups and all nutrition cases; older adults also require a higher-cost diet per calorie; • With low bioavailability of zinc and iron (WHO case), adult women require the highest-cost diets to avoid anemia and other consequences of mineral deficiencies

13. INTRODUCTION CONCLUSIONS AND NEXT STEPS METHODOLOGY AND DATA RESULTS Conclusions • Substitution between foods and food groups plays an important role in meeting nutrient requirements at low cost • Even at lowest possible cost, required nutrients are unaffordable for many Malawians • There are large differences in cost per day and cost per calorie by age, sex and pregnancy/lactation status • Daily cost is especially high for lactating and pregnant women • Cost per calorie is especially high for women of reproductive age, especially for diets with low bioavailability of iron and zinc • Safety net transfers, as well as food system changes to lower food costs, would be needed for women to meet their nutrient needs • Further studies are needed to address overall household costs (Schneider et al. 2019), as well as spatial and seasonal variation in unaffordability (Bai et al. 2019), before estimating the number of people for whom required nutrients are not affordable

14. INTRODUCTION CONCLUSIONS AND NEXT STEPS METHODOLOGY AND DATA RESULTS Next steps • CoNA has great potential to measure even more complicated nutritional goals • Feature amino-acid requirements into the model: does the current method capture the importance of high-quality protein or the animal sourced foods? • For more specific demographic groups, such as children under 3 years old, further investigation may make more specific science-based nutritional/food requirements. The current method may underestimate their costs; • For over-nutrition concerns, may add more specific constraints for certain nutrients, such as fiber, omega3 and omega6 fatty acids, sodium, saturated fat and trans-fat etc.; • How do actual food choices relate to the least-cost sources of nutrients? As food prices fall and incomes rise, do traditional and existing culinary practices and food preferences lead the poor to consume required nutrients?